Simplistic mosFET HV Shunt Regs

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#1,441
kacernator said:
Hm, interesting project. Is this just aikido preamp?
I am planing using HV shunt regulator also with aikido. What are your observations about sound quality you gained with aikido?
Click to expand...

It's Aikido preamp with a little twist. Since I used 12AU7 at the input gain stage and 12AT7 at the output buffer stage, the overall voltage gain that the circuit design could achieved was only 17.6dB which was slightly lower than what I needed. My objective was at least 22dB under 20k Ohm load and no negative feedback. Because of that I added a simple JFET gain stage to feed the input of the Aikido preamp in order to boost overall gain to about 24dB.
That was why, in addition to the HV shunt regulator, I also got a Salas's LV bipolar shunt regulator to power the JFET stage in the same preamp project.

"Silent and dynamic" are the best words that I could think of to describe the benefit directly related to the use Salas' shunt reg design.
 
#1,442
jtcc1015 said:
It's Aikido preamp with a little twist. Since I used 12AU7 at the input gain stage and 12AT7 at the output buffer stage, the overall voltage gain that the circuit design could achieved was only 17.6dB which was slightly lower than what I needed. My objective was at least 22dB under 20k Ohm load and no negative feedback. Because of that I added a simple JFET gain stage to feed the input of the Aikido preamp in order to boost overall gain to about 24dB.
That was why, in addition to the HV shunt regulator, I also got a Salas's LV bipolar shunt regulator to power the JFET stage in the same preamp project.

"Silent and dynamic" are the best words that I could think of to describe the benefit directly related to the use Salas' shunt reg design.
Click to expand...

Why didnt you use 12AX7 as input tube for gain cca 30dB?
 
#1,444
Preamp tube heater reference

Hello,

Regarding the Salas design/Quanghoa PCB:

Where is the reference for the elevated heater reference picked up? One can typically use the heater supply ground to the HV + line, but I'm not familiar with the shunt regulator topology and wondering if some other scheme is needed.

Thanks!
Gary
 
#1,446
Salas,

Thanks for taking the time to reply. I've been following the thread(s) on your regulator design for a while and thought I'd give one a try on my John Broskie Aikido. Didn't want to re-invent the wheel on a PCB so thought Quanhoa's would be a good place to start.

My question was purely in reference to the design, and not the PCB. I've used linear regulators in HV designs and floated the heater supply's ground to that, and curious if I could do the same on a shunt regulator without issues.

Gary
 
#1,448
Recently a friend and member here, floated it for a Valve Itch phono he assembled for instance. Not strictly on a QH board though. Didn't say he got any issues.

P.S. I think they float from output on dvb projekt's tubizators also.
 
#1,458
More listening impressions

So I have Salas HV running with aikido for few days and I have mixed feelings about it. With regulator it is somewhat clearer, bass is very tight, it has wider image but overall sound is dead, lifeless, it doesnt breathe. In fact I enjoy unregulated supply more, it seems to me more musical.
I am not saying Salas regulator is bad, my ears prefer unregulated sound.
 
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