Re: Re: Trying to understand circuit
Hi Koifarm
Thans for your detailed reply.
Koifarm said:
The output you can take from anode V1 (a1) or from kathode V2 (k2) that is the difference.
Thanks. That solves the puzzle for me. Obviously, I still need to read a lot about theory.

I have built output stage based on Lukasz circuit, based on 6n1p. Now I know how to calculate the out impedance properly, as I am taking output from k2.
The music becomes so much real & involving, after doing this mod, replacing the discrete stage previously. The digital sound is getting closer & closer to my EMT930, which I couldnt have imagined few months ago.
Recently, I installed Lundahl 7905 interstage transformers. Now my resistor is 22 ohms, giving 25 mV with 1 KHz tone, hopefully? staying within Phillips recommended 25mV for TDA1541A S1 to prevent distortion. The jump in quality was again very big. The bass is deeper & tighter, mids even more analog like. Even my 10 yr old preferred it each time in a double blind test & commented on the bass & 'live' like quality.
Koifarm said:
With the SRPP it is important that you now the input impedance of the amplifier you connect to. This must be the same you calculate the SRPP for. If not there will be more distorsion as wanted.
If your amp has a higher input impedance you can simple lower the impedance by parallel a resistor to match the SRPP stage.
Unfortunately, I have been unable to find the input impedance of my tube technology HB70 amplifier from manufacturer & dont know any other to find out. Now my calculated dac output stage impedance is 2.2 K. What will be recommended amp input impedance? I presently have 250K resistor in parellel after tube stage.
Best regards
Fib