Tube Voltage Regulator, Is it worth the effort?

[sgerus]

Tube Voltage Regulator, Is it worth the effort?
I’ve been experimenting with tube based voltage regulators for my next amp, which will be 2A3 or 300B (switchable) SE stereo amp.
See this link from JC Verdier more details on the tube voltage regulator tech300B
My first impression is it’s not worth the effort…. But I’m still undecided and looking for feedback.
You will see from the test data below that I never got down to the less than 1R z-out as the JC Verdier article indicates….
My B+ for the baseline of this test was based on a LC-RC PSU (10H,60uf-200R,100uf)
If I add 200-400uf to the LC stage of this psu I get roughly the same Z-out numbers as with a VReg psu
Could I hear the difference? I can’t say because I didn’t do a side by side blind test.

Here is the test setup:
The input to the amp is a sine wave at full power, from 20hz to 5Khz
100R in series with the OPT used to measure the AC voltage drop and calculate the AC current
The AC current was very constant from 20hz to 2Khz, at around 40ma
AC voltage measured at the B+ via a 30uf/1M RC filter
Z-out is calculated by = Vac/Iac
The psu for the V-reg test was: 10H,60uf – Vreg – 100uf
Here are the test results (Z-out in ohms) that compare several LC-RC power supplies to the V-Reg power supply:
The first 4 are normal LC-RC types, then a solid state test just for grins, the 2 examples of tube based voltage regulators, the first using a 5V zenner diode for the voltage reference, the 2nd using a 0C3
PSU Config
#1 10H,60uf-200R,100uf
#2 10H,260uf-200R,100uf
#3 10H,460uf-200r,100uf
#4 LM317 (ss) V-reg
#5 6AS7,6SG7,5V zenner
#6 6AS7,6SG7,0C3

20hz 50hz 100hz 200hz 500hz 1Khz 2Khz 5Khz
#1 50.0 29.5 15.6 8.0 3.1 1.5 .96 .84
#2 18.3 9.75 5.11 2.47 1.0 .52 .31 .18
#3 11.2 5.75 2.82 1.44 .58 .31 .18 .12
#4 45 19 10 6 4.2 3.4 3.3 3.3
#5 23.9 18.5 12.8 7.4 3.1 1.4 .57 .15
#6 19.2 14.5 11.8 8.7 3.1 1.3 .51 .21

[Gordy]

That's interesting.

I find that most folks who swear by tube regulated power supplies actually do it for reasons of tradition and sentiment (i.e. psychological bias) rather than for actual / pragmatic reasons. Personally I have had fine results using solid state regulation based on the Maida (augmented 3-terminal device) regulators. I have not measured the output impedance though.

Jan Didden (who usually hangs out in the Solid State and Power Supply areas of the forum) recently authored an interesting article in Elektor magazine that combined a solid state error amp and vacuum tube pass element. It has a sub 0.5 Ohm impedance across the audio band. (Elektor March 09, page 22, "T-Reg".)

[Geek]

Still, I like them.

If we were interested in perfection though, we wouldn't be using tubes at all for anything

Cheers!

[janneman]

Originally Posted by Gordy

[snip]Jan Didden (who usually hangs out in the Solid State and Power Supply areas of the forum) recently authored an interesting article in Elektor magazine that combined a solid state error amp and vacuum tube pass element. It has a sub 0.5 Ohm impedance across the audio band. (Elektor March 09, page 22, "T-Reg".)

Actually, it's sub-100 milliohms Zout and sub-300 uV hum/noise

http://www.linearaudio.nl/t-reg-1.htm

jd

[Gordy]

Originally Posted by Geek

Still, I like them.

If we were interested in perfection though, we wouldn't be using tubes at all for anything

Cheers!

"And they look really nice"

: )

[kmtang]

Are there famous commercial high end tube power amps with stabilized power supply for the B+? I have not seen them yet. If it is more superior, there should be some out there.

Please correct me if I am wrong. In fact, I really like to try but I still have not got the chance yet.

Johnny

[quanghao]

[QUOTE=janneman;1954592]Actually, it's sub-100 milliohms Zout and sub-300 uV hum/noise

http://www.linearaudio.nl/t-reg-1.htm

ok! thank ! I change tube 6080 by 6H13??? what do you thinK???
thank,

[sgerus]

Originally Posted by kmtang

Are there famous commercial high end tube power amps with stabilized power supply for the B+? I have not seen them yet.

Check out this link.... this is what got me started on the Tube Based V regulator test.

Triode Spirit

[GK]

For a lot of audio applications (especially tube) an ultra low output impedance isn’t of much significance. A linear regulator is an inefficient, but extravagant means of eliminating hum.

[janneman]

[QUOTE=quanghao;1954672]

Originally Posted by janneman

Actually, it's sub-100 milliohms Zout and sub-300 uV hum/noise

http://www.linearaudio.nl/t-reg-1.htm

ok! thank ! I change tube 6080 by 6H13??? what do you thinK???
thank,

That'll work fine, looking at the specs. I haven't checked the pin-out though, so that's something you'd need to verify.

jd