[sek@]

Precision mill, my ‰¶¿
I usually just cut a V-groove with a blade.
 
So it was a loop of return currents, presumably between top and bottom layer (via plated through holes)?

 

[wakibaki]

I think it's most useful to think of it in terms of how you would ground it if it were point-to-point wiring.
 
You might bring the quiet grounds such as the feedback to the input or output jack (which would be joined) and return the decoupling caps up to the regulators which would form a star for the PSU.
 
As it was, current from the caps down the LHS of the board could migrate diagonally from close to the input jack up to the regulators, polluting the signal areas in the process. Cutting the 2 ground planes forces the PSU return current to flow in a clockwise direction into the area above the regulators and separates the noisy PSU area from the signal area.
 
I think.
 
I've always found grounding a difficult issue, particularly in PCBs with a ground plane, but although I've generally taken care I think I've been lucky with the results, which led me to be a bit casual in this case.
 
Anyway, whatever the reasons, the cuts make a huge difference, I can't tell by listening whether the amp is turned on or off regardless of volume setting.
 
Please let me know when the boards arrive, they're all marked 'no intrinsic value' so there should be no holdup at customs.
 

Originally Posted by G.Trenchev /img/forum/go_quote.gif
 
wakibaki,could you post results at 16/44.1 or 24/44.1 ?I want to compare my amp to yours.

 
Here are the results @ 24/44k1 showing the soundcard alone and soundcard + amp. Edited to include results for 16 ohm load.
 

 
w

 

[shadow419]

Quote:

Thanks Sebastian, I was beginning to feel that I was talking to myself. Odd that there's so little apparent interest, this is potentially a very high-performance design at a very reasonable cost.
 
.....snip

 
I'm sure they're a lot more people lurking, like myself.  

 

[Avro_Arrow]

If there are people lurking that are interested in the project, they should make themselves known, like you did.
The more people that show interest, the more effort a designer is likely to put into a project.
 
Quote:

 
I'm sure they're a lot more people lurking, like myself.  

 

[wakibaki]

Quote:

 
I'm sure they're a lot more people lurking, like myself.  

 
Good. Come out, come out, wherever you are...
 
I just took delivery of a new USB oscilloscope, so I've been playing with that...
 
Output RMS voltage 1kHz test tone (Hantec DSO2150 USB scope):-
 
Unloaded 317mV 
 
Loaded 309mV
 
Load 16 ohms
 
Output impedance (calculated) 0.41 ohms
 
w
 
I see a newer version of RMAA (6.2.4) has been available since 02 April 2012. Good, there may be some improvements coming.

 

[J-Pak]

I'm interested as well
 
Does it accept balanced input only?

 

[Avro_Arrow]

The amp is single ended, not balanced
 
Quote:

I'm interested as well
 
Does it accept balanced input only?

 

[J-Pak]

Quote:

The amp is single ended, not balanced
 

 
Even better, my source is S/E

 

[shadow419]

Quote:

If there are people lurking that are interested in the project, they should make themselves known, like you did.
The more people that show interest, the more effort a designer is likely to put into a project.
 

Probably should have chimed in sooner, but my knowledge of circuits is very limited.  Didn't want to post just for the sake of posting without any contribution to the discussion.  I do enjoy tackling diy designs though if  for nothing else than the satisfaction of completing something.

 

[Nebby]

Count me as interested

 

[2000impreza]

I'm very interested as well. Missed out on "the wire" awhile back.

 

[sek@]

Just as a quick update: board arrived fine. Thanks very much.

 

[tyre]

I'm also interested, but quietly lurking as the discussion is largely over my head.

 

[Avro_Arrow]

@ wakibaki
 
You officially have a following...

 

[Avro_Arrow]

Got my board today...Thank you!