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Speaker switches – what you need to know
Some amplifiers have switches on the front to select speakers A or B or A and B. If not, you will need a speaker selector switch.
As well as switching the speakers on or off, the selector switches have some extra parts inside to ensure the amplifier is not overloaded.
You can get switches designed for 4 or 8 Ohm amplifier outputs. They make sure the load as seen by the amplifier does not drop below 4 or 8 Ohms respectively.
Your switch information might say “load no greater than 4 Ohms with speakers of 4 Ohms or above”. This means that so long as each speaker used is 4 or 6 or 8 Ohms, you won’t have a problem.
On the back of your amplifier, the output rating should be visible. For instance it might say 50 Watts RMS per channel at 4 Ohms. For this case, choose a 4 Ohm switch. Make sure the RMS rating for the switch you’re thinking of is suitable for the amplifier. Your amplifier should have protection inbuilt. Your speakers should also have a loading or impedance value displayed on the back of them which might say 8 Ohms, for instance.
Next you need to decide how many outputs you require. You can get 2, 4 or 8 channel units readily. The way you wire the unit is to connect the outputs of the amplifier (left and right) to the input of the switch. Next, connect your existing speakers to output 1 and your new speakers to outputs 2, 3 etc. as stereo pairs.
Now, as you select any combination of your speakers, you can rest assured that you won’t be damaging your amplifier.
Another variation of the speaker switch has volume controls associated with each output along with the basic switches discussed above. With these you can adjust the volume in each area independently. Of course they are more expensive as there is some power to control and heat to dissipate but they are a way to get a reasonably priced system that will provide sound around the home.
You won’t be able to turn things up as you could with just two speakers as the volume controls have a rating which shouldn’t be exceeded but if you don’t require your music loud, these could be suitable.
The third version of the speaker selector switches has two sets of amplifier inputs. Here you can use to amplifiers and have each amp playing different music. On the selector switch, for each output, you can choose ‘off’ or either amp A or Amp B and then control the output level of each. Once you’ve set up the relative levels of each output using the output level controls to your requirements (perhaps quieter in small rooms, louder in larger rooms), as you turn up the main amplifier all outputs will rise in level together.
The wiring for all of the switch types is normally connected via rear panel terminal blocks. There are units with 4mm Banana Plug connections for those that prefer them.
There will always be less output volume available than was put in, due to internal losses within the switch and volume controls but if this is not considered a problem, a versatile system can be realised for little cost compared to the home automation solutions
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Digitech RP1000 Effects and Amp Switching System