Sanity check: input grounding scheme

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Rundmaus

Rundmaus

Member
Joined 2005
Hey there,

is this a sensible grounding scheme for an amplifier input selector and volume control?

grounding.png


Note that red means signal, blue is ground and the dotted black lines indicate runs of coaxial wiring...

Obviously, the wiring as shown will lead to ground loops if the source does not separate L and R signal ground. Is this a problem and are there better ideas from your side?

What is the 'diyAudio best practice' for this part of a circuit?

Regards,
Rundmaus
 
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AndrewT

R.I.P.
Joined 2004
Yes, it is absolutely important to keep the Signal Flow alongside the Signal Return from each Source to each Receiver and as DF says, keep the loop area small.
The "switch" becomes the Source for the next inter module link and each half of the vol pot becomes the Source for the next link.
Think about a Buffer after the vol pot if your cables are to be anything longer than 1m.
 
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AndrewT

R.I.P.
Joined 2004
If the sources have a commoned Signal Return, then when your two cables arrive at your Stereo Power Amplifier you will have a big and unavaoidable loop in your signal returns.

Read D.Joffe and his HBRR+HBRL solution to attenuating the interference voltage in your signal wiring.
 
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tansand

Member
Joined 2016
Good information, AndrewT, thank you. It seems to me that using balanced connections would work too?...but I don't know that much about electronics. I've been thinking about this because if you put a passive volume control in a metal case, apparently you have to connect the returns unless you leave the case floating. Or use monoblocks :).

I was also thinking of only connecting one return to the case, without connecting it to the other return. I don't know.
 
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tansand

Member
Joined 2016
Yes, I think. I was thinking of having two complete, seperate channels, with isolated jacks on both sides, and attaching one of the channel's return to the metal chassis, but leaving the other channel unconnected to either the chassis or the other channel. Like I said, I don't know, it sounds a little flaky, but it's just the 'shield' of one of the interconnects extending to cover both channels...
 
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