Audio switch box build

[wiseoldtech]

Personally I would be nervous of connecting all the grounds of all your connected devices together by clamping the ends of their I/O cables to a metal box. Also, I think I would use twisted pairs for each audio path.

Geoff

My way of doing the grounds is this.......


All in-out jacks - grounded to their appropriate end of the signal board (input ground/output ground.
Case grounding to the main power supply ground.


Almost every device that I've built or modded is done this way and is dead silent.

 

[Tube Radio]

I too normally am nervous about that, but the current switch box has all the grounds connected together I believe and does not switch the grounds that I know of.

 

[wiseoldtech]

I too normally am nervous about that, but the current switch box has all the grounds connected together I believe and does not switch the grounds that I know of.

Since your switch box is a non-powered type, then yes all grounds are tied together.

 

[Tube Radio]

Figured it would be.

Usually with metal boxes I've never had any issues grounding jacks directly to the box as the box usually offers a low enough resistance between jacks to where there's no potential difference at the impedances of the devices connected.

 

[wiseoldtech]

Figured it would be.

Usually with metal boxes I've never had any issues grounding jacks directly to the box as the box usually offers a low enough resistance between jacks to where there's no potential difference at the impedances of the devices connected.

Indeed, metal enclosures ward off external interferences.
My question is is: That DBX200 unit, from the photos I found it's difficult to see, but are those RCA jacks - the outer shells, insulated from the main enclosure?
It appears that way from what I can tell, but they seem to have a typical plastic shrouding holding them in place.
If that's the case, then it is the proper way of mounting, with a central internal ground scheme to eliminate ground loops.
In other words, they are NOT electrially grounded to the enclosure "at the jack shell itself".

 

[Tube Radio]

I think they are isolated, but that switch box uses a PC board which the switches are mounted to and the grounds are ran to that.

 

[wiseoldtech]

I think they are isolated, but that switch box uses a PC board which the switches are mounted to and the grounds are ran to that.

Think is one thing..... knowing is another.


PC mounted jack clusters (plastic) are not directly grounded to the enclosure.
There usually is a central and intelligent grounding scheme on the PC board itself - designed/laid out in a particular way to prevent ground loops.

 

[Tube Radio]

The jacks are the plastic cluster type and solder to the pc board.

I find with grounds, as long as the jacks are mounted to a good solid metal surface for line level stuff with a passive circuit, ground loops aren't really an issue as the signal levels don't have much current.