Grounding... again.

[Sammas]

How would one ground a console, an equipment rack and computer in a simple home studio without a dedicated mains circuits?

The console has a seperate audio ground from the ground for the power supply. The power supply is sitting in the bottom of the equipment rack with outboard and audio interfaces in the top. The outboard and interfaces are wired to the console via balanced tielines that are only grounded at the source end.

Could I connect the console's audio ground to the rack rails, with everything in the rack including the console's PSU plugged into a power conditioner (mounted in the rack) then only plug the power conditioner into the mains outlet?

 

[Svart]

Dufas

Is that a technical term?

:green:

 

[amorris]

technically its "Dufus"

 

[SSLtech]

Dufus.

Dufi. (Plural)

Keef

 

[Sammas]

[quote author="mediatechnology"]Sammas: It sounds like from your description that everything is being powered from one (AC) circuit. I'm not sure that taking the console's audio ground back to the rack rails will do much: Everything is meeting there already and unless the console's PSU has an isolated ground the reference will be at the PSU case and rails. I doubt it would hurt.[/quote]


Excellent! You are right, I was under the strange impression that the ground lug and PSU ground were independent of each other. I plugged a single module in (in the process of cleaning them now), then "buzzz"... Continuity between the ground lug and PSU case. Go figure, leaving the simplest thing til last

Although you may not see it this way you essentially have a dedicated circuit by virtue of the fact it's powered from the one circuit. (Unless of course other stuff is also on that branch which may or may not be problematic.)

Is there a hum problem now?

It has only been powered up to test the master modules and a few channels just using a CD player as the sound source. Crystal clear and dead quiet.

If you start adding studio devices that are plugged into other circuits, or the same one at a different outlet, there may be loop formation. Being in a home on a 120-0-120 system and powered from just one outlet you are very fortunate. Be aware of other loads in the house also fed from that breaker though.

One thing you could do is have an electrician re-torque the outlet screws, open up the main panel, and retorque the breaker, neutral and ground buss screws. On even a home of modest age I rarely find them tight: They just back out or the copper compresses.

If a DIY electrician from a previous owner has been set loose in the house look for swapped neutrals and grounds. I had a huge hum problem with a circuit on another breaker. Even turning on an undimmed overhead light would produce hum. Turns out the Dufas who re-wired had swapped neutral and ground at the fixture. The load was returning through ground. He did this in about three places that I've found so far.

The mains circuit is only a few months old (courtesy of a mate who is a sparky by trade). The room is actually an old workshop. The lights are on the same circuit breaker for the rest of the lighting in the house. The new mains circuit comes straight from the fuse box with its own dedicated circuit breaker. The other items on that breaker will be whatever else is plugged into the four outlets in the room... maybe a desk lamp or something similar. If there are any problems, its isn't terribly hard to lure the sparky back with beer :green:

Adding a second rack should be a piece of cake then, just keep the same grounded at the source end only scheme and plug that rack into its own outlet.

Thanks a lot! I appreciate it :thumb:

 

[Sammas]

[quote author="mediatechnology"]Sammas: You're welcome. Where are you? Are you in a 120 v world or 240? I ask because you used the term sparky. Just assumed you were in the US.

Be advised that the "noise gain" (and hum too) of the console will build up as you add modules.

Sounds like you're in good shape though...[/quote]


I am in Australia, 240v world. :wink: