Don't forget to change R19 from 100R to 330R too. C2 was increased to 220pF in 3.5x (11dB) to get better Phase margin in CFA mode, but you can try with 100pF, phase margin is still good at 68 degree. It does not influence non GNFB mode to much.
By the way what kind of volume potentiometer you use? With the best quality as ELMA stepped attenuator you can get much more from this preamp.
Last edited:
Here we are.
During my latest listening session with a ZYX bloom cart and a Nagra pyramid poweramp, I noticed some sibilance.... probably due to cart misalignment.... this preamp is ruthless.
But the soundstage was huge and the transients really fast.... will need to replace the rectifying diodes and the volume pots.
No hum, no hiss... perfectly silent in operation.
During my latest listening session with a ZYX bloom cart and a Nagra pyramid poweramp, I noticed some sibilance.... probably due to cart misalignment.... this preamp is ruthless.
But the soundstage was huge and the transients really fast.... will need to replace the rectifying diodes and the volume pots.
No hum, no hiss... perfectly silent in operation.
Attachments
It looks good. Why do you want to replace rectifying diodes?
By the way you have some good equipment there.
I am quite well connected so I am able to listen with some very interesting electronics.
The rectifying diodes have a major role in SQ principally using this type of shunts (I built more than 20 variations on this theme).
Rectifying diodes, smoothing caps and the TX themselves are quite important when using these marvellous shunts.
Instead of using a zobel between the TX and the diode bridge I always found that using HEXFREDS provide the best results. The major differences are in the treble and it is there that this preamp excels.
The rectifying diodes have a major role in SQ principally using this type of shunts (I built more than 20 variations on this theme).
Rectifying diodes, smoothing caps and the TX themselves are quite important when using these marvellous shunts.
Instead of using a zobel between the TX and the diode bridge I always found that using HEXFREDS provide the best results. The major differences are in the treble and it is there that this preamp excels.
Could you explain how you use HEXFREDS, I would like to learn new thing, new at least to me. I used some extra fast soft recovery diodes too.
I found that using HFA15PB60 intead of the "usual" schottky produces a fast but less edgy sound in low power applications.
The soft recovery characteristic impairs the TX tendency to oscillate at high frequencies during diode shut down periods so I do not need the "taming" zobels that (if not precisely done) can dull the sound.
Another very important part is the smoothing cap..... initially I was convinced that the shunt would be impervious to the TX / diode / cap combination before it because it works with a CCS with very high PSRR, but that is not true.
Smoothing caps can easily be heard before the shunts. The effect / difference is quite dramatic. You can experiment just by bypassing the smoothing cap with some styrenes.
IMO bypassing is quite an art and in the psu is very difficult to tame so the best bet is to use 4 pole caps with high capacity. Sounstage width increases enourmoulsly when using some special models.
Another area I did not "touch" yet id the termination of the shunts..... you use a 100u 0.1r zobel but I believe your shunts could stand a 0.2r 4.7u film.... what do you think ?
The soft recovery characteristic impairs the TX tendency to oscillate at high frequencies during diode shut down periods so I do not need the "taming" zobels that (if not precisely done) can dull the sound.
Another very important part is the smoothing cap..... initially I was convinced that the shunt would be impervious to the TX / diode / cap combination before it because it works with a CCS with very high PSRR, but that is not true.
Smoothing caps can easily be heard before the shunts. The effect / difference is quite dramatic. You can experiment just by bypassing the smoothing cap with some styrenes.
IMO bypassing is quite an art and in the psu is very difficult to tame so the best bet is to use 4 pole caps with high capacity. Sounstage width increases enourmoulsly when using some special models.
Another area I did not "touch" yet id the termination of the shunts..... you use a 100u 0.1r zobel but I believe your shunts could stand a 0.2r 4.7u film.... what do you think ?
I am not sure, my ears are quite old and I am afraid I could not hear the difference, and here I don't have young audio enthusiast to help me with this. Maybe you can experiment and tell the result?
Young audio enthusiast ?
Old ears ?
I was born in 57... remember 250 GTO ?
I am not old, mind you.
You are not old, you are knowledge full.... I wish I knew 1/500 of what you have to give.
PS: The truth is I am getting blind and in return nature is giving me back an exceptional hearing capability. I can detect the nuances of the different components sonic signature easily.... but I am having increasing difficulties with soldering....
Old ears ?
I was born in 57... remember 250 GTO ?
I am not old, mind you.
You are not old, you are knowledge full.... I wish I knew 1/500 of what you have to give.
PS: The truth is I am getting blind and in return nature is giving me back an exceptional hearing capability. I can detect the nuances of the different components sonic signature easily.... but I am having increasing difficulties with soldering....
Last edited:
Still, you are 13 years younger then me, my hearing is not gone to much but not so good as 13 years ago.
And you are to kind.
- Status
- Not open for further replies.