G5 Power supply Fix for NAP processor cycling noise

[max the mac]

Just a note to let you lot know, I have the latest generation Power supply in My G5 as of today...
With relation to mY MOTU 2408Mk3/PCI424
Seemingly the NAP processor cycling noise (at@ 2.3KHz fundamental) is now completely GONE.
I've checked it with Signal scope, and switching NAP on and off makes No visible difference to the noise floor at maximum resolution.
There is still more 50Hz mains noise than i'd REALLY LIKE... but that too has been reduced
Above 800Hz, the noise floor is now below -130dbV
it ramps up slowly to a nominal -120dbV from 400Hz down to zero.
with Spkies at 50Hz and it's 1st thru 5th harmonic reaching -103dbV Left and -107dbV right .
I'm going to experiment with the mains supply routing and config to see if i can improve on that....
FWIW, the noise floor in my place WITHOUT the G5 switched on is ALL below -130dbV
Which is acceptable....
that said, even with the noise as it is, I now have a dynamic range of @103db
which is tolerable for the moment...I'd like to get beyond 115 though.
The G5's own analogue inputs don't fair so well ( The previous data relates to My 2408MK3)
strangely the noise floor for the Left (Channel 1) Input is up to 30db HIGHER than the right (Channel2) Input.
The noise floor above 3K Left is @-115dbV, and -125dbV Right.
The noisefloor Below 3K rises significantly, at all times in the left channel, but npt the right channel
peaking at -90dbV at @50Hz.... whereas the right channel seems pretty consistent down to @150Hz at -125dbV, peaking at -120dbV at 50Hz.
And here's the kicker for Apple.... NAP processor cycling raises the LEFT channel to an average Hf value circa -100dbV. and 50Hz peak at -80db, but the right channel which seems almost completely unaffected....
meaning they've pretty much resolved the issue for everything but the Left analogue Mac Av channel.
Which of course means that I'm still not 100% happy, but I AM more satisfied than previously.
Out of Ten for the "Fix" effectiveness ... I'd say 6.5/10
to amsys who carried it out...
I'd say 12 out of ten... their service was exemplary and I'll be wanting to continue to use them rather than any other Apple service provider.... Damn good job, quickly , efficiently, and as agreed.... they didn't take the G5 till they already had the parts, and they collected it Tuesday PM, and had it BACK by thrusday Noon ish...
I'm in Oxford, they're In London...
Gobsmackingly more efficient that my Local ASP, or indeed any ASP I've ever used.
I'm STILL going to Push apple to geta total Fix, but for now, anyone with this issue should be able to get it resolved toa workable state.
Figures based on Signal Scope readings.... in FFT mode
Best regards.
Max the mac