Switching Out between two Ins: trying to prevent amps from buzzing when not connected to Output

Stereo line-level DIY audio switch, trying to block the buzz when not connected.

Recommended values R1-R4? I imagine not too low as to noticeably load the Output, yet low enough to cut the interference (the amps are buzzing when inputs are not connected.)

Is this even the best way to prevent the buzz/interference?

Thanks.


Switching betw 2 audio inputs Line-Level Analog 20230904.jpg
 
Something like 10k to 22k is reasonable - you are adding loading to the source this way, but too high a resistance could lead to audible white noise and the mains pickup you wish to avoid.

Having a separate DPDT switch for each amplifier that switches the amp's input between the DAC and ground would both finesse the problem, and allow both or neither modes of operation too.
 
How about use the DPDT switch only on one amp inputs
True, but I'm afraid the unused (whichever) line still connected to the audio bus may introduce unwanted effects. Say, I unplug RCAs on headphone and the short on something metal...
But if I switch that input off physically, this should not be a problem, methink...
And from that paranoid viewpoint, I guess 8PDT switch would be best - to connect/disconnect both line and ground of the unused amp from the Out bus...
A friend even suggested something like CD4052BE...
 
I start thinking that, to be 100% on the safe side (including any static electricity disturbances from the unused amp and its cables), I probably should be switching both signal and ground on each L/R channel, on each amp. So 4 contacts per amp, 8 total...
 
Static electricity doesn't come from electronic equipment, it comes from insulators + friction. There is something to be said in favour of isolating the grounds too, but for ground-loop-breaking reasons rather than "static".

If you do break grounds you have to worry about the order the connections are broken/remade - if the signal connects before the ground you'll get a voltage spike, potentially large, which might not be what you want.
 
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While switching the amp's input, I'm getting huge POPS in the speakers. On both connect and disconnect.
The switching is done with a simple mechanical electric switch. LR inputs are shorted to each other and their ground. On Connect, they are connected to the preamp Outs.
What can I do to prevent this popping? Not only is it super unpleasant, but also seems dangerous to both electronics and the speakers :|
 
...If you do break grounds you have to worry...
So I finally solved the loud POP mystery in my switch. Tried to exclude DC, used other approaches, but nothing helped - the huge click occurred every time I'd switch the source.

Well. It was because I was breaking Ground.

If Ground is not interrupted, then there's no pop! (And I also cannot detect any interference from another line's Ground still being connected, so apparently my concerns were unfounded. I was solving a non-existing problem, and in the process created a real one for myself. In another thread people were saying no known audio equipment switches the ground, only signal ¯\(ツ)/¯ )

Thanks much to everyone who contributed!
 
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