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
The 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
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 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.
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 USA via this link Geoff gets 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.