Gary already tested a depletion Mosfet Q1 with 500V spec, 840 is already 500V, the cascode BJTs are 300V each. Higher than 68K ref resistors would help also. BUT going to the edge of parts spec is usually challenging them, I can absolutely NOT guarantee the PCB HV creeping distances since its not made and tested for such voltage range.
I just tried out a SSHV2 board in a compressor I am buildling. Before I had a pretty good S/N or about -80dB with a pretty basic RC filtered supply, with the SSHV2 board in this doesn't improve at all. I was expecting quite a large improvement... I have no way of measuring the ripple of the first supply other than modelling it, but from what I have read the SSHV2 is in the micro volt region which my supply wouldn't be.
What noise floor are other people measuring with the boards? I am happy with -80dB but thought it is worth asking.
I may need to rework the layout to improve mine, or maybe the circuit has a good enough PSRR for it to not be a factor?
Many thanks
Charlie
What noise floor are other people measuring with the boards? I am happy with -80dB but thought it is worth asking.
I may need to rework the layout to improve mine, or maybe the circuit has a good enough PSRR for it to not be a factor?
Many thanks
Charlie
If your noise was not of harmonic nature in the first place, then the PSU would have nothing to improve in that aspect. Beyond that, say a phono stage and a line preamp would have a different intrinsic random noise floor regarding self noise and so it goes. To see a general drop it would mean there was a previous white noise like contribution from some PSU that manages to penetrate due to low PSRR, and from a passive its highly unlike. Focus on possible dynamic changes you can sense or not.
OK, I think there is still room for improvement so I will look at the layout etc.
I thought it is worth trying out better regulated supplies on classic valve compressors, why should you hifi guys have all the fun!
Hopefully getting some studio time this week so I will report it's performance.
Thanks
I thought it is worth trying out better regulated supplies on classic valve compressors, why should you hifi guys have all the fun!
Hopefully getting some studio time this week so I will report it's performance.
Thanks
Salas...if you remember, with your help, I have added a SSHV2 to my CCS (C4S) loaded VT-25A line amp. Adding the SSHV2, all hums are gone....however, a light zzzzzssssszzzz....takes over....(which I can live with, although my friends cannot....)....I think this could be because of old tubes.....Salas, what you think??
And with the SSHV2 added, I feel that the music has become a bit restricted...less lively....less fluid.....what I think is I should get rid of the C4S, and instead going back to use resistors to load my tube with your SSHV2.....with a good quality resistor after your board, it should act like a CCS anyway, with the added avdvantage of setting the loading current (voltage across the resistor) easily with your board......
Your board opens up opportunities for me to fine tune my amp with much less fuss and more joys.
Will report back further later....thankyou....
And with the SSHV2 added, I feel that the music has become a bit restricted...less lively....less fluid.....what I think is I should get rid of the C4S, and instead going back to use resistors to load my tube with your SSHV2.....with a good quality resistor after your board, it should act like a CCS anyway, with the added avdvantage of setting the loading current (voltage across the resistor) easily with your board......
Your board opens up opportunities for me to fine tune my amp with much less fuss and more joys.
Will report back further later....thankyou....
In many cases, the SNR, or noise floor, of various stages, is being determined by the stage itself. When the tubes, power supply isolation from the stage and layout in a certain stage have certain noise floor, the noise floor will not improve beyond the intrinsic noise floor of that stage, no mater what we will to the power supply (other than, perhaps, putting the power supply in a different case and improving the layout).
Yet, the quality of the power supply have great impact on the sound quality, beyond the measured SNR.
Do you know of an HV regulator that may be better than the Salas HV regulator?
Yes, I think I was just expecting to see an improvement. It is clear that the previous PS was good enough for the circuit with respect to ripple. I will try to improve on the -80dB by changing the layout.
No, I did mean that I wanted to try this board as it is one of the best I have seen/heard (but that's not saying much). I would also like to try a Gary Pimm style CCS - VR or similarly Morgan's statistical reg.
No, I did mean that I wanted to try this board as it is one of the best I have seen/heard (but that's not saying much). I would also like to try a Gary Pimm style CCS - VR or similarly Morgan's statistical reg.
zzzz means you gotta sort out some small ground loop somewhere or some tube problem that surfaced better after the hum blanket has gone.
Try the resistor indeed.
There may be improvement in sound quality, while there is no improvement in measured SNR. Measured SNR isn't all that affects sound quality.
With resistors loading the tubes, do you think it is better to use 2 SSHV2 boards??
My PSU box only has space for one SSHV2 board....what would be the best way to connect the 2 resistors please??....I am sure you always have something up your sleeves....
Strange as it may sound....I will need you to walk me through as how to open a thread......
I welcome your thoughts the most.....
