What is better sounding I/V con. ?

[Gasho]

I will measure the "1M" resistor , I don´t think this is true feedback loop. On PCM 63 , pin 6 i current out , an pin 5 is offset

 

[Franz G]

Do you have a source for PMD100?

Yes, I have, but just for one piece

I still try to get it out of this burned DAC board, out of a Classé DAC-1.

I will use the dremel, as I cannot unsolder it (litz wire and pump dont work) up to now...

Hopefully, it is still working! And I will use secondary fuses for every voltage supply!!!

Franz

 

[Franz G]

I will measure the "1M" resistor

Looking a second time at the circuit: 1M will be O.K., as this is a parallel circuit to R307 (3.3K) and lowering the value just a little bit to achieve the wished higher gain for CD reproduction.

But one question still remains: what is the purpose of the caps C301/C331 in the feedback path using CD-mode?

Franz

 

[Franz G]

I looked a third time at the circuit and redrawed the essential part to understand it better.

For the gain calculation, it seems essential to look at the following stages, as the feedback is included in the first opamps circuit.

Franz

 

[Franz G]

Finally, I managed to get the PMD100 out of its original board:

It was no fun, this work, because I could not remove the solder in the through contacted board

Franz

 

[hcosborne]

What I/V conversion on BB PCM63K gives more natural , and transparent sound .

Active (AD847) , or passive with high quality , precision resistor (100ohm) connected from current output of DAC to ground?

I am currently using a 10 ohms precision resistor on the current output of my PCM63K. The signal is fed into an instrumentation amplifier followed by an open loop buffer. The sound is quite good.