AMB Laboratories DIY Audio

[Heffa]

I have yet another earth/grounding question regarding the sigma11. I've tried to find an answer in other threads, but so far no success.

My sigma11 have the transformer in a separate chassis, and am planning to use this to drive my upcoming PPA headphone amp.
Here is the setup:

transformer in metal enclosure, earth is connected to the chassis, and 24V AC + earth is forwarded to the actual:

sigma11 in metal enclosure. The chassis is connected to earth as well, through the connection from the transformer box. From here I have 4 x 24V DC output connectors, and one of them is supposed to power the:

PPA headphone amp, driven by 24V DC from the sigma11. Chassis not connected to earth.

Note that the only part that is actually completed so far is the sigma11 box, but here my problem arises; the DC connectors I have used are NOT shielded from the chassis. That means that V- is connected to earth, wich I supposed is not good
I know that I should have checked this BEFORE building the sigma11, or at least before I drilled out the panel and everything, but what is done is unfortunately done.

Is there anything I can do, short of replacing my connectors to something else?
Could a ground loop breaker be used in some way, or am I basically lost?
Would it be a bad idea to disconnect earth from the sigma11 box altogether? I really dont like that idea, but perhaps that would be acceptable since there is no 230V there?

The power jacks I am using is Switchcraft L712AS

Regards,
Hakan

[amb]

If I understand you correctly, you have a 3-enclosure build, the transformer in a separate enclosure from the σ11, and then a 3rd enclosure for the PPA. If so, the transformer enclosure should have its chassis connected to AC earth (as you described), but the σ11 chassis does not need to be connected to any earth or ground at all. You should also use an isolated DC jack so that the chassis isn't tied to V-. The PPA chassis can be connected to its IG, and if there is a DC jack there, it should be isolated too.

A ground loop breaker is not going to do anything for you here.

[Heffa]

Thanks for the reply!

I was afraid that is would be like that, it means I have to get some other DC jacks, and somehow build a new panel för the sigma11

[amb]

You might be able to use the same DC jack (depending on its design) by mounting it to the panel with some kind of isolating washer. Or, mount it to a non-conductive material (acrylic?), and then mount that to the panel (after enlarging the hole).

[Heffa]

Yes, I was thinking of trying out a piece of heat shrink tubing or similar.
That might work since the connection is made where the jack goes through the panel.