• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

My new amps: Jack Elliano, Bud Purvin, Asnain Kolarkar

Hi all,

Thought that I would show off my new amps that I have been enjoying the past few days.

These amps are results of a collaboration between Asnain Kolarkar, my close friend , and the two famous gurus , who need no introduction.

Asnain is here in India and is an expert in transformer design and winding, and also very good at designing circuits.
He is based in India and runs a hobbyshop , Kolarkar Audio research, to cater to his interests. He has been in touch with both Jack and Bud since the last few years , and considering his knowledge and skill levels , they have authorised him to carry on with their work and designs.

So what do I have ?

1) 6AQ5 amp
Jointly designed by Bud and Asnain , this is a SE class A amp that is running the 6AQ5 power tubes in UL mode. Output is 3.25 WPC with frequency response 17Hz to 60K . No feedback has been employed, and distortion levels are vanishingly low. The driver is 6N2P , tube rectification can employ most of the octal rectifiers.

2) EL84 amp in A3 topology
SE in A3 topology is Jack Elliano's proprietary design. What I have is an EL84 amp in that configuration, punching out 10 wpc😱🤩


Both the amps are very musical , with a superb bass punch

3)
Jack Elliano's PVA

Passive voltage amplifier, that deals with impedance mismatch between the source and power amp input. It takes a low impedance input upto 600 Ohms and presents a 47k output. This has gain factor of 1:4 . It is most useful for pairing a degital source with a tube power amp.

Here are some pics.

IMG_20230912_053435487_HDR.jpg IMG_20230912_053504004_HDR.jpg 😊
 
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Nice looking builds. Interesting looking speakers as well.
I built Jack's PVA using his signal transformers. Worked well for me between my Oppo and a 6A3 A2 PP design by Jack. Used his iron on those monoblocks as well.
Good to know someone is working with Jack. Regards, Bill
 
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Nice looking builds. Interesting looking speakers as well.
I built Jack's PVA using his signal transformers. Worked well for me between my Oppo and a 6A3 A2 PP design by Jack. Used his iron on those monoblocks as well.
Good to know someone is working with Jack. Regards, Bill
Thanks,

The speakers are Philips AD5200M full range drivers. Jack strongly suggests pairing high sensitivity speakers with these amps , and at 98db , the Philips drivers are a very nice match.

Regards,

Anwesh
 
analogadikt,

Your system looks great!
I am sure you have fun listening.
It is nice to have more than one amplifier to change out from time to time.

I do want to point out that Ultra Linear is a form of negative feedback.
However it is one of the most local types of negative feedback . . . Only the beam power tube and the output transformer primary are involved, no other circuitry in that very local feedback loop.
The same can be said for Ultra Linear using a pentode tube.

A simple way to look at it is:

Pentode/beam power tube modes are 0% negative feedback, if no negative feedback circuitry is applied.

Pentode/beam power tubes in Ultra Linear mode percent negative feedback is according to the Ultra Linear Tap, 40% negative feedback for example, if no other negative feedback circuitry is applied.

Pentode/beam power tubes in Triode Wired mode are 100% negative feedback, if no negative feedback circuitry is applied.

It is a function of how much the screen (signal) voltage changes, according to the signal voltage changes of the plate.

And all this is before any other negative feedback is applied (if it even is applied).
 
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#6A3sUmmer
#5

A3 is new way of making tube amps all credits to jack elliano sir ( eletra print audio)
And you know jack sir very well..

You seems to think that the UL tap, for the
screen's, is negative feedback?? It is NOT!!
In fact if it was out of phase the transformer will not work at all!!! all
will cancel out!
If you just used a scope you would find out that the screen grid signal is "IN
PHASE " with the plate of same tube.
The screen grid, if you looks into the GE tube books you will see that the
screen acts, in UL, as an "accelerator" and increases power obeying electron
speed in square law ( x 4).

If still you have any questions you can ask jack sir. Happily..


Regards
Kolarkar audio & research (🇮🇳 india)
 
Oh well, please tell us what happens when one connects the G2 to the plate of the tube. Clearly the same phase, does that increase power as well?

Do you happen to have a link to the patent for A3 by Jack Elliano? I saw it mentioned a couple of times, but never the actual thing. Just a number is enough, I (and everybody else) can find my way through USPTO and/or google patents.
 
The screen grid, if you looks into the GE tube books you will see that the
screen acts, in UL, as an "accelerator" and increases power obeying electron
speed in square law ( x 4).
Yes, but it's also somewhat an anode, and somewhat a control grid. The idea that G2 is somehow like the accelerator in a CRT, with anode a handspan away, isn't realistic.

It's probably most useful to think about G2 primary taps the way the credited inventor Blumlein (who invented everything, almost) did, as on a continuum between anode and B+. At any random point on the continuum, any percentage of primary turns, the output valve has different characteristic curves, IOW, is a different valve.

All good fortune,
Chris
 
I do not see the quote button under reply #7 above but I am a person with very shallow pockets that are sometimes even outturned ha ha ha so if anyone is interested in a transformer set for the JE amp seen in post #1 please contact me.

Regards,
To clarify,

I have one complete EL84 amp that I am thinking of selling to finance another project, I am not selling transformers.

Regards,