Balanced Line Stage - grounding scheme

[Possum]

What is the proper way to implement the grounding scheme for the Balanced Zen Line Stage? So far, I see two options:

1) Using the power supply and preamp PCBs from Kristijan, route the signal and power grounds as it matches on the PCB, and the end result is starish with the star point being the traces of the preamp PCB.

Power supply ground connects to the preamp board. Input signal grounds go from the input jacks through an input switching PCB, through the input potentiometer, then to the preamp board. Output grounds go from the preamp PCB through the output potentiometer, then to the output jacks.

2) A true star scheme ending up at one bolt somewhere in between all PCBs. Power supply ground to the bolt. Input jack grounds to the bolt. Input and output potentiometer grounds to the bolt. Preamp PCB ground to the bolt. Output jack grounds to the bolt.


1 - simple and clean in terms of wiring, but is it less immune to noise?
2 - should the input jacks grounds just go through to the input pot ground? (The same for the output jack ground and output pot ground.) Does twisting a ground line connected from one side with signal lines help at all?

Many of the implementations I've seen in the PassDIY gallery and in this forum tend to go by #1. If there's nothing to worry about with #1, then ignore my thoughts about #2.

Thanks,
Greg

[Taco]

I am using scheme 1 and have no problems, so try the simple version first .

[jh6you]

Originally posted by Possum

2) A true star scheme ending up at one bolt somewhere in between all PCBs. Power supply ground to the bolt. Input jack grounds to the bolt. Input and output potentiometer grounds to the bolt. Preamp PCB ground to the bolt. Output jack grounds to the bolt.

I always prefer 2).
In addition, left-right symmetry from the bolt point of view.

[wuffwaff]

I also used 2). for my X-BOSOZ.
True star earthing will normally make a component more "silent" i.e. darker backgrounds, more details etc.

william

[jarek]

And what about dual mono constructions (two trafos, two psu in one case)?

[Possum]

Thanks for the responses.

If I go with #2, is it necessary to shield the signal lines since they'll be running alone from point to point along the preamplification chain, or is shielding excessive? The longest run of signal wire will probably be about 6-8 inches.

Thanks,
Greg

[wuffwaff]

I use unshielded wire but the longest run is around 4" and all of the transformers are in a seperate box.

william