suggestions for a power supply mod

[neong]

I'll be working on this (not me really, a friend of mine who is aDIYer of itself): Thomann Amp TA2400:



Of course we will put it in a better enclosure (HiFi2000 Pesante Dissipante 3U), change all the cables with better ones (silver/teflon for the signal), substitute or remove all those white ceramic resistors, substitute all the resistors on the signal path with at least Dale 1% or better and remove all the secondary cards (the ones on the output and the ones for the 2 knobs: we will simply put gain at max, without any knob, I'll regulate volume from the pre amp), but most important of all, we will substitute entirely the power supply section:

- We are thinking to use Mundorf M-Lytic HC (which have the best ESR and ESL values of all) in this way:
4 22.000 uF 80 V
2 10.000 uF 80 V
and finally 2 10 uF 800 V Mundorf MCap Supreme

do you have some suggestions for the bypass caps for this section?

- We are also thinking about Silver/Mica on the feedback loop, do you think that teflon tin foil caps, polystyrene caps, paper in oil caps or mylar caps (like the russian PETP) will be better here?

- For the rectifier section we think to follow Nelson Pass idea and so not use Schottky ultra fast diodes: we are thinking about normal diodes, like KBPC, each one with a Wima MKP 10 for filtering, do you think something else would be better?

-For the smoothing circuit we are thinking about Elna Silmic II or Epcos Sikorel LL, do you have different suggestions? And which caps to use for bypassing them?

- Finally we still don't know if this PA is direct coupled or not, in the second case we have to decide coupling caps

[AndrewT]

using a 1.5V battery and a pot, you could apply 100mVdc to the input and measure the effect at the output.

If it is AC coupled it should show no change in output offset.
If it is DC coupled the output should should disconnect due to DC detection and triggering of protection.