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18/04/2013

How to wire Four Speakers to One Amplifier

In an earlier article we looked at the issues involved in connecting multiple speakers to one amplifier. In this article we look at some of the practical ways of wiring four speakers to each amplifier (left and right) . For example, it is normal to have your main HiFi amplifier in the lounge room. It is also common to want to have some speakers in the family room, outside (patio or pool area) and in the workshop or garage.

So let’s look at the various ways of wiring at least 4 pairs of speakers to one HiFi amplifier. If you need to connect just 2 pair of speakers to a HiFi stereo amplifier (that is, 2 speakers to 1 amp), see my article on How to connect 2 speakers to 1 amplifier.

I have had many people over the years tell me it is easy to connect multiple speakers – all you have to do is wire the speakers in series. When I’ve grilled them about how they did that, they say they simply wired them as a “daisy chain”, one after the other. When questioned further, I find they have actually wired them in parallel, and have wondered why the amplifier doesn’t like it.

In the following diagrams I will only show the wiring for one side of a stereo amplifier, let’s say the left side of the stereo. In reality this wiring needs to be duplicated for the right side speakers too.

Four speakers wired in parallel

This diagram shows how to wire four speakers in parallel.

Some people call this “daisy chain” as it connects one speaker after another, but it is really wiring them in parallel.

It is the same as wiring each speaker directly from the amplifier, like this:

Wiring speakers in parallel is not a good way of connecting three, four or more HiFi speakers as it puts too much load on the amplifier (as explained in earlier article)

Four speakers wired in series

This diagram shows how to wire four speakers in series.

Again this is not a recommended way of wiring four speakers (although it will work), nor is it very practical. Apart from the hassle of having to wire from one speaker to the next, if one wire is disconnected, then all speakers will stop working. Also each speaker affects the total load seen by the amplifier which will only allow it to work up to one eighth of its potential. This is closer to a daisy chain as each speaker and corresponding single wire forms part of a daisy chain loop.

Four speakers wired in Series-Parallel

This diagram shows how to wire four speakers in series-parallel.

This is a safe way of wiring four speakers (without a switch box or separate volume controls). It is a combination of series and parallel. Providing all the speakers are 8 ohms, this will work as the total impedance is also 8 ohms,

While this will technically work, it is often not practical as you need lots of wires interconnecting all the speakers and there is no control over any one speaker – they all are controlled by the amplifier volume control at the same time. This is not good if you only want music in one area of the house, and not everywhere at the same time – apparently neighbours don’t always like listening to the same music as you (through the outside speakers).

Speaker Selector Switch

The easiest and a safe way to connect 4 pairs of HiFi speakers is to use a 4 zone speaker selector switch.

This is relatively simple to wire, just run a wire from the central location (lounge room) to each speaker. The box should also look after any impedance matching to prevent amplifier overload. Although the volume will be similar in all areas, at least it is possible to turn off the speakers in the areas you don’t want sound. It is normal to locate the selector switch adjacent to the amplifier. Remember to connect the lounge room speakers to one switch so they can be turned off when you only want music outside.

Please note, speaker selector switches are designed for multi-room installs in a home. They are generally suited for low power (under 100 watts) amplifiers. They should be not be considered in a commercial install or for use with high output power amplifiers.

Speaker selector switches can use various techniques to allow multiple speakers to be connected to the one amplifier, namely:

a series resistor (around 2½ – 5 ohms) to restrict the minimum impedance of the speakers circuit to this value. This simple series resistor if often marketed as “manual impedance protection”. They are normally good for lower powered speakers, and the resistor can get hot at high volume levels. If this switch is not selected, you have no protection when running all the speakers together.
combining the different speakers in series and/or parallel to keep the overall impedance above 4 ohms. This is similar to the series-parallel wiring above, but it all happens in the box for you.
matching impedance transformers – this is the best, but it is also the most expensive.

All these methods allow multiple speakers, but at a lower volume than using just one speaker. This is logical as the signal is being shared by more than just the one speaker. To see how the power is distributed by the different types of speaker selector switches, see my Speaker Selector Switch Simulator.

If you are interested in using a speaker selector switch, check out my summary article on speaker selector switches – it discusses the features and uses in more detail, and summarises all the units bought from Amazon through this web site. You can also download the user’s manual for most models – before you buy it.

Click here to browse 4 way speaker selector switches available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

There are also available speaker selector switches which can be controlled through your smartphone or Alexa. Geoff has written a review of the Audioflow series of switches which you can read here.

Speaker Selector with Volume Controls

A more practical (and a little bit more expensive) way it to substitute the selector switch with a unit that also has volume controls. This allows the volume in each zone (area with a pair of speakers) to be controlled at the central location.

Some volume control units also have impedance matching. This means they have a switch (normally on the back panel – but sometimes inside) which allows you to tell it you are connecting 2, 4 or 8 pairs of speakers to the one amplifier. Once this switch is set, you don’t need to worry about overloading the amplifier. Some units don’t have a switch but are set for four speakers. Impedance matching works by appearing to the amplifier as just one speaker, while it evenly splits the signal to all four speakers – in reality, each speaker only gets 1/4 of the sound that comes from the amplifier (assuming you selected x4 on the switch).

Other volume control units (read cheaper) don’t have impedance matching. These units rely on you probably not needing to run all four sets of speakers flat out at the same time. While this is not as safety assured as using impedance matching, it may suit some installations. If you only want low level music in the workshop and family room, then this will be fine. If you are having a party and want loud music outside, just make sure the workshop and lounge room are turned down – this reduces the total load and this effectively means only one or two pairs of speakers are connected to the amplifier.

Remember to allow a volume control for the lounge room speakers so they can be controlled also.

Click here to browse 4 way speaker selector switches with volume controls available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

In-Wall Volume Controls

Sometimes it is not convenient to have to go to the lounge room to control the volume of the speakers – especially if you are some distance away and the phone starts to ring. Therefore it can be useful to have a volume control in each zone (area) where there are speakers. This way, the volume for the speakers for the workshop is controlled in the workshop. The disadvantage of this is if you leave the volume control up (say for the outside speakers) and the next morning you play music without going outside – you will be entertaining the neighbours with your music in the morning as well as the night before.

In-wall volume controls are similar to the volume controls mentioned above – they come with impedance matching or without impedance matching. For more than one pair of speakers you would normally want impedance matching. If you are having two zones (two pairs of speakers or four speakers) then you will select the x2 on the back of the impedance matching volume control. Similarly, if you are using 3 or 4 pairs of speakers, you will select x4.

Bear in mind that these are mostly “in-wall” controls. If you need to mount them on a solid brick or concrete wall, you will need a big mounting block, or a deep recess in the wall. The transformers on these volume controls are normally deeper than a standard mounting block for solid walls. The greater the power handling ability of the volume controls, the larger the recess required (and the more expensive the control).

Wiring these volume controls is fairly simple. Run a speaker cable (probably two, one for left side and one right side) from the amplifier to the volume control. Then run a speaker cable from the volume control to each speaker.

Remember to allow a volume control for the lounge room speakers so they can be controlled also.

You can use this method for 2 speakers, 4 speakers or more.

Click here to browse wall volume controls available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

Practical Considerations in Wiring Four Speakers

The above installations will work, but they have some limitations. The biggest limitation is the volume control on the amplifier. This controls the maximum volume to all four speakers. The individual volume controls for each speaker only reduce the level coming from the amplifier – they can’t make the sound louder than what the amplifier produces. This means the amplifier volume control needs to be set at the level of maximum volume you want for any given speaker. However it is not wise to set it at full volume. You don’t want the amplifier running flat out but all the speakers turned way down (this is like revving the car engine at maximum and then only letting the clutch out a little bit) – far better to run the amplifier only to the maximum required.

The best method for setting up a system with speaker volume controls is:

turn all the speaker volume controls all the way up
gradually increase the volume control of the amplifier until the music is just louder that you would normally want it.
This is the position for the amplifier volume control.
you can now turn each speaker down a few steps to the level you want.

The above method will work fine until someone uses the remote control and changes the volume. This will happen regularly if you watch movies or TV and listen to the sound through your HiFi amplifier/speakers. One solution is to hide the remote control – but this isn’t always convenient. There is a better solution, but you may not need it.

The installations above with the speaker selector switch, or with the volume controls suit a number of situations. They are very suitable when you want the same music (from an MP3 player or media centre) available throughout the house and you don’t touch the amplifier. I have installed many of these systems in houses where the amplifier is only turned on in the morning and turned off at night. Sometimes the amplifier is installed in a ventilated cupboard so it is never seen nor touched. This allows the household to move around the house listening the same music in every room.

However if your amplifier is used while watching TV or movies and the volume is constantly being adjusted with the remote control, then the other speakers in house will also be adjusted accordingly. The easiest way to solve this problem is with a second amplifier. This is my preferred method. Connect the line out of the main amplifier into the “slave” amplifier. This way, the program is the same in every room, but the HiFi amplifier volume can be changed as much as you like, without affecting the other speakers. The volume on the slave amplifier can be set (as outlined above) and then never touched.

The slave amplifier can be a second hand amplifier, an old “stereo”, or a new stereo amplifier. Some HiFi (main) amplifiers have a power socket at the back to allow other equipment to be connected. If this is the case, then plug the slave amplifier in to this power socket and it will be turned on and off with the main amplifier.

In Closing…

I hope this has helped you understand how-to, and how-not-to, wire four (or more) pairs of HiFi speakers around your house. The video in the article Understanding Speaker Impedance explains how each of the different types of Speaker Selector Switches provides impedance protection or impedance matching. Also my Speaker Selector Switch Simulator provides an interactive way to see how they treat impedance and power sharing.

For a practical discussion on how to wire just 2 speakers to an amplifier (4 speakers to a stereo amp), see my article on How to connect 2 speakers to 1 amplifier.

If you need to wire more than four speakers, particularly in a commercial installation, see the article on Distributed Speaker Systems.

Keep in mind that changing the total load impedance of an amplifier will increase or decrease the power output of the amplifier. See Multiple Speakers Change Amplifier Power for more details. Also different speakers may sound louder or softer than others due to there sensitivity – see Understanding Speaker Sensitivity for a better understanding.

Also if the speakers each have a different impedance, then there will be different power levels available to each speaker. For more detail see How Multiple Speakers Share Power.

Many practical examples of the methods outlined above have been explored in the comments below.

How do I Connect Multiple Speakers to my HiFi Amplifier

Home Speakers

Geoff

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31/03/2012

285

How do I Connect Multiple Speakers to my HiFi Amplifier

I am often asked “How do I connect multiple speakers to my amplifier?” Before I answer, let’s define what we mean by the word “amplifier”. In a stereo “amp” there are two amplifiers – one for the left, and one for the right channel. That is, in the one amplifier box, there are two different amplifiers. In a home theatre amplifier with surround sound, there may be 5, 6, 9 or 11 amplifiers in the one “amplifier” box. For the purposes of this article, we are talking about connecting multiple speakers to a single amplifier only, that is, either the left or the right, or any single amplifier. Of course you can connect multiple speakers to both the left and right amp of a stereo – you just need to follow the principles twice, once for each amp.

Multiple Speakers on One Amplifier

Multiple speakers - Connecting two speakers

By adding an extra speaker to the output of an amplifier, you are adding to the load of the amplifier. That is, two speakers is double the load of one speaker. Most amplifiers can cope with a load of two speakers. Similar to a passenger on a small motor bike: add another passenger and the load the bike needs to carry is doubled, but most bikes will cope with two passengers.However adding more than two speakers will normally overload the amplifier. Similar to the motor bike example: it can cope with two passengers, but starts to struggle with 3 or more passengers. Most modern amplifiers have some sort of limiting circuit to stop the amplifier working if it is overloaded. In some amplifiers, this involves blowing a fuse inside the amplifier. In other (more technical) amplifiers they will automatically turn off until you turn it back on with a load that is under its maximum safe load.Amplifiers may cope with multiple speakers at low volumes,

multiple speakers - bike example (400 x 267)

but will have issues when running at high volume levels. Similar to the motor bike illustration: it may cope with 3 or 4 passengers while going slowly on a flat road, but it will struggle when asked to work harder (like go up a hill or go faster). To be safe, never overload your amplifier.To understand the technical reason for this, I strongly encourage you to read through the technical explanation below. A good overview on this can be found in the video in the article on Understanding Speaker ImpedanceIf you just want to know how to wire two speakers to one amp, (4 speakers to a stereo) without switching or individual volume control, see the article on How to connect 2 speakers to 1 amplifier.If you want speaker on/off or individual volume control, or you want more than two pair of speakers, (like three, four or more pairs) connected to your HiFi amplifier, see the article How to wire four speakers to one amplifier.If you need to wire more than four pairs of speakers, particularly in a commercial installation, see the article on Distributed Speaker Systems.

Technical Explanation

In the specifications for a hifi amplifier might say Output: 100 watts @ 4 ohms

This is normally specifying the maximum power output of the amplifier and the minimum resistance in the speaker circuit. So in this case, the amplifier will produce 100 watts of power when run at full volume connected to a speaker load of 4 ohms. The ohms bit is our main concern. Ohms is a measurement of resistance. In the case of speakers, it is the measurement of how much resistance the speaker has in the circuit connected to the amplifier. Technically speaking, the resistance of speakers is called “impedance”, as the output of an amplifier is AC, and resistance in an AC circuit is called impedance.To understand what all this means, we need to get technical and use some formulas. An explanation of these formulas can be found in the article The Dreaded Ohms Law.

We will use the summary table from that article. You don’t need to understand these formulas but we need to use them.In our example, we know:Power is 100 watts: P = 100Impedance is 4 ohms: R = 4So we can use the various formulas to calculate the output voltage(V) and current(I) of the amplifier.Calculation of output voltage(V): $V=\sqrt{P\times R}=\sqrt{100\times 4}=\sqrt{400}= 20\ volts$ Calculation of output current (I): $I=\sqrt{\frac{P}{R}} =\sqrt{\frac{100}{4}} =\sqrt{25} =5\ amps$ So, from the specifications and a couple of calculations, we now know the following:Power=100 watts Impedance (resistance) = 4 ohms Voltage = 20 volts Current = 5 ampsAn equivalent circuit will help us visualise what is happening.

multiple speakers - connecting 1 4 ohm speaker

This illustrates the maximum capacities of the amplifier. With a load impedance (speaker) of 4 ohms, the amplifier needs to deliver 5 amps to produce the 100 watts of power. This amplifier will normally have some sort of limiting circuitry to limit the current output to no more than 5 amps. The reason being, all the electronics will be designed to deliver 5 amps. Therefore to avoid “blowing up” the output stage (and possibly the power supply), some form of current limiting is employed. The most simplest form of a current limiting circuit is a fuse. If a 5 amp fuse is placed in series with the output, then it would supply the current until the total current exceeds the 5 amps at which point it would “blow”.Remember, these are the maximum ratings of the amplifier. In practice, many speakers are made to have an impedance of 8 ohms. Therefore the equivalent circuit would be similar, but with a different impedance, therefore a different current as shown here: $I=\frac{V}{R} =\frac{20}{8} =2.5\ amps$

multiple speakers - connecting one 8 ohms speaker

The power output of the amplifier is also reduced: $P=\frac{V^2}{R}=\frac{20^2}{8}=\frac{400}{8}=50\ watts$ In practice, because the speaker impedance is increased, the load is decreased and the amplifier is capable of outputting around 23 volts which gives a maximum power output of 70 watt @ 8 ohms.The important principal is: the higher the speaker impedance, the less current required from the amplifier. Also, the lower the speaker impedance, the more current required from the amplifier.OK, this is all very good, but what about connecting two or more speakers to the amplifier? Glad you ask, this is the fun bit. Let’s connect two 8 ohm speakers to the one amplifier.

multiple speakers - connecting 2 8 ohms speaker in parallel

You will notice that each speaker still draws 2.5 amps from the amplifier. So the combined load on the amplifier is now drawing a total of 5 amps (2 x 2.5=5). You may have noticed that this is the same current (and therefore the same total load) as one 4 ohm speaker. That’s right, two 8 ohm speakers in parallel is the same as one 4 ohm speaker. If you like, you can prove this using the formula for calculating resistances in parallel. If you’ve had enough formulas, just skip this and go to the next paragraph.

$\frac{1}{R_{Total}}= \frac{1}{R_1}+\frac{1}{R_2}\ \ so\ \(\frac{1}{R_{Total}}= \frac{1}{8}+\frac{1}{8}=\frac{1}{4}\ \ therefore\ {R_{total}=4\ ohms$

The good news is, this is within the specifications of the amplifier as we saw earlier. So, as long as the speakers both have an impedance of 8 ohms (or more), and the amplifier is rated for 4 ohms, then you can safely run the amplifier with two speakers.

Now what do think is going to happen if we are having a party in several rooms and need multiple speakers (like four speakers) connected to one amplifier on the stereo? The circuit would look like this:

multiple speakers - connecting four 8 ohm speakers

If the poor old amplifier can still hold the 20 volts, each speaker is still trying to draw 2.5 amps, meaning the total current draw from the amplifier is 10 amps – way above its specified capabilities. At this point, we hope it has a limit/protection circuit and has turned itself off, or at the very least the 5 amp protection fuse inside has blown. If there is no current limiting circuitry, then quickly turn the power off when you see the smoke rising from the amplifier.

For those who like the mathematical evidence rather than just the pictorial reasoning, the calculation of the total resistance looks like this:

$\frac{1}{R_{Total}}= \frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}+\frac{1}{R_4}\ \ so\ \ \(\frac{1}{R_{Total}}= \frac{1}{8}+\frac{1}{8}+\frac{1}{8}+\frac{1}{8}=\frac{1}{2}$

$therefore\ {R_{total}=2\ ohms$

and then calculate the current:

$I=\frac{V}{R} =\frac{20}{2} =10\ amps = smoke.$

For an easy way to calculate the total impedance of speakers in parallel, try my simple Speakers in Parallel Calculator.

Keep in mind that changing the total load impedance of an amplifier will also increase or decrease the power output of the amplifier. See Multiple Speakers Change Amplifier Power for more details.Also if the speakers each have a different impedance, then there will be different power levels available to each speaker. For more detail see How Multiple Speakers Share Power.

Multiple Speaker Selector Switches

There are ways of connecting multiple speakers to a HiFi amplifier without causing damage, but not by simply connecting one speaker onto the other. For a detailed and practical outline of how to connect four or more pairs of speakers to a HiFi amplifier, see this article. The simple method (with the limitations listed in the other article) is to use a speaker selector switch. A 4 zone switch will allow up to 4 pairs of speakers to be connected to the one amplifier.

Please note, speaker selector switches are designed for multi-room installs in a home or small low power installs (like an office or cafe). They are generally suited for low power (under 100 watts) amplifiers. They should be not be considered in a commercial install or for use with high output power amplifiers.Speaker selector switches can use various techniques to allow multiple speakers to be connected to the one amplifier, namely:

a series resistor (around 2½-5 ohms) to restrict the minimum impedance of the speakers circuit to this value. This simple series resistor is often marketed as “manual impedance protection” or simply “Protection”. They are normally good for lower powered amplifiers, and the resistor can get hot at high volume levels.
combining the different speakers in series and/or parallel to keep the overall impedance above 4 ohms.
matching impedance transformers – this is normally the best, but it is also the most expensive.

Click here to browse Speaker selector switches available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

All these methods allow multiple speakers, but at a lower volume than using just one speaker. This is logical as the signal is being shared by more than just the one speaker. To see how the power is distributed by the different types of speaker selector switches, see my Speaker Selector Switch Simulator.For a more detailed explanation and summary of the features of speaker selectors, see my Speaker Selector Switch Summary.There are also available speaker selector switches which can be controlled through your smartphone or Alexa. Geoff has written a review of the Audioflow series of switches which you can read here.Instead of using a speaker selector switch to connect multiple speakers to your hifi amplifier you can use impedance matching volume controls, as outlined in the article on connecting four speakers.

Conclusion

Depending on the impedance of your speakers and the rating of your amplifier, you should be able to use two pairs of speakers connected to a HiFi amplifier. However, it is wise to use the example given above as a guide and use the figures in the specifications of your amplifier and speakers to calculate and know for sure what the outcome will be. Otherwise use a multiple speaker selector switch and/or impedance matching volume controls. The video in Understanding Speaker Impedance explains how speaker selectors help with impedance protection

For a practical discussion on how to simply wire just 2 pair of speakers to a stereo amplifier (4 speakers to a stereo amp), see my article on How to connect 2 speakers to 1 amplifier.

For more practical information of how to wire two, three, four or more speakers to one amplifier using speaker selector switches and volume controls, see this article.

Many practical examples of connecting multiple speakers to your HiFi have been discussed in the comments below. If, after reading these discussions, you still have a question please read the FAQs before submitting your question.

Thanks to James from Sydney, Australia who suggested this topic.

How to Connect 2 Speakers to 1 Amplifier

Home Speakers

Geoff

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06/07/2015

195

How to Connect 2 Speakers to 1 Amplifier

In this article we look at how and when to connect 2 speakers in parallel or series. Both the theory and practical points on how to connect 2 speakers are discussed. Connecting 2 speakers in parallel or series to your amplifier is useful when:

you don’t need to turn each speaker on or off individually, or
you don’t need to have separate volume controls for each speaker.

If you need to turn each speaker on or off individually or have separate volume controls, you may need a speaker selector switch. In this case you should read the articles on connecting multiple speakers, wiring 4 speakers, and/or my summary of speaker selector switches.

Many people get confused when we talk about a stereo amplifier. A stereo amp simply has two amplifiers built into the one box. We are not talking about connecting two speakers to a stereo amp, as that simply involves connecting one speaker to each amplifier (left and right). There are many cases when you want to connect four speakers to a stereo amp, that is, to connect 2 speakers to each amplifier – or four speakers in total. For the rest of this article, when we talk about an amplifier, we are talking about either the left or right amplifier only.

You may want to connect 2 speakers to one amplifier without individual switching or volume controls if you:

have a large living area with four ceiling speakers, or
want to cover a large backyard with four speakers, or
have any situation where two speakers are not enough.

The are two basic ways of connecting two speakers together – either in series or parallel.

Should 2 speakers be connected in Series or Parallel?

Whether 2 speakers connected to one amplifier should be in series or parallel mostly depends on the impedance of the speakers.

The impedance of the speakers should be written on the back of the speaker or speaker box. The impedance of a speaker is normally 4 ohms, 6 ohms or 8 ohms. If it isn’t written on the back of the speaker, check any paper work that might have come with the speaker, or look up the specifications on the web. The Ω symbol is often used instead of writing “ohms”.

If both speakers are 8 ohms or more, then the speakers can normally be wired in parallel.

If the speakers are less than 8 ohms, then to be safe, you should wire them in series.

Connect 2 Speakers in Parallel

To calculate the total load impedance of speakers in parallel, see my Speakers in Parallel Calculator.

If both speakers are 8 ohms or more, then it is normally safe to connect them in parallel. This is because two 8 ohm speakers in parallel makes the total load impedance 4 ohms. Most HiFi amps are designed to have a total load impedance of 4 ohms or higher, but not lower than 4 ohms. If your amp is not specified for 4 ohms (some are 6 ohms or 8 ohms minimum), then you should consider wiring your two speakers in series.

This diagram helps show why speakers connected this way are called “in parallel”

They are known as being in parallel because, well, they are wired in parallel. Admittedly, I’ve drawn them so they look like being in parallel. However, in practice, we wouldn’t use so many cables and connections. For practical ways of connecting 2 speakers in parallel, see the table below.

If your amplifier has an A and B speaker selector, you can use this for a simple way of connecting two sets of speakers in parallel.

Connect 2 Speakers in Series

To calculate the total load impedance of speakers in series, simply add the impedances together

If both speakers are less than 8 ohms, or the amplifier requires a total load impedance greater than 4 ohms, then it is best to connect the speakers in series. This is because two 4 ohm speakers in series makes the total load impedance 8 ohms. Two 6 ohm speakers in series makes the total load impedance 12 ohms. Most amps work fine with a load impedance of 6-16 ohms.

This diagram helps show why speakers connected this way are call “in series”

As you can see, the two speakers are in “series” with the each other.

How to Connect 2 speakers in Parallel and Series

Below is a table showing how to wire up two speakers in parallel and series for common scenarios. Keep in mind these diagrams are for one amp only (let’s say the left amp), you will need to duplicate this for the right amp also.

If you double click on a diagram you should see a slightly larger version for easier viewing.

Practical Ways to Connect 2 Speakers in Parallel and Series
When all cables are run back to the amplifier location
Parallel: Both speaker cables are connected directly to the amplifier	Series:Join two of the wires as shown separate to the connections on the amp.
When the second speaker needs to be connected off the first speaker
Parallel: Join the cables of the second speaker to the cables on the first speaker	Series: Cut one wire near the 2nd speaker, and connect the 2nd speaker "in series" with the cut wire.
When there is a (long) cable run to be split to go to both speakers
Parallel: Join the cables from both speakers to the cable from the amplifier	Series: Join the two speakers in series, then join this to the feed cable
When the cables from each speaker come back to a wall plate
Parallel: Simply join the terminal as shown	Series: The series connection is made with one join

You may have noticed that no matter which scenario is used, all the parallel diagrams are technically wired the same as each other – if you doubt me, trace the connections with your fingers on any two of the parallel connection methods. You can do the same for the series connections below as they are also the same as each other.

Keep in mind that changing the total load impedance of an amplifier will increase or decrease the power output of the amplifier. Connecting in parallel normally increases the output power, while a series connection normally decreases the power output of an amplifier. See Multiple Speakers Change Amplifier Power for more details.

Each speaker may have a different sensitivity which may mean there will be a level difference between them. For more on this see Understanding Speaker Sensitivity.

Also if the speakers each have a different impedance, then there will be different power levels available to each speaker. For more detail see How Multiple Speakers Share Power. My calculators for Speakers in Parallel and Speakers in Series also calculate the way speakers with different impedances share power.

Summary of Connecting 2 speakers

There are only really two ways to connect 2 speakers to one amplifier – either in parallel or series.

If each speaker has an impedance of 8 ohms or more, then you can generally connect them in parallel.

If each speaker has an impedance below 8 ohms, you should wire them in series.

If you need to switch each set of speakers on or off, or you want separate volume controls, see my articles on connecting multiple speakers, wiring 4 speakers and/or my speaker selector switch summary

Click here to browse 2 way speaker selector switches available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

How do I connect a VCR to a Flat Screen TV

Home Connections

Geoff

-

03/10/2015

162

How do I connect a VCR to a Flat Screen TV

You may still have many video tapes that you like to play but find it hard to connect a VCR to your new flat screen TV. Often this is because you can’t find the right connections on the new TV. This article will explain the different options on how to connect a VCR to a flat screen TV, even if you can’t find the yellow socket.

Basically you need to connect from the “line out” of the VCR to “AV in” of the TV. This needs to be done for both the video and for the audio. Some VCRs have one audio out socket (mono) and some have two audio out sockets (stereo) – we will look at stereo first, and look at the differences for mono later in this article.

Connect a VCR with the Yellow, Red and White Leads

To connect a VCR to most flat screen TVs, you will need a cable with these yellow, red and white connectors. For non European VCRs, you will need a cable with these plugs at each end. For European VCRs, you may need a SCART plug at the VCR end, and these yellow, red and white plugs at the other end to connect to the TV.

The yellow, red and white plugs are often called RCA or Phono plugs. The yellow cable is used for the video signal, the red cable for the right audio, and the white cable for the left audio signal. Many VCRs come with these leads supplied. If you don’t have any, they should be available at most electronic or electrical stores.

If you need a SCART connection for the VCR, make sure the SCART cable is designed for output. If you use a SCART cable made for input, it won’t work as you need an output cable. Some SCART leads or adaptors have a little switch on the SCART plug to allow it to be switched to “IN” or “OUT”. Select “OUT”.

The rear of the VCR

This photo shows the standard connectors on most (stereo) VCRs. If you look closely, on the right hand side are the “line out” sockets (the left hand side is for “line in”, which we don’t use for connecting to a TV). The top right red socket is for the right audio out. The white middle right connector is the left audio out socket. The yellow socket at the bottom right is the video out socket.

The markings or labels on most VCRs are as hard to read as in this photo, so you may need to use a torch to see the markings clearly. Once you have found the line out sockets, it is a simple matter of connecting the yellow, red and white plugs of the connecting cable to the corresponding yellow, red and white line out sockets of the VCR.

The Rear of an Older Flat Screen TV

Older flat screen TVs are easy to connect a VCR to as they have at least one yellow “video in” socket. In this photo you can see it just below the centre of the photo, it is labelled “Video”. Below this yellow socket for video in is the corresponding white and red sockets for the left and right audio in.

Having found the yellow, red and white sockets, it is a simple matter of connecting the corresponding yellow, white and red plugs of the cable connected to the VCR to these sockets.

You may have noticed that in this photo, these sockets are in a section labelled “VIDEO 1 IN”. This normally would indicate that this is the input you need to select on the TV to watch the VCR. Most TVs require you to press “Source” or “Input” on the remote control to select the “Video 1” input signal.

Other TVs might label these inputs “AV” (short for Audio/Video).

Some older TVs might have several AV inputs, normally labelled AV 1, AV 2 etc. Some flat screen TVs have the AV input on the side of the TV.

My TV doesn’t have a Yellow Socket!

I get many questions from people saying they can’t find the yellow socket to connect a VCR into. Don’t worry, I have a solution. But first check the sides of your TV to make sure the designers aren’t trying to trick you by hiding the yellow, red and white sockets up one side.

Other TVs have a little yellow socket (like a headphone socket) often labelled “AV In”. These are designed to allow the yellow, red and white leads from the VCR to connect to the TV via a little adaptor lead.

Some manufacturers provide these adaptors with the TV, other manufacturers assume you will buy one if you need to. If you need to buy one, search for “3.5mm AV lead”. Either way, simply plug the leads from the VCR into the adaptor lead and then plug this lead into the TV.

Don’t worry if you can’t find a yellow socket on your TV to connect a VCR, as many new TVs don’t have one. Manufacturers think there is no need to supply TVs with the ability to connect a VCR through the standard (and old) yellow, red and white sockets. Instead some TV’s let you connect to the green socket, and others require you to use a HDMI input. I discuss each method below.

If there is a Green Socket

At the rear or side of many flat screen TVs there is no yellow socket for “Video In”. But as you can see in this picture, they indicate you can use the green socket instead. Notice on this TV, (and most others) there is only one of the green sockets nominated as “Video in” for you to connect a VCR to.

So for this TV, you would connect the yellow lead from the VCR to the nominated green “Video in” socket. The red and white audio leads from the VCR would connect to the corresponding red and white audio sockets below the blue and red.

Be careful not to fall into the trap of connecting the red audio cable, to the other red socket labelled “Pr” – the right audio will not work if you do this. Also ensure you don’t connect anything to the blue or red video inputs or your VCR picture will be in black and white only.

Note that not all TVs label the “video in” as clearly as in the photo above. Some simply put a yellow circle around the appropriate green socket. Some use a combination of yellow and green. Others label this socket as “Composite Video”.

Composite Vs Component Video

You don’t need to understand this section – it is for those people who like to understand why it is possible to connect a VCR via the green socket.

The green, blue and red sockets labelled Y, Pb and Pr in the photos above are for connecting a DVD player. These three video signals are called “Component Video”. It is the best way of connecting a DVD player if the DVD player doesn’t have HDMI. The green input from a DVD player is basically the black and white picture. The blue and red inputs are for the colour information of the picture. Then the other red and white sockets are for the right and left audio.

The video signal from a VCR has the black and white picture and the colour information all joined together – called composite video.

Modern TVs are clever enough to know when you only have one lead connected with all the information (composite video) or separate leads (component Video). Hence they don’t need to provide a separate input for Composite only. For a more detailed explanation of component video see this article, or this article to learn more about composite video.

Connect a VCR with HDMI only on the TV

Many new TVs do not have any analogue inputs. Therefore you need to use one of the HDMI inputs on the TV. However you can’t connect your VCR directly to the TV. You need a converter box between the VCR and the TV.

The yellow, red and white lead from the VCR plugs into the input of the converter box. The output of the converter box connects to a HDMI lead. The other end of this lead will plug into one of the HDMI inputs of the TV. Note: Some converter boxes also require a USB lead to be plugged into the TV – this is used to power the unit. Other converter boxes receive power from the HDMI connection to the TV.

If you are going to buy a composite(RCA) to HDMI converter consider these tips:

Beware, many on-line searches return two types of converters: a RCA to HDMI converter and the reverse, a HDMI to RCA converter. To connect a VCR to a TV using HDMI, you need a RCA to HDMI converter.
You may also need to buy a short HDMI lead, if you don’t already have a spare one.

Click here to browse RCA to HDMI converters available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

My VCR only has a white audio out

Many VCRs are not stereo, they are only mono. That is, they do not output a left and right audio channel. Instead they only output one single audio channel (mono audio). Therefore, they do not have a red and white audio output (for right and left audio). They only have a white output, for the mono audio. You may remember most old TVs only had one speaker, so the VCR only needed one audio channel (mono).

To connect a VCR with only mono audio to a flat screen TV, simply go from the “audio out” socket of the VCR.

That is the easy bit. How you connect to the TV will depend on the TV.

Some TVs will have sockets on the back like this picture. On the left hand side you should see the Audio right (red) and left (white) input sockets. The left socket is also labelled “MONO”. If your TV is like this, then simply connect the “mono out” from the VCR to the “mono in” of the TV. The TV should direct the sound to both (left and right) speakers of the TV.

If your TV does not have a Mono input, then you have two or three options:

1. You can simply connect the “mono out” from the VCR to the “Left in” on the TV. This will send the sound to the left speaker only. While you might think this is not ideal, you may be surprised that it sounds fine when sitting some distance from the TV. The red cable is not used if connecting to the TV this way – it can just hang on its own behind the VCR and TV.
2. You can use a cheap mono to stereo adapter cable. The single (black) plug is connected to the white audio out of the VCR. Then a normal red and white audio lead is connected from the adapter cable to the right (red) and left (white) audio in sockets of the TV. This will send the same mono audio to both the right and speakers of the TV.
3. You can also use a mono to stereo adapter plug. This plugs straight into the ‘Audio Out” on the back of the VCR. Then a normal red and white audio lead is connected from the two sockets of the adapter to the right (red) and left (white) “audio in” sockets of the TV. This works exactly the same as the lead above – use whichever one is available to you.

Whichever way you connect the mono audio, you will hear the sound through the TV. Keep in mind that many video recordings were probably recorded in mono, so you are not missing much.

Don’t forget to also connect the yellow video lead from the VCR to the TV (as described above).

All Connected but no Picture

I get many questions from people who have connected their VCR to the TV by one of the above methods, but still get no picture. This could be due to a faulty lead or incorrect connections, but it could also be dirty heads on the VCR.

There is some simple tests to know if you have it all connected correctly. Insert a pre-recorded tape in the VCR and press play. Select “AV in” or similar on your TV

1. First off, do you have sound? If so, you are probably connected correctly. At least the sound is working so you know you have selected the correct input on the TV.
2. If you have sound but no picture, try stopping the tape and starting it again while looking at the screen. Do you see the little Play and stop icons? (some VCRs don’t display these). If you see the control icons on the TV, then you have the connections correct.
3. Press stop on the VCR and press the “menu” button on the VCR remote (some older VCRs don’t have a menu). When you press menu, you should see it appear on the TV. If you do, then the connections are correct.

If you have sound, and see either the control icons and/or the menu on the TV, then the connections are correct. It probably means the VCR has dirty heads. This is very common with older tapes. If you do an internet search for “clean VCR heads”, you get to choose from over 3 million results. If any of those sound too technical for you, you can try playing the tape for a few hours. Quite often the gentle rubbing effect of the tape passing over the heads will eventually clean the heads. Be aware that no matter how you clean the heads, the next tape you insert might clog them up again – if the new tape has dirt or mildew on it.

If any of the above tests are negative, then you should cover the basics like try a different set of cables.

If possible, try using the same cables to the TV but connect them to another VCR or DVD player. This will confirm the cables are OK and the TV input is working and correctly selected.

There can be other issues with your VCR that prevent it showing a picture. There can be mechanical or electronic failures. A common fault is the rubber belts and capstans perish. These types of faults will require a proper service of the unit.

If you still have a problem to connect a VCR to your TV, list the details of the equipment and how you tried to connect them in the comments box below, and I’ll try to help you work through the issues.

Understanding Audio Levels

Understanding Audio

Geoff

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18/02/2012

157

A basic understanding of the general audio levels mentioned in this article will help you avoid the common mistakes often made when connecting audio devices together. We are going to talk about three different general levels of audio signals. The names of the three general audio levels are speaker level, line level and microphone level. For simplicity, the different audio levels are described in volts. For an understanding of decibel levels used in audio, see the articles on decibels starting here.

Speaker Level

A speaker needs a few volts of electrical audio signal to make enough movement in the speaker to create a sound wave that we can hear. Small speakers need only a few volts, but large speakers need 50-100 volts to make a loud sound.

Line Level

A speaker is connected to an amplifier. Think of your HiFi amplifier at home. What plugs into your amplifier? DVD player, CD player, radio/tuner, video camera. All these devices plug into the “line in” or “Aux in” of your amplifier. “Line IN”, “Aux IN” and “Line OUT” all have an electrical audio signal at line level. You are probably aware of the standard red and white leads used in HiFi equipment, these all use line level. Other plugs are also used for line level. Line level is about half a volt to one (½ – 1) volt. It is the job of the amplifier to amplify the half to one volt of line level, up to the 10 volts or more of speaker level.

Note: A common error is to connect plugs and sockets together just because they fit. Don’t assume audio level based just on the type of plug being used. The same type of plug can be used for different purposes (and different audio levels).

Microphone Level

Ok , so we have line level (about ½ – 1 volt) which goes into an amplifier to make it up to speaker level (about 10 volts or above). What audio level do you think Mic level is? How much voltage do you think comes out of a microphone, as a result of you speaking into it? Answer: Stuff all!

The output voltage of a microphone is very low. It is measured in milli-volts, that is 1/1000th of a volt. A mic can give as little as 1 mV, or upto 100 mV, depending on how loud you speak into it. That is not very much. So what do you think is going to happen if you plug a mic directly into the line in of an amplifier? Answer: A very low level of muffled sound if anything.

Mic Pre-amps

The amplifier is wanting line level, ½ – 1 volt to produce enough signal to make the speaker work properly. But the mic is only producing milli-volts. So what is needed is a small microphone amplifier that amplifies the audio level from mic level to line level. This should go between the microphone and the amplifier. Because it is for the microphone and it is before the main amp, it is called a mic pre-amp. A mic pre-amp amplifies the milli-volts from a microphone up to line level.

Mic pre-amps are normally built into devices designed for connecting to a microphone. Equipment like an audio mixer, a digital recorder, a video camera or a computer – all these may have mic level inputs as well as line level input, or just a mic level input. .

Audio level microphone level, line level

The picture on the right shows for each input on this mixer there is a line level input (labelled Line 3 and Line 4), as well as a microphone pre-amp (labelled MIC PRE).

Obviously a microphone plugs into the mic input, as the mic inputs are connected to the in-built mic pre-amps.

A line level device would obviously plug into the line in socket.

But what if your mixer (or camera/recorder) only has a microphone input, and you need to connect a line level source to it? This would result in the line level (½ – 1 volt) being connected to the input of the mic pre-amp. The trouble is, the mic preamp is expecting only a few milli-volts. The resulting sound will be very distorted as the mic pre-amp is completely overloaded.

Attenuators

So how can we do this? How do we connect a line level to a mic level input? We have to reduce the line level down to mic level. The technical word for this is to attenuate the signal. As an amplifier amplifies, or boosts the signal; an attenuator attenuates, or reduces the signal.

You can buy attenuators at a music shop, they are called DI boxes. DI stands for Direct Injection or Direct Input, meaning you can directly inject a line level into the mic input without any problems. It is also possible to make an attenuator, possibly with variable attenuation, to cope with different levels. It is also possible to buy or build a fixed attenuator in a cable (see my Decibel Calculator for Audio for more details). This is a cable with resistors built-in to the plugs to attenuate the line level down to mic level – this is very useful for a video camera or portable digital recorder.

Click here to browse DI Boxes available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

Audio Level Summary

There are three main audio signal levels: mic level (millivolts), line level (around 1 volt) and speaker level (around 10 volts or more). The rule is, only plug speakers into the speaker socket of an amplifier; only line level into the line in of any equipment; and only mic level in the mic input of your mixer, camera or laptop. The most common cause of audio distortion comes from not understanding the different levels, and how to connect them all together.

Practical Example 1

Scenario: A keyboard (electric piano) located on the stage needs to connect to a mixer located at the back of the hall, with a microphone multi-core cable connecting between the two.

Issue: The output of the keyboard is at line level, and the microphone input at the mixer requires mic level. (There is also the issue of different plugs and balanced/unbalanced inputs but these are the topics of other articles).

Solution: Use a basic DI box available from most music or electronic stores. A DI box acts as an attenuator which reduces the line level of the keyboard to mic level for direct connection to the mixer (via the multi-core cable). The DI box also overcomes the issues of matching plugs and going from unbalanced to balanced – so this is a perfect solution. This solution also works for connecting electric guitars, electronic drums and DVD players.

Practical Example 2

Scenario: The output (line level) of an audio mixer needs to connect to a digital camera or digital recorder which only has a microphone input.

Issue: The output of the mixer is at line level, and the microphone input of the camera/recorder requires mic level.

Solution: A basic DI box could be used, but this would require an input lead, and output lead and the DI box – a lot to carry in your camera bag. A neater solution is to have a lead with a 40dB attenuator built into it. This will reduce the line level from the mixer by a factor of 100, which will bring the line level down to a reasonable mic level to connect directly to the microphone socket of the camera/recorder.

This article is based on one I originally wrote for my friends at CamcorderUser.net, and has been refined by their helpful comments.

Speakers in Parallel Calculator

Geoff

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22/03/2014

154

Jump Straight to Calculator

The calculator below is useful in determining the total impedance of speakers in parallel. It also calculates how the power is shared between the speakers.

If all the speakers have the same impedance, the calculation is relatively easy.

Simple Impedance Calculation for Speakers in Parallel

If all the speakers in parallel have the same impedance, then simply divide the impedance by the number of speakers in parallel.

Example 1: Four 8 ohm speakers in parallel: 8 divided by 4 = 2 ohms.

Example 2: Two 4 ohms speakers in parallel: 4 divided by 2 = 2 ohms.

Not so Simple Calculations for Speakers in Parallel

For calculations involving speakers in parallel with different impedance, the following formula is required (it can be used with speakers of similar impedances too).

If you have a calculator with 1/x button then this calculation is not too difficult. If you don’t have that function on your calculator, or if you don’t like formulas, check out the calculator below.

Using the Calculator

The calculator can be used for 2, 3 or 4 speakers wired in parallel.

Simply type the impedance of each speaker into the white boxes (or use the drop-down values). Use N/A for unused speakers in this calculator. The total impedance will be calculated for the entered speakers.

Also calculated for each speaker is its percentage share of the amplifier’s output power. This is useful as power sharing is a consideration when using speakers with different impedance.

“Power Differential” is the final calculation. This calculates in dB (decibels) the power level difference between the highest and lowest power as it is shared across the speakers. This shows the power level difference when using speakers with different impedance.

Amplifier Power Calculator

The bottom section of the calculator helps in matching the speaker combination with your amplifier. This is not necessary if you only want to know the total impedance and/or the power ratios.

However if you are connecting these speakers to your amplifier, it may be helpful to input the amplifier power and the associated speaker impedance. In the specifications for your amplifier, it should say something like:

Amplifier power: 80 watts continuous average power @ 4 ohms (2 channels driven, THD 0.08%, 20Hz-20kHz)

This tells you the maximum continuous power the amplifier will deliver into a 6 ohm load is 80 watts. In the calculator below, for this example, you type in 80 for the power and 6 for the impedance. Be advised, some specifications state RMS power rather than continuous power. These are effectively the same.

The calculator will display the effective power of the amplifier for the calculated total impedance of the speakers in parallel. Also displayed (under each speaker’s power %) is the actual maximum power the amplifier will supply each connected speaker. A comment on the suitability of the calculated total impedance for your amplifier is also provided.

Note: the calculator is best viewed in landscape mode on phones and small screens

Download Calculator
as Excel File

Prices in US$

Note: the calculated output power for the amplifier is based on a theoretical “ideal” amplifier. In practise, your amplifier may produce slightly more or less power.

Need to know more?

This calculator will help you understand the total speaker load on your HiFi amplifier. For a better understanding of this and what to do about it, read the articles How do I Connect Multiple Speakers to my HiFi Amplifier and How to wire four HiFi speakers or How to connect 2 speakers to one amplifier or watch the video in the article Understanding Speaker Impedance.Also see How Multiple Speakers Share Power for further details about the percentage power calculations. For more details about the effective amplifier power at higher impedance loads, see How Impedance Changes Amplifier Power.

If you need to calculate the impedance and power sharing of speakers in a different configuration, you can use my Speakers in Series Calculator, or the Speakers in Series/Parallel Calculator.

Please Note: all these calculations are for connecting manufactured speakers (boxes). They are not used when building your own speaker boxes and connecting multiple speakers in a cabinet using a crossover circuit. A crossover splits the signal into different frequencies for each of the speakers and makes the total impedance calculation complex (as impedance is frequency dependent). That is why speaker designers get the big money, and as installers we benefit from their expertise.

If you need further advice on connecting speakers (boxes) in parallel, please read the FAQs before submitting your question. You may also find an answer in the comments below.

Understanding Distributed Speaker Systems

Understanding Audio

Geoff

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08/04/2014

152

Understanding Distributed Speaker Systems

Distributed speaker systems are also known as “100 volt line” or “70 volt line” speaker systems. They are used extensively where multiple speakers are required. Distributed speaker systems are commonly used in airports, shopping centers, schools, churches, clubs, offices, car-parks, sports grounds and anywhere multiple speakers are required. They can also be used in homes for background music systems.

Advantages of Distributed Speaker Systems

The main advantages of distributed speaker systems are:

No need for complicated calculations of total speaker impedance – simply add together each speaker’s wattage (see below for more details)
Many speakers can be connected to an amplifier.
Extra speakers can normally be added to the system
The volume of each speaker can be adjusted independent of the main volume (so the toilet speakers are not as loud as the foyer speakers).
Smaller cables can be used. Distributed speaker systems use much less current through the speaker cables
Longer speaker cables are possible with minimal line loss. Cables runs can be 100’s of metres or 1000’s of feet.

Disadvantages of Distributed Speaker Systems

The main disadvantages of distributed speaker systems are:

Each speaker requires a step-down transformer
The transformers affect the quality of the sound – typically the lower frequencies are not transferred as well as a speaker system without transformers.
Without using expensive transformers, use is often limited to paging, voice and low level (background) music installations.

Distributed Speaker Systems Overview

The basis of distributed speaker systems is similar to the way electricity is distributed. Power stations use step up transformers to distribute power as high voltage, which means low current, and therefore low line losses and thinner cables. Each town and/or street then converts this high voltage/low current down to low voltage/high current (through step down transformers) for use in your home.

Distributed speaker systems use a similar principle. The amplifier normally has a step-up transformer built into it, producing a high voltage/low current output. Then each speaker has its own step down transformer to convert the signal back to low voltage/high current. This allows the cable to be very long without having any significant line losses.

100 Volt Line Speaker System

The most common “high” voltage used in distributed speaker systems is 100 Volts. In many countries distributed speaker systems are known as “100 Volt line” speaker system. In a 100 Volt line speaker system the output of the amplifier is marked “100 volt”. Indeed at full output, the amplifier puts out 100 volts RMS. Each speaker then has a transformer to reduce the 100 volt line level down to normal speaker level.

70 Volt Line Speaker System

In North America the most common “high” voltage for distributed speaker systems is 70 Volts. This is because years ago, some states had laws stating that any cable with a maximum voltage greater than 100 Volts peak had to be installed in conduit. This was time consuming and costly to install. So they developed a system where the output voltage of the amplifier was a maximum of 100 Volts peak. This equates to 70.71 Volts RMS. This is commonly known as a “70 Volt line” speaker system. The principle is the same as for 100 volt line systems, but uses a maximum output voltage of 70 Volts. While 70 volt line systems are still the most common in the USA, some 100 volt lines systems are being used.

50 Volt Line and 25 Volt Line Speaker Systems

Less common, but still seen on some amplifiers and speakers are 50 volt line or 25 volt line settings. The principles are the same for all voltages, but the lower the voltage, the more current, therefore the shorter the maximum cable length without significant line losses.

In practice, many commercial amplifiers and speakers have multiple taps. They may have 100 and 70 Volts, or 70 and 25 Volts, as well as 4 ohm and 8 ohm outputs for normal speakers (without transformers). Normally you should only use one output of a amplifier, that is, either the 100 volt line output, or the 70 volt line output or the 8 ohm output, not all at the same time.

Transformers

Every speaker in distributed speaker systems needs to be connected to a step down transformer. This converts the high voltage level down to normal speaker level.

One side of the transformer normally has a common (or “0 volts”) and a 4 ohm and 8 ohms connection. An 8 ohm speaker would be connected to the common and 8 ohm taps, while a 4 ohm speaker would be connected to the common and 4 ohm tap.

Most transformers have a selection of input taps. The example in this picture has taps for 20 Watts, 15 Watts, 10 Watts and 5 Watts. The feed cable is connected to the common and any one of the other taps. This allows the relative volume of the speaker to be set during the installation. For example the speaker in a high noise room might be set on 20 Watts, while the speaker in a small, low noise area might be set on 5 watts. Alternatively, the distance between the speaker and the target audience might be different, so the speakers further away can be set at a higher power tapping (or the close speakers at a lower power tapping). To help in determining the correct tap for each speaker in every situation, see my SPL calculator for distributed speaker systems.

All amplifiers designed for use with distributed speakers systems have a step-up transformer built-in. It is also possible to add an external transformer to an amplifier without an integrated transformer. Simply use a speaker transformer in reverse – that is, connect the common and 8 ohm transformer connection to the common and 8 ohm speaker output of the amplifier. Just make sure the amplifier and transformer are rated with enough power to drive all the speakers to be connected (see Connecting Multiple Speakers below).

Amplifiers

As stated above, most amplifiers designed for distributed speakers systems have the output transformer built-in. They may have various outputs for 100 volts, 70 volt and/or 4 or 8 ohms (for normal speakers).

Most 70 volt amplifiers or 100 volt amplifiers also have an input mixer built-in. This allows convenient connection of microphones and line level inputs. Ensure the model you use has sufficient inputs for your current needs, and perhaps some spare inputs for the future.

For multi-zone systems, you can purchase an amplifier with 2 or 4 amplifiers and transformers built in the one box.

Click here to browse 70V/100V amplifiers available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

Speakers

Any speaker can be used in a distributed speaker system, as long as a step-down transformer is used. Many manufacturers produce speakers with integrated transformers for use in distributed speaker systems.

Ceiling Speakers

Ceiling speakers are used in many distributed speaker system installations to cover large areas and/or multiple small rooms or areas. The speaker cable is normally connected directly to the transformer. To change the power settings you need to connect the speaker cable to a different transformer tap. In the speaker pictured, this is a simple matter of moving the speaker wire to a different terminal connector.

Click here to browse 70V/100V ceiling speakers available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

Wall Mount Speakers

100 volt box speaker for distributed speaker systems

Wall mount 70V100V speakers come in all sorts of shapes and sizes. Many manufactures make a version of their cabinets with an integrated transformer. Connections are often by some form of speaker terminals. To change taps, simply rotate the switch to the desired power setting. Often these switches also have a position for 8 ohms (bypassing the transformer) – this makes them very versatile speakers for the installer. Wall mount speakers (which can also be mounted from a ceiling) are used where ceiling speakers aren’t practical, or where higher sound levels are required.

Click here to browse 70V/100V wall mount speakers available from Amazon

Disclosure: If you buy through this link Geoff receives a small commission from Amazon

Horn Speakers

rear of horn speaker for use with distributed speaker systems

Horn speakers are very efficient, but not very good quality. They are mostly used outdoors when coverage of a large, or high noise, area is required. For example in car parks, sports grounds, school yards and other outdoor areas. In the picture shown, the rear of the horn has a selector switch which needs a flat bladed screw-driver to operate. This is useful to reduce the likelihood of inadvertent changing of the settings after the install.

Connecting Multiple Speakers

This is the fun bit, because there is no need to calculate the total impedance. To connect multiple speakers in distributed speaker systems, just wire them all in parallel and add up the total watts.

Example 1: A PA amplifier is rated at 120 watts @100 volt line. Therefore you could connect:

20 x 5 Watt (100 volt) ceiling speakers (total 100 Watts), or
40 x 2.5 Watt (100 volt) ceiling speakers (total 100 Watts), or
10 x 5 Watt (100 volts) ceiling speakers and 20 x 2.5 Watts (100 volt) ceiling speakers (total 100 Watts), or
any combination of speakers that add up to no more than 120 Watts.

Example 2: A small church has a small 25 Watt (70 Volt) PA amplifier with 4 small speakers mounted in the church (2 down each side). They now want to add a speaker in a separate room for an overflow and creche area.

4 existing speakers can be wired at 2.5 Watts (70 Volt), total of 10 Watts
A new box speaker can be wired at 10 Watts (70 Volt), this allows it to be louder than any of the small church speakers (since the creche area has much more ambient noise levels).

As shown, it is easy to add the individual speaker watts together. This is much easier than calculating the total impedance.This makes installation much simpler.

Calculating Watts from Speaker Impedances

Sometimes manufacturers of speakers designed for distributed systems only mark their speakers with the impedance of each tap, rather than the Watts. Also, many impedance meters tell you the impedance, and you need to calculator the wattage.

In either case, you can use this simple calculator:

Tips for Using Distributed Speaker Systems

Following are some practical tips for installing distributed speaker systems:

Keep all the speakers in phase. This means the the “O volt” or the “Com” of the amplifier speaker terminal should be connected to the “O Volt” or “Com” of each speaker transformer.
It is good practice to design distributed speaker systems to use up to only 80% of the amplifier’s total available power. For example, a 120 Watt PA amplifier should only be connected to a maximum of around 100 Watts of speakers. This helps avoid the amplifier’s transformer distorting from saturation (overload), allows for inefficiencies in the system, and allows an extra speaker to be added if required in the future.
When designing distributed speaker systems, calculate the total watts of the speakers, and select an amplifier larger than required. For example, If an install requires 10 speakers at 5 Watts each (total load of 50 Watts), a 60 Watt amplifier could be used, but selecting a 100 Watt or 120 Watt amplifier will allow speaker taps to be changed or extra speakers added in the future. It is a relative small increase in price to up-size the amplifier before purchase, rather than have to buy a new one later.
When selecting speakers, chose a higher power one than required. For example: If a 5 Watt ceiling speaker is required, chose a 10 Watt or 15 Watt speaker and use the 5 Watt tap on the transformer. This again reduces the likelihood of overloading cheaper transformers, and gives the ability to increase the power level (volume) if required.
When connecting many speakers, it is good to have multiple feed cables. For example; if connecting 60 speakers, it is possible to use one speaker cable run and loop in and out of each speaker. However it is better to have several feed cables to smaller groups of speakers. This way if a fault occurs, it is easier to isolate which feed the fault in on. Also the total load (and cable loss) is shared by each cable run. If you have long cable runs, see my Cable Loss Calculator to ensure you use the right size cable.
It is possible to get some speakers with a built-in attenuator to control the volume of the speaker. This is useful in situations when you want the listener to control the volume. For example in a creche. It is also possible to get external attenuators to control the volume in a room or for an individual speaker.
If possible, measure the impedance of each speaker feed cable before connecting the amplifier. This is best done with an impedance meter. If installing a number of distributed speaker systems, an impedance meter is very useful.
Don’t connect a 4 ohm or 8 ohm speaker directly to a 100 volt line or 70 volt line speaker cable. Apart from severely overloading the speaker (and possibly burning it out) a 4-8 ohm speaker effectively puts a short circuit on the speaker line and overloads the amplifier. See the calculations below for the mathematical explanation of this.
If a 100 Volt line amplifier is overloaded, connecting the load to the 70 Volt line effectively halves the load on the amplifier and it will not be overloaded. However the maximum power to each speaker (and therefore the speaker output) is reduced by 3dB.
- Example 1: The total watts of all the (100 Volt) speakers totals 200 Watts. If connected to the 100 Volt line speaker terminals of a 120 watt (100 Volt) amplifier, the amplifier will be overloaded. Connect the same speakers to the 70 Volt line terminals of the same 120 watt amplifier and the amplifier will only see a load of 100 Watts.
- Example 2: The total watts of all the (70 Volt) speakers totals 50 Watts. If connected to the 70 Volt line speaker terminals of a 40 watt (70 Volt) amplifier, the amplifier will be overloaded. Connect the same speakers to the 50 Volt line terminals of the same 40 Watt amplifier and the amplifier will only see a load of 25 Watts.
- You can use the calculator above to see this by selecting the different system voltages. For those whose like to know, the mathematical explanation of this is below.

Summary

Distributed speaker systems are ideal for multiple speaker installations. They allow long speaker cables and calculation of the total load is easy. Distributed speaker systems are normally mono (not stereo). They are mostly used for paging and background music situations. Although normally used for commercial installations, they can be used in domestic installations for background music systems

Below are some of the major calculations used with distributed speaker systems (you can stop reading now if you are not into calculations).

Calculations for Distributed Speaker Systems

The following calculations are for those who like to understand the mathematics behind the principles outlined above. You don’t need to understand these calculations to use distributed speaker systems, but it will help you understand and design systems better.

Several principles of distributed speaker systems have been outlined above. A mathematical explanation of each principle is now given under the following sub-headings:

Adding the Power of Each Speaker

As an example, four 5 Watt speakers are connected together (in parallel) to a 100 Volt line amplifier.

The simple way to calculate the total load is to add 5 + 5 + 5 + 5 = 20 Watts.

The harder way (which is why its not normally done) is to calculate the impedance of one speaker, and then calculate the total impedance of 4 such speakers in parallel, and then calculate the total power.

So the impedance of a 5 Watt speaker on a 100 volt line:

$Impedance={\Large\frac{Volts ^2}{Power}=\frac{100 ^2}{5} = \frac{10,000}{5} =}\, {\large 2,000}\, ohms$

That’s right, the impedance of a 5 Watt speaker with a 100 volt transformer is 2,000 ohms. Now to calculate the total impedance of four of these connected in parallel:

$\frac{1}{R_{Total}}= \frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}+\frac{1}{R_4}$ so $\frac{1}{R_{Total}}= \frac{1}{2000}+\frac{1}{2000}+\frac{1}{2000}+\frac{1}{2000}=\frac{1}{500}$

therefore R (total) = 500 ohms.

Now the total power of 100 Volts with a total impedance of 500 ohms can be calculated:

$Power={\Large\frac{Volts ^2}{Impedance}=\frac{100 ^2}{500} = \frac{10,000}{500} =}\, {\large 20}\, Watts$

Low and behold, that is the same as simply adding the speaker watts together – which is much simpler!

Changing the Amplifier Connection Halves the Load

Example 1: The total impedance of 200 watts of 100 Volt speakers can be calculated:

$Impedance={\Large\frac{Volts ^2}{Power}=\frac{100 ^2}{200} = \frac{10,000}{200} =}\, {\large 50}\, ohms$

Now look what happens when that same 50 ohm speaker load is connected to the 70 Volt terminal of the amplifier:

$Power={\Large\frac{Volts ^2}{Impedance}=\frac{70.71^2}{50} = \frac{5,000}{50} =}\, {\large 100}\, Watts$ .

Amazing, the same 50 ohm load draws 200 watts of power on a 100 volt line system, but only 100 watts on a 70 volt line system.

Example 2: The total impedance of 50 watts of 70 Volt speakers can be calculated (remember 70 Volt line is actually 70.71 Volts):

$Impedance={\Large\frac{Volts ^2}{Power}=\frac{70.71 ^2}{50} = \frac{5,000}{50} =}\, {\large 100}\, ohms$

Now look what happens when that same 100 ohm speaker load is connected to the 50 Volt terminal of the amplifier:

$Power={\Large\frac{Volts ^2}{Impedance}=\frac{50^2}{100} = \frac{2,500}{100} =}\, {\large 25}\, Watts$

This principle is very handy to the installer if the power required by the speaker load is greater than what the amplifier can deliver. Simply move to the lower line voltage speaker connection (on the amplifier) and the power drawn is halved. The maximum power to each speaker is also halved, so the speaker output is halved, or reduced by 3dB, but the amplifier will not be overloaded.

A 8 Ohm Speaker will Overload a Distributed Speaker System

In the examples above we saw the speaker impedance of distributed speaker systems is reasonably high. For example a 5 watt speaker on a 100 Volt line has an impedance of 2,000 ohms. Even a 125 Watt load of 100 Volt speakers is 80 ohms. So imagine the load if the total impedance is only 8 ohms. It should be 10 times the load right? This scenario can be calculated:

$Power={\Large\frac{Volts ^2}{Impedance}=\frac{100^2}{8} = \frac{10,000}{8} =}\, {\large 1250}\, Watts$

That’s right, connecting a low impedance speaker (4 or 8 ohms) to distributed speaker systems will drastically increase the load on the amplifier.

How do I connect my Flat Screen TV

Home Connections

Geoff

-

22/04/2012

119

Connecting your TV is not as hard as it looks. All the sockets on the back and up the side of a flat screen TV can be imposing, but tackling them one by one reduces it to a simple task. I say simple, because you don’t need to use all of them – just the ones best suited to your equipment.

Choosing the Best Connections

So which cables, plugs and sockets should you use? It depends on what outputs your other devices have. Below is the basic hierarchy for cables and connectors when connecting devices to your flat screen TV. For more info on these connections, see the reference articles on HDMI, Component video, S-video, and Composite video.

Order	Connection	Comment
1st Choice	HDMI	Best quality digital picture and digital audio in one cable
If no HDMI	Component Video + Audio	Best quality analogue picture, plus analogue audio – requires five cables. Normally you would have all five cables joined into one, or use a 3 core red, green blue for the video and a separate red and white RCA (phono) cable for audio
If no Component Video	S-Video + Audio	Not as good as Component Video but better than composite video, not available on all flat screen TVs. Also requires a RCA (phono) lead for the analogue audio
If no S-Video	Composite video + Audio	The most basic video connection, being phased out on newer equipment. Uses the common yellow, red and white connections. Use the yellow cables for composite video and the red and white cables for analogue audio

Let us use a DVD player and a VCR as an example: if the DVD player has a HDMI output, then use HDMI to connect to the flat screen TV. That’s it, done. If the DVD doesn’t have HDMI, then use the green, blue and red component video connections with the red and white audio leads. A VCR probably doesn’t have HDMI or Component video connections, so you can use the S-video cable with the red and white audio leads. If it doesn’t have S-video, then use the basic yellow composite video cable with the red and white audio leads. Some manufacturers make a red and black coloured lead for audio – use this just the same as a red and white lead. In fact the colours don’t really matter at all, they are simply there to assist you in connecting the output sockets of the DVD player to the correct input sockets.

All about the Sockets

Let us look at the back of a typical flat screen TV to see how to use each socket.

The best quality, and the simplest connection is HDMI. If you can connect all your devices using HDMI, then you probably don’t need to worry about all the other connections. If you connect a device to HDMI input 1, then use the “input” or “source” button on the flat screen TV remote control and choose HDMI input 1 to watch that program.The next best quality is to use Component video. You need three cables for the video (red, blue and green) and two for the audio (red and white). Simply connect the green socket from the DVD player to the green socket on the flat screen TV. Do likewise for the blue and red connectors. Then use the red and white audio connectors to connect the audio. If you connect a device to Component video 1, then use the “input” or “source” button on the flat screen TV remote control to choose Component 1 input to watch that program.After HDMI and Component video, the next best video connection is S-video. It is not always available, but if it is available, it gives better quality video than Composite video. It may also be difficult to find a S-video cable, but it is worth it if you can. You also need to connect the red and white for the audio. Some flat screen TVs have the S-video input labeled as S-video, while others will have it labeled as AV1 or AV2.Finally, if no other connections are able to be used, you can use the basic Composite video. This is most common when connecting a VCR to your flat screen TV. This uses the yellow connection for the video, and the read and white connections for the audio. Most flat screen TVs will call this input AV1, AV2 or video in.A lot of manufacturers are not providing a separate connection for composite video. That is, they are not providing the “yellow” socket that was common previously, like in this image:

The solution for this is usually to use the Green “Y” socket. In the case of this example, it is also labelled “composite”. This means you would connect the yellow lead from your VCR to the green socket on this TV. With some TVs, you may need to go into the menu and tell it that you want to use the component input as a composite input, but a lot of TVs will automatically detect this. For a more detailed description, see the article How to connect a VCR to a flat screen TV. The PC input is used to connect a laptop or desktop computer to your flat screen TV. A “Mac” computer can also use this input with the appropriate adapter plug (normally used at the computer end). This 15 pin connector is for RGB video only, so a separate cable is required for audio.The audio out sockets can be connected to an external amplifier. This will be covered in a future article.European models of flat screen TVs also have SCART connectors.

These 21 pin sockets can carry composite video, RGB video and audio. You will notice on the model in this picture that the top SCART connector accepts Composite video and audio (AV), while the bottom connector accepts RGB video and audio.

Connecting to the Outside World

The “ANT IN” connector is where the cable from your antenna plugs. If you have cable TV, this will plug in here instead. If you have a PVR (Personal Video Recorder) then the antenna/cable lead will normally plug into the PVR. From the PVR will be another antenna cable to connect to the antenna in socket of your flat screen TV. More details of connecting a PVR will be in a future article.The “LAN” connector (extreme right in the picture) is where a internet/network cable is connected. This is required for “Smart” TVs to allow you to view videos and other content on the internet directly on your flat screen TV. Some Smart TVs have a wireless network built-in, if you use this you won’t need the wired internet connection.

Power On

Once everything is connected you can connect the power lead and turn the power on. Many flat screen TVs have a separate on/off at the bottom or at the rear of the screen. Not knowing about this switch or not turning it on has caused many people to think their new flat screen TV is faulty – so beware of this trap. It also can take 3-5 secs for flat screen TVs to turn on (show a picture) once you press the “power” on button of the remote control.

Practical Points

Before starting to connect all you equipment together, sit them in the location you want them to be. This way you will be able to work out how long each interconnecting lead will need to be.
The correct length of interconnecting cables is a balance between aesthetics, practicality and availability. Aesthetically it is good not to have long cables bundled up making a mess behind all the equipment. Practically, you need to have the cables long enough so that you can move (pull out or turn around) each device without the cables pulling out. The availability of different lengths may be the deciding factor, but err on the side of not having the cables too short.
Some retailers of flat screen TVs charge a premium for HDMI cables – often in the $100-$200 range. This is because they can make little or no profit from selling flat screen TVs and so try to make a greater profit on the accessories. Shop around, short high speed HDMI cables can often be bought for only $10-$20.
Most flat screen TVs also have some input sockets on the side of the screen. These are meant to be a convenient way of connecting portable devices like cameras or laptops. They can also be used for connecting permanent devices if required – but the cables are difficult to hide.
Many flat screen TVs have the ability to rename the input labels. This means that instead of choosing between HDMI1 and HDMI 2, the input on the screen menu will be labelled DVD player and PVR (for example). If you have more than one external device, this is an easy way for all users to easily choose the right input. You will need to look at the users guide for your particular flat screen TV to see how to do this.

Summary

Connecting your flat screen TV is not too difficult. Take each device one at a time. If possible, use HDMI. If HDMI is not an option, follow the table at the top of this article to deliver the best possible picture quality. Give it a go, you may be surprised how simple it is.If, after reading the article, you still have problems connecting your flat screen TV, let us know via a “comment” below. Please include model numbers of all equipment you are connecting so I can try to download their manuals and determine the best way to help you.

Speaker Selector Switch Summary

Home Speakers

Geoff

-

02/10/2014

60

Speaker selector switches are the most common item bought from Amazon through this website (with over 1000 units sold). Therefore I thought it is high time to look a little deeper at the different speaker selectors and the features available. I also present a table (or 3) outlining the models, features and price of what is available through Amazon.

The main reason speaker selectors are used is to distribute sound to multiple speakers while protecting the amplifier from too much load (due to too many speakers).

Please note, speaker selector switches are designed for multi-room installs in a home or small low power installs (like an office or cafe). They are generally suited for low power (under 100 watts) amplifiers. They should be not be considered in a commercial install or for use with high output power amplifiers.

For a more detailed explanation of the issues regarding speaker load and impedance, see my article on connecting multiple speakers to your HiFi. For an explanation on using the various type of speaker selectors and how to wire them, see my article on wiring 4 speakers .

For a good overview on speaker impedance and how speaker selector switches help overcome the issues, watch the video (particularly the 2nd half) in Understanding Speaker Impedance.

Protecting the Amplifier with a Speaker Selector

A speaker selector switch should ensure the total impedance of all the connected speakers is not below the minimum load impedance the amplifier is designed to drive – typically 4-16 ohms for HiFi amplifiers. There are three main technologies employed by manufacturers of speaker selectors to protect the amplifier from overloading due to a low load impedance:

1) Series-Parallel: Used mostly on 2 zone and 4 zone speaker selectors. On a 2 zone speaker selector using this method the speakers are connected in series when zone A and B are selected. If only either zone is connected, then just that zone is connected directly. For example: If using two 4 ohm speakers, selecting either zone will present just that speaker (4 ohm) as the total load to the amplifier. If both zones are selected, the speakers will be connected in series (4 + 4 = 8 ohms total load). On a 4 zone speaker switch using this method, zones C and D are also connected in a similar fashion. So zones A and B are connected in series when both are selected, and zones C and D are connected in series when both are selected. Then zones A and B, and zones C and D are connected in parallel with each other when all four are selected. A four zone speaker switch using series-parallel connections for impedance protection should not be used with 4 ohm or 6 ohm speakers, as the total load can be as low as 2 ohms – too low for most domestic amplifiers.

Below is a table showing the total impedance for the various combinations of selected zones when using a 4 zone speaker selector switch employing series-parallel impedance protection with 4 ohm, 6 ohm or 8 ohm speakers.

Zones Selected	Total Impedance with 4 ohm speakers	Total Impedance with 6 ohm speakers	Total Impedance with 8 ohm speakers
A or B or C or D	4 ohms	6 ohms	8 ohms
A + B or C + D	4 + 4 = 8 ohms	6 + 6 = 12 ohms	8 + 8 = 16 ohms
A+C or A+D or B+C or B+D	4 // 4 = 2 ohms	6 // 6 = 3 ohms	8 // 8 = 4 ohms
A+B+C or A+B+D or A+C+D or B+C+D	8 // 4 = 2.6 ohms	6 // 3 = 2 ohms	6 // 8 = 5.3 ohms
A + B + C + D	8 // 8 = 4 ohms	6 // 6 = 3 ohms	16 // 16 = 8 ohms

As seen in this table, using a 4 zone speaker selector switch employing the series-parallel method of impedance protection is not good for 4 ohm or 6 ohm speakers, these types should only be used with 8 ohm speakers.

2) Series Resistor: this is used on lower cost speaker selector switches. It normally means there is a resistor (3-6 ohms) wired in series with the speakers. This gives the total circuit a minimum resistance which will protect the amplifier. However, this resistor gets hot at higher volume levels. That is why most speaker selectors using a series resistor for impedance “matching” have air vents in the chassis. Obviously there is some energy lost in these resistors as they produce the heat. Most speaker selector switches employing a series resistor have a “protection” or “impedance protection” switch. This switches the series resistor in and out of the circuit. When you are using more than one set of speakers at the same time, the “protection” switch should be activated. When only one set of speakers are being used, or you are using impedance matching volume controls, the series resistor can be switched out to allow “direct connection” with no losses.

3) Impedance Matching Transformer: this is used on higher power and higher cost speaker selector switches. An impedance matching transformer inside the speaker selector multiples the impedance of each speaker which effectively keeps the total impedance around the same as any of the individual speakers (providing the speakers are the same impedance as each other). For example: a 4 zone speaker selector with an impedance matching transformer would multiple each of the 8 ohm speakers by four (making them appear as 32 ohms), and 4 lots of 32 ohm speakers in parallel makes a total impedance of 8 ohms. As one of the speaker selector promo says, they “maintain a safe operating load at the amplifier while distributing maximum power throughout your system“. There normally is not by-pass switch on a speaker selector with impedance matching transformers.

Some very budget speaker selector switches have no or minimal impedance protection what-so-ever. They are just a switch turning each speaker on or off. These are not recommended.

For a better understanding of how the different types of speaker selector switches work, see my Speaker Selector Switch Simulators. These show how each type helps with impedance, as well as how they distribute power to each speaker.

The Ins and Outs of a Speaker Selector

A speaker selector is normally known by how many pairs (left and right) of speakers can be connected to it. Each pair of speakers is normally in a different room, or zone. Hence, a speaker selector might be a 4 zone, or a 6 zone speaker switch. Sometimes they are also referred to as 4 way or 6 way. This means they are capable of connecting 4 pairs or 6 pairs of speakers respectively. Be aware some manufacturers also confusingly use the word “channels” for the number of output pairs their speaker switch can connect to.

Some speaker selector switches connect to one stereo amplifier, allowing the speaker selector to connect the one amplifier to each speaker connected to it. This allows the same program (music etc) to be heard in every zone or room.

Other speaker selectors allow two different amplifiers to be connected to them. Then for each zone, you can select amplifier A or amplifier B. These speaker switches are marketed as having A/B inputs. Using two amplifiers with different programs allows each zone to select between the two programs available.

Other Features

Other features often promoted for a speaker selector are:

Volume Controls: These allow the volume of each zone to be separately controlled at the unit.

Power Handling: This states the maximum power (RMS) per channel of the amplifier that should be used with the selector.

Labels: Some manufactures supply pre-printed labels that make your installation look professional.

Speaker Selector Types

There are 4 basic types of speaker selector switches:

Simple Speaker Selector Switches: these simply switch between 2 or more sets of speakers
Speaker Selector Switch with volume control: As well as switching between 2 or more zones, they have separate volume control for each zone
Speaker Selector Switch with A/B amplifier input selection
Speaker Selector Switch with volume controls and A/B selection

How Many Zones?

Speaker selector switches are also categorized by how many zones (or channels of speakers) they can switch.

2 way selectors with impedance protection are useful when the speakers are only 4 ohms, as two sets of 4 ohm speakers is too much load for most amplifiers
4 way selectors are the most popular. These can be used for 2, 3 or 4 zones
5 way, 6 way, 8 way or 10 way speaker selector switches can be used to wire many speakers. With this many speakers, impedance protection is very important

The following tables list most of speaker selector switches available through Amazon. I’ve added as much helpful information as possible including:

the supplier/seller
the model number and/or description of the product
the maximum RMS power (watts) the unit can handle from each channel of the amplifier(s) connected to the selector switch.
the price of each product bought from Amazon (in US$)
a description of the impedance protection method used, warnings and features
a link to download the manual, if I’ve been able to locate one (I like to read the manual before I purchase a product)
a link to each item on Amazon – click on each picture to go to that item on Amazon for further information. If your locality Amazon store doesn’t stock the exact item, the link will take you to a list of similar items which they do stock. Disclosure: If you buy through the Amazon links Geoff receives a small commission from each sale.

Summary of 2 way Speaker Selector Purchases

Disclosure: If you buy through the Amazon links Geoff receives a small commission from each sale.

Item	Watts per Ch.	Price in US$	Comments
Monoprice 8231 2 channel A/B speaker selector with volume	50	$79.99	Designed to use 8 ohm speakers Monoprice Speaker Selector Manual (with volume) Download Manual3433 Downloads
YIS 2 pair speaker selector switch	100	$21.99	Connects both zones in series
Audioflow 2 Way Smart Speaker Switch	300	199.00	Connects both zones in series Designed for use with smart phones
Keen-Eye A/b a B A+b Stereo speaker switcher combiner	10	$16.50	Switch only – no impedance protection Use 8 ohm speakers only
Adwits 2-Channel Speaker Switcher Selector Box	150	$29.99	No information on speaker protection
Tenealay 2-Way Stereo Speaker selector	80	$19.99	Switch only – no impedance protection Use 8 ohm speakers only

Summary of 4 way Speaker Selector Purchases

Item	Watts per Ch.	Price in US$	Comments
Simple Speaker Selector Switches
Monoprice 4 channel Speaker selector	70	$31.21	Uses 5 ohm Series Resistor Monoprice 9995 Manual Download Manual2956 Downloads
Pyle PSS4 4 Channel Switch	100	$44.99	Uses Series Resistor Pyle PSS Manual Download Manual3421 Downloads
Monoprice SS-4 Premium 4 Channel Speaker Selector	100	$49.99	Uses 4 ohm Series Resistor
Niles SS-4 Speaker selector	100	$99.95	Uses 2.5 ohm Series Resistor 72 Labels supplied Niles SS speaker selector Manual Download Manual2435 Downloads
OSD Audio 4 Zone Speaker selector – ISS4	70	$58.84	Uses Series Resistor OSD ISS Speaker Selector Manual Download Manual2407 Downloads
Audioflow 4 Way Smart Speaker Switch	300	$269	Uses series/parallel switching Use only 8 ohm speakers Designed for use with smart phones
Speaker Selector Switches with Volume Controls
Monoprice SSVC-4 4 Channel with Volume Control	100	$99.99	Uses 3 ohm series resistor
OSD Audio 4x Speaker selector with Volume – RSVC4	80	$129.46	Uses Series Resistor
Pyle PSPVC4 4 Zone with volume control	100	$150.99	Minimal impedance protection Use with 8 Ohm speakers Pyle PSPVC Speaker Selector Manual Download Manual3035 Downloads
Niles SSVC-4 4 Channel with volume control	100	204.35	Uses Impedance Matching Transformer Includes 72 labels Niles SSVC Manual Download Manual4729 Downloads
Speaker Selector Switches with A/B Inputs and Volume Controls
Monoprice 4 Channel A/B with Volume	100	$129.99	Designed for 8 ohm speakers
Pyle PSLSW4 4 Channel Selector A/B amplifier	100	$146.99	Minimal Impedance Protection Designed for 8 ohm speakers

Summary of 5+ way Speaker Selector Purchases

Item	Watts per Ch.	Avg. Price	% Sold	Comments	Image (click to view at Amazon)
Simple Speaker Selector Switches
Pyle PSS6 6 Channel Switch	100	$39.29	27%	Uses Series Resistor Pyle PSS Manual Download Manual3421 Downloads
Pyle PSS8 8 Channel Switch	100	$47.70	16%	Uses Series Resistor Pyle PSS8 Speaker Selector Manual Download Manual2085 Downloads
Dayton Audio SS6 Speaker Switch	70	$47.72	2%	Uses 5 ohm Series Resistor	Currently not available
Sima SSW-6 6 zone selector	50	$4124	2%	Uses Series Resistor. Includes lables Sima SSW Speaker Selector Manual Download Manual2465 Downloads
Speaker Selector Switches with Volume Controls
Niles SSVC-6 6 Channel with Volume	100	$239.00	16%	Uses Impedance Matching Transformer. Includes 72 labels Niles SSVC Manual Download Manual4729 Downloads
Theater Solutions TS6DV 6 Zone with volume control	300	$120.99	2%	Has 2 inputs but only able to select one input at a time. No individual input switch for each zone.
Speaker Selector Switches with A/B inputs and Volume Controls
Specialty AV 2 x 5 Zone with A/B & Volume	100	$209.95	9%	Uses high power impedance matching transformer
Monoprice 108230 Speaker Switch	100	$37.58	9%	Uses Series Resistor
Specialty AV 2 x 6 Zone with A/B & Volume	300	$159.95	5%	Uses heavy duty impedance matching transformer
Pyle PSPVC6 6 Channel Speaker Selector	50	$153.99	5%	No Information on impedance protection Pyle PSPVC Speaker Selector Manual Download Manual3035 Downloads
Specialty AV 10 Zone/pair with A/B & volume	500	$259.95	2%	Uses heavy duty impedance matching transformer
Theater Solutions TS6DV Dual Source selector	300	$122.72	2%	No Information on impedance protection Labels Included

Use the above summary information as a guide only. There are also many other models of speaker selector switches available. Additionally, Geoff has written a review of the Audioflow series of switches which are controllable through your smartphone or Alexa.

If you have an install you need further advice on, please read the FAQs before submitting your question. Alternatively, you may find a similar install in the comments below.

Amplifier, Speaker & SPL Calculator

Calculators

Geoff

-

22/03/2014

40

These calculators will find how loud an amplifier and speaker combination will be, or what size amplifier you need to make a speaker a certain loudness.

There are five factors which contribute to how loud a speaker will be:

1) The distance from the speaker. Sound drops off the further you are away from a speaker.

2) The SPL required. This is how loud you want the sound to be at the distance specified. Some general levels are:

70-80dB for speech only
80-95dB for light music
95-110dB for heavy music

3) The speaker sensitivity. This is not an indicator of how sensitive the main (human) speaker is, but rather a measurement of the sensitivity of the loudspeaker. It should be available in the specifications for the loudspeaker (see Understanding Speaker Sensitivity for more info). It is normally stated as the SPL measured 1 metre in front of the speaker with 1 watt of power driving the speaker. Hence the specification will read something like:

Sensitivity (1W/1m) = 85dB

4) Amplifier headroom. This is an allowance for the amplifier to cope with peaks without distortion. At least 3dB headroom is generally recommended. Note that for every 3dB allowance, the power requirement doubles.

5) The power of the amplifier, measured in watts.

In the calculator below, first input the distance from the speaker (and select feet or meters). From this distance the Sound Pressure Level (SPL) loss over that distance is calculated in decibels (dB).

Then, fill in the input fields of either calculator depending on if you want to know the required power for a target SPL (use the first calculator), or if you want to know how loud a given amplifier will be (use the second calculator).

Note: the calculator is best viewed in landscape mode on phones and small screens

Download Calculator
as Excel File

Prices in US$

Note: these calculations are for “open-air” where there are no reflections from walls, ceiling and/or floors. When reflections are present, the SPL losses can be reduced by up to 6dB.

For those who need to know, the formulas used for these calculations are:

$\large{SPL\ loss = {20\times Log_{10}\left(\frac{Distance\, from\, Spkr\left(meters\right)}{1}\right)}$

and

$\large{ Amplifier\ power = \large{10^\frac{required\,amp\,gain}{10}}$

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