Speaker Selector Switch Simulators

The speaker selector switch simulators presented here demonstrate how speaker selectors deal with speaker impedance and power distribution. Speaker selector switches are used to allow you to connect multiple speakers to your HiFi amplifier. They help to keep the total impedance safe for your amplifier. How do they do this? How do the different types work? How do they divide the power among the speakers? Read on…

These speaker selector switch simulators are ideal if you:

  • are thinking of buying a speaker selector switch and want to know the best type.
  • want to know how to use them better
  • would like to know the effect on impedance and speaker power with different settings.
  • like to know how speaker selector switches work

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.

How to use the Speaker Selector Switch Simulators

Speaker selector switch simulators schematicThe speaker selector switch simulators below are based one a setup similar to this diagram. Only one channel of the amplifier is shown as speaker selector switches (and the simulators) treat both the left and right channels the same.

Basically you need to fill in the white boxes.

Start by typing in (or select from the drop down list) the rated impedance of each speaker pair connected to the speaker selector switch. If you are using less than 6 speakers, simply select “no speaker” in the drop down list for the unused speakers. You can also make each speaker selector switch simulator act like a 2 way or 4 way speaker selector by using “no speaker” for the unused channels.

The on/off switches under each speaker simulate the on/off switch for each speaker zone on the speaker selector. As you turn each switch on or off the total load impedance and the power through each speaker is re-calculated. Depending on which type of simulator you are using, you may also need to type in the series resistor value or the volume control settings.

Then the amplifier section, select the minimum impedance your amplifier is designed for. Then type in the maximum RMS power your amplifier will produce at this impedance. This information is normally found in the “specification” of your amplifier user’s manual.

Speaker Selector Switch Simulators

There are three main types of Speaker Selector Switches. There is a simulator for each type.  You can use the buttons as a shortcut to each type.

Series-Parallel Type Simulator Series Resistor Type Simulator Transformer Type Simulator

Series-Parallel type Speaker Selector Switch

How they work: Series-Parallel type of speaker selector switches use switches to connect the speakers in a combination of series and parallel. Speakers 1 and 2 are connected in series, as are speakers 3 and 4.  Then each series pair are connected in parallel.

Pros and Cons: There is no power lost due to the switch.  They are not expensive. Can be used for 2-4 speakers. Do not work for all speaker/amplifier combinations. Normally recommended for 8 ohm speakers. If using three speakers, don’t turn the spare (4th) zone on, or it will disconnect the 3rd speaker (because there is nothing to be in series with).


Series-Parallel Type Simulator Series Resistor Type Simulator Transformer Type Simulator

Series Resistor type Speaker Selector Switch

How they work: When the “protection” switch is on, a resistor is placed in series with the speakers. The minimum load impedance will not go below the value of this resistor. Turning the “protection” switch off removes the resistor from the circuit.

Common resistor values used by different manufactures:
2.5 ohms: Niles
3 ohms: Sima
5 ohms: AVX, Monoprice, Parts Express

Pros and Cons: While the resistor takes care of the total impedance, it can also take a lot of the power. Therefore the resistors can get quite hot. Normally not recommend for higher powered amplifiers. The lower the resistor value, the less power loss through the resistor, but the less impedance protection offered.


Series-Parallel Type Simulator Series Resistor Type Simulator Transformer Type Simulator

Impedance Matching Transformer type Speaker Selector Switch

How they work:  Each channel has a transformer which effectively multiplies the impedance seen by the amplifier. For example if the multiplier is set to x2, a 4 ohm speaker will appear to be 8 ohms. The trade off for this is that the power available to the speaker is divided by the same factor.  Most transformer type of speaker selector switchers have a switch at the rear to set the multiplier to x1, x2, x4 or x8. In practice transformers are around 90% efficient – this simulator is based on 90% efficiency.  Most impedance matching transformer based switches also incorporate a separate 12 step volume control for each channel. This simulator also allows for different volume control settings.

Pros and Cons: Can be used for most speaker/amplifier combinations. Are more efficient than series resistor type, and do not normally get hot. Can be designed for higher powered amplifiers. Provide individual volume control for each zone. Are generally more expensive.



If you need to buy a Speaker Selector Switch, here is a link to the range at Amazon (Note: if you purchase anything from Amazon (US, UK or Canada) I get a small commission – thanks for the support)

How much power do I need?

The above speaker selector switch simulators may surprise you regarding how little power can reach the speaker when you have multiple speakers connected to your Hifi amplifier. Don’t get too stressed. People have been using these switches for many years with no problems. What these simulators show is that you don’t need a lot of power to fill a room with sound, especially for background music.

The loudness of your speakers will also be determined by the speaker’s sensitivity. If you would like to explore more about how much power you need for each room in your house, you can use my Amplifier, Speaker and SPL Calculator

Other articles you may find useful:

If you have question on installing a speaker selector switch, please read the FAQs before submitting your question. You may also find an answer is the comments below.


  1. Hi Geoff,

    I was looking for a speaker switch (via Google) and came across your website. 🙂

    I need a switch for my outdoor Holiday displays.  I have a single speaker behind each of my yard displays:  Charlie Brown, Nutcracker, and Sam the Snowman.  Instead of manually changing the wires each night (to a different display), I would like a switch box that will allow me to change the music from indoors.  Do you have a recommendation for this type of (unusual) set-up?  [It’s ok if it is monotone, and an in-line (speaker wire) style.]

    I look forward to hearing from you.

    Thank you. 


    • Hi Dan,

      If I understand your situation correctly, it seems all you need is a simple 4 way speaker selector switch. Just use the one channel, (say the the left) for the input and the outputs. Then simply select the output zone (speaker) you want for each night.

      You will not need to use the protection switch, as you are only using one speaker at a time – not multiple at the same time.

      hope this helps


  2. Geoff,
    Thanks for such a well done site.
    I am considering a Monoprice 4-Channel A/B Speaker Selector w/ Volume Control
    Product # 8232. My question is when used in a higher quality hi fi system such as my Bryston amp and pre amp will I see any reduction in sound quality using this type of selector especially one with volume controls?
    Thanks again,

    • Hi Brad,

      That is a good question.

      Unfortunately Monoprice (like a number of others) are fairly short on technical details. Their “manual” doesn’t explain how it keeps the total impedance above 8 ohms. It does say it is good for 20Hz to 20,000Hz, but with no criteria as to how flat that is.

      From the price and the vent holes in the side, I suggest it uses a series resistor to keep the impedance higher than 8 ohms. I suspect (but have no evidence) that it uses resistors for the volume controls too – rather than the more expensive transformers.

      Now I suggest resistors don’t inherently alter the sound, just reduce it. However I would have thought that a series resistor would have considerable effect on the damping factor. This would make the bass frequencies (below 150Hz) less tight. For most installs where speaker selector switches are used for background music systems, this would not be noticeable. However if you enjoy the benefits of very tight bass and have the time to stop and listen to it, then it might be noticeable to you.

      Sorry I can’t give you a more definitive answer, but I have insufficient facts to make an objective argument.


    • Thanks very much for your insights Geoff,
      I have ordered the Monoprice unit with volume and suspect it will fill my need quite well.

      Kindest regards,

  3. Hi Geoff. Much respect for the quality and detail of all of these articles.
    I have a question from the budget end of the hifi world.
    I have a record player hifi system that lists it’s specifications as follows:
    – speaker max output/ohms : 5W / 4 ohms
    – speakers : 2 x 2W

    I aim to connect two pairs of speakers, one pair for a small dining room and one for a small kitchen. I usually listen with the volume set at 50% and would not go above 80%.

    I have two spare sets of speakers, a 4 ohm pair and an 8 ohm pair, and I have purchased a series/parallel 2 zone selector switch that describes itself as providing a safe 4-16 ohm load range, up to 200W rms per channel.

    Would you recommend using the spare 4 ohm speakers or the 8 ohm speakers? And would there be any risk of damaging the hifi amplifier if both zones were switched on at the same time?

    Your speaker selector simulator suggests that it would be okay but I just wanted to check.

    Many thanks in advance,

    • Hi Dave,

      Either of your extra set of speakers will work through the switch. It might be best to try them and see if one of them sounds better than the other to you. Whichever you use, the switch will make it safe for the amp.

      In theory the 4 ohm pair will allow both sets to sound a bit louder than the 8 ohms pair when both are on, but you may not hear that much of a difference.

      hope this helps


  4. Hi Geoff! Great website, thanks for all you do. Quick question and I’m not sure if I’m understanding this correctly. I’m using one of your calculators and have come up with this situation. If I’m using a impedance matched transformer speaker selector with volume control, the general trend is that as I lower the volume of one speaker pair, it adds impedance to that one pair (as expected). A by product of doing so, increases the amplifier power to the other speaker pairs. Would it be a correct assumption to think the other speaker pairs would increase in volume (due to the increase in power) as another different pair was lowered in volume?

    I hope I’m explaning this correctly and can elaborate if needed! Thank you again.

    • Hi Dane,

      I’m glad you find the website useful.

      You are correct, as you turn one speaker down (or off), the power available to the other speakers will increase, in theory. In practice, the difference will be a fraction of a decibel, and not really perceivable. Also, as you increase the total load impedance on the amp, this will lower the maximum power output of the amp. So again, you won’t really hear any difference in the other speakers as you adjust one.

      hope this helps


  5. Hi, Geoff.
    Thanks for all the great switch simulators. I have a question about the series type switch. How is the power loss through the switch calculated. I tried to calculate it using Ohms’s law but am having trouble. How do we know what the voltage is at a particular load? We have the power at 4ohms, (80watts), and can therefore solve for voltage at that load, which is 17.89V. Do you use that same voltage for all the calculations? For example, 3 speakers in parallel with the 5ohm resistor in series give a total resistance of 7.67 ohms and the current would be 2.33amps according to ohms law I=V/R using 17.89V and 7.67 ohms . Therefore, P=V x I gives a power of 41.68watts and a loss of 38.3watts from the original 80watts. However, the simulator shows each speaker getting 9.3watts for a total of 27.9watts and a loss of 52.2watts. What am I missing? I also noticed in the simulator, if you have only one speaker at 8ohms and the 5ohm resistor engaged you get 49.2 watts to the speaker, but if you drop the speaker down to 4ohms you only get 35.6 watts. Seems counterintuitive. I would think at 8 ohms your would get less power than 4 ohms. Sorry, if this may be to complicated to explain here, but I am just curious am trying to exercise my brain with the calculations. Thanks.

    • Hi Don,

      The secret to your first question is that the voltage and current changes every time the total resistance changes. So your calcs are correct for 4 ohms, but when using a load impedance of 7.67 ohms, the total current will not be 2.33 amps but 3.23 amps (sqroot(80/7.67)) and the voltage will be 24.78 volts. Using 3.23 as the current, the power through the 5 ohms resistor will be 55.2 watts. Your calcs are correct, but you need to recalculate the current and voltage every time the load changes.

      In regard to the series connection, you are right, it is counter-intuitive. We are so used to thinking of speakers in parallel where the lower resistor takes more power, that the series connection plays with our minds. We need to think logically. As the power through a resistor is current(squared) x resistance, as the resistor value increases, so will the power.

      Thanks for making my brain sore by having to think through all this again:)

      hope this helps


  6. Hello Geoff,

    First off, thank you so much for posting this information. It’s been incredibly helpful, I’ve learned a lot. I’m putting together a multi-room system for my house. My plan is to have my Onkyo TX-NR656 drive the whole thing. The front A output will have 6ohm Elac speakers, the assignable B output will go to a Niles HPS-4 speaker selector. I will only have 3 pairs of speakers coming out of it. I’d like another pair of 6ohm Elac speakers then have 2 pairs of 8ohm speakers. I’d like In-line volume controls to the additional 3 sets of speakers. I’m fairly certain I will get decent sound of out of this set up, my real question is, will I damage any of the equipment? Any information would be greatly appreciated!!

    Thank you!!!


    • Hi Michael,

      I’m pleased you have found the site useful.

      It looks like you have it all sorted. I assume you mean “zone 2” when you talk about the B output. If that is the case, then you should be fine as zone 2 outputs are 2 separate amplifiers. The speaker selector you mention should be fine. While using it, you can use volume controls without impedance protection as the speaker switch will look after that you.

      Have fun with it,


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