Id rather see the RMAA plots you are reporting 1 dB and less changes from and photos of the pulled caps plus re-wiring job. Your source probably also has a DC block and short circuit protection resistor, My pre-amp also has "lab outputs" which are the normal one w/o the DC block.
Id retake the RMAA plots with the source PC in loopback mode rather than using the 2nd one.. Id expect changes for the better. e.g. less common mode noise.
Id say your eyes maybe just as good as your hearing. e.g picking out 1dB resolution on RMAA plots. If (from your posts) you are relying on the software to give a number then I'd question any reported changes due to repeatability of the experiment as null -n-void.
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What makes you think that. I see the base currents cancelling and the left over is supplied through a small output resistor biased at 0V.
Meant it more in general.
Thanks, I'll make sure to test how low frequency dynamics are affected next time I use such rails filtering. I suppose it would be relatively easy to visualize this on a scope with a realistic load? Or would you advise some other method?
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If the OP is not imagining the differences, then it seems to me there is something going on with real music which is not revealed by measuring with sine waves?
It's tempting to suggest putting it back to standard and building from scratch.
See the LM317 thread and ask yourself about the effects of 2 470uF on each reg output.
It makes me wonder what the rails look like in actual use.
Maybe it needs to be tested in different ways to see the effects of the mods.Maybe think in the time domain. Throw some arbitrary wave forms at each channel and see what it does?
It's tempting to suggest putting it back to standard and building from scratch.
See the LM317 thread and ask yourself about the effects of 2 470uF on each reg output.
It makes me wonder what the rails look like in actual use.
Maybe it needs to be tested in different ways to see the effects of the mods.Maybe think in the time domain. Throw some arbitrary wave forms at each channel and see what it does?
I would prefer to do it in simulation (I use LTspice) as then you're not limited by your scope's capabilities and you can quickly explore various options. I'd recommend LC filtering, rather than RC but watch out for getting the damping right.
I don't know how to correlate yet what I see in sim with what I hear but I do my best to minimize supply ripple, most especially signal-correlated ripple.
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