Speaker on/off switch: locate in Line-level or Speaker-level path?

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I have a 4-channel Sure TK2050 amp board that I'm using on my back deck. Two speakers face the yard and two are near the hot tub. I'd like to install an on/off switch for each set of speakers so I just use the ones I need at any given time. Are there any advantages or disadvantages to consider whether I cut the signal before or after the amp?

Thanks!
 
Before the amp is where you want any switch. After the amp, you would be trying to switch higher power. Also, many amps don't like running with an input signal but no load connected.

Does your four-channel amp board have four inputs? Or two? Or one?

If it's one pair of stereo inputs, then how could you switch them so that only one set of speakers was on? You would instead want to "mute" one set of speakers (two of your channels), in that case. If the amps don't have a mute function, you might need to insert switch leads into each pair's input circuits. That would be a little more complicated, but maybe not too bad.

Either way, you should probably consider using a multi-pole double-throw (on-on) type of switch, so that the signal input gets connected to ground, when the switch turns off that input, instead of leaving it floating (connected to nothing).

If you wanted to be able to switch one stereo pair off and on, you could use a two-pole two-throw (2P2T or DPDT) switch (one pole for "left" and one pole for "right"; basically two switches in one) and attach the two incoming (left and right) signal "+" lines to the two "common" pole connections of the switch, and connect the two switch positions' connections for each pole to 1) the input "+" that continues to the amp input's + connection (for "ON") and 2) through a 10k resistor and then to input ground or "-" (for "OFF").
 
Thanks for the reply! This amp actually has four independent inputs, one for each channel. I initially thought I'd just split my two-channel source-signal into four and have two DPST switches, (one for each stereo pair). I'm not sure I followed your advice on the grounding or adding the resistor. I'll have to re-read that a few times :)

Here is a schematic for the amp:
http://www.parts-express.com/pdf/320-302m.pdf

I looks like there is a mute pin on the chip but I don't see any way to independently control the channels this way.

What do you think is my best course here? Can you please explain the last paragraph in different terms, I got a little lost on how that would work. Thanks!
 
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