Hi Ian
Its possible to downshift the voltage range and simple to do. Just replace R9 & R10 with 33K 1W each. Only watch Q1's little sink temperature because you will drop much voltage across the CCS when considering your low Vout range and your particular input voltage level. Be frugal on spare current setting at least so to keep Q1's dissipation in check.
Regards
High, I am a fairly new to DIY and need some advice regarding shunt regulator.
I was thinking of adding this shunt voltage regulator for my Bottlehead Crack amp already speedballed. The bottlehead guys made another crack model "crackatowa" with a shunt voltage. I didn't want to build another kit, just to add a shunt voltage regulator, I also didn't want a bigger amp taking up my deskspace either.
So I could use this shunt voltage regulator kit from K&K for my bottlehead crack instead right? I'd need to get a hold of the crackatwoa schematics, also is there any advantages/disadvantages using mosfet vs tubes for shunt regulator?
Thanks
I was thinking of adding this shunt voltage regulator for my Bottlehead Crack amp already speedballed. The bottlehead guys made another crack model "crackatowa" with a shunt voltage. I didn't want to build another kit, just to add a shunt voltage regulator, I also didn't want a bigger amp taking up my deskspace either.
So I could use this shunt voltage regulator kit from K&K for my bottlehead crack instead right? I'd need to get a hold of the crackatwoa schematics, also is there any advantages/disadvantages using mosfet vs tubes for shunt regulator?
Thanks
The K&K kit is directly inspired from this thread but I have not had it in my hands even once so to know details.
In general there is no reason to think there is a quality disadvantage in using MOSFETS for the high voltage rail.
To the contrary there are technical performance advantages to exploit.
A downside is that semiconductors are easier to break than tubes when misused. But much cheaper and easily available to replace.
When used well and kept cool enough they can outlive tubes though. You must be careful with their isolation to metal parts especially in HV applications.
Better contact the K&K company for your specific questions regarding your preamp and their PSU kits compatibility plus the proper guidelines of use.
In general there is no reason to think there is a quality disadvantage in using MOSFETS for the high voltage rail.
To the contrary there are technical performance advantages to exploit.
A downside is that semiconductors are easier to break than tubes when misused. But much cheaper and easily available to replace.
When used well and kept cool enough they can outlive tubes though. You must be careful with their isolation to metal parts especially in HV applications.
Better contact the K&K company for your specific questions regarding your preamp and their PSU kits compatibility plus the proper guidelines of use.
The 10uF is a noise filter. 10uF is good enough for size and filtering to can use MKP and it does not accumulate much energy to become dangerous for the circuit in most transients. The 0.33uF is important for value because it terminates the closed loop transfer function for a certain shape and phase margin. It can be up to 0.47uF without much of a problem though. I.e. you can try your C2 4.7u and 0.47u C1 subjective alternatives without danger.
Just to clarify, for upto 500v B+ i only need switch out Q1 for the IXYS part and fit 600v rated film caps?
I chickened out. It seems that both values are there for a reason. But I have bypassed the C2 10uF MKP with a little russian teflon cap and it sounds promising. More clarity and focus - we'll see with a little more burn in and a little less placebo the next few days.
I bypassed all my SSHV2 C2 with FT-3 0,1uF 600V, not placebo effect: sounds better and after 300 hours or more will improve the SQ.
By George I did it! I had two 4.7uF Mundorf silver capacitors and butchered a not used amplifier for two more. I piggybacked two and two (I'm using two Salas' in my home made 1541a DAC). The capacitors has had some previous use but probably needs a little settling time with the new voltage regimen. I'll get back to sound impressions when my ears are fully rested. Probably tomorrow. And Salas - of course you are right. Way to expensive, but in my case I choose to regard it as a form of recycling.
Ok, that didn't work out so well. The Mundorf Silvers weren't any better than MKP's and teflons. A little more details but nowhere justifying the price difference. In fact after a while I preferred the somewhat "dryer" and cleaner tonal balance of the MKPs with teflon. Really surprising. I'm guessing one or two reasons: Either MKP's with teflon bypass are better than Mundorf in this position or Mundorf is letting through more of the garbage from the power supply. I will build another PSU for the Salas and investigate it's transparency for supply changes. I'll be posting my results tomorrow.
New update: My previous PSU was a Graetz hybrid PSU with a LCLC-filter before the Salas'. The first C was a russian 10uF red bathtub capacitor and the last C was two 100uF SCR polypropylene capacitors (one for each shunt regulator). The new PSU is a LCLCLC-filter with the same mains transformer and rectifier and 20H Hammond chokes as before plus a new one, and the C's are replaced with only Mundorf Silver in oil 4.7uF capacitors. So any differences except that the "raw" voltage out went down 10V? Yes - this time everything changed for the better. No doubts and no second thoughts. The clarity and details improved with no negative side effects (read: harsher sound), and the flow in the music improved quite substantially with no slowing down and loss of PRAT. The music just sounded more natural. And it bloody well should since the PSU is now using more expensive parts. And finally - no - a shunt regulator does not make the power supply immune to improvements earlier in the PSU chain. Not really a "bombshell" conclusion but there it is.
Working perfectly with ~450v B+, 300v out, and set for 40ma. IXTP08N50D2 for Q1, 100k R9 and R10, and 600v rated caps for C1 and C2.
You should add that setup option into the documentation as i am sure i am not the only one who would like to run a higher supply voltage.
Thanks again for the help..