• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

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#61
Tubelab_com said:
That's not what I see. Expecting them to pass 15 watts at 20 Hz will result in some serious saturation which sounds quite nasty. Run them in the 5 watt and under range and they do quite well. I spent several hours last night cranking an UNSET based SE amp running 6AV5 TV sweep tubes through a very old pair of XSE15's into my Yamaha NS-10M Studio monitors which are in the 12 to 20 ohm range below 100Hz. These things ROCK! The results were reported in post #583 here:

https://www.diyaudio.com/community/threads/unset-beta-board-build.376124/page-30#post-7741108

Since the setup was still on the bench, I measured the 3db roll off points at 2.5 watts of output. They are 18Hz and 56 KHz.
Click to expand...
Not to derail the thread but it does make me happy to see you revisiting the 6av5. It was your posts about that tube and Edcor transformer that brought me to this site all those years ago. I have finally been able to use the 12av5 tubes I bought back then. Run them in ultralinear PP around 300v and 40(?)ma. Using 8k Monolithic Magnetics output transformers. I have no idea how they measure but they sure do sound good🙂
 
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#62
Jack would make you tell him a lot about your design before he would make you a transformer, which was pretty obnoxious. When I showed him my high-feedback SE design it just didn't compute for him. He told me that the designer was all wrong and that none of his distortion measurements were real (the designer was me, but I didn't bother telling him that). In the end, I had to resort to just disengaging and telling him what he wanted to hear to get him to just shut up and wind.

In the end, I would have preferred a transformer with a bigger core and would have paid much more to get what I wanted out of the exchange. But he was a terrible listener and always knew better than the customer. What good was all of his experience and knowledge to me if he wouldn't wind the transformer I was trying to buy?

Maybe he was great to work with if you are doing something pretty vanilla, but trying to work with him on something innovative was highly frustrating.
 
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#63
Stephe, which tubes are you running in the output? They claim to support 6L6, EL34 and KT88 from what I see.

I liked the CXSE 5W with in the amp with 6P1P output tubes, and built two amps in that configuration.

When I built with 6P41S, I found the CXSE lacking bass and switched to the GXSE 15W. I have built three amps with the 6P41S output tubes driving the GXSE 15W outputs (5K:8R as well as 3.5K:8R) and people (Family) have been very happy with them. I have also tested them with 6L6 UL mode, as well as 300B and found for the money they were a reasonable output transformer. Certainly there are better, but at 3-4X the cost.

I would class thee CXSE as comparable to the transformers used in the likes of Magnavox, RCA, etc console SE stereo systems from the 50s and 60s.

Unless one is really cost restrained, I would recommend the GXSE 15W series for small SE stereos. The exception being if one were going to build with EL34, KT88, 2A3, 300B, etc where the tubes justify more costly OPTs.
 
#64
TheGimp said:
Stephe, which tubes are you running in the output? They claim to support 6L6, EL34 and KT88 from what I see.
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They look like older Sovtek 6550As. Those red metal RCA 5693's are real tasty tubes. I have a couple of them somewhere.

After engaging my brain (the clutch slips a lot), I realized where the discrepancies in our measurements may be coming from. In elecronics classes some 50+ years ago I learned that the Q of any resonant circuit can be lowered by adding resistance. So, if the resonances formed in the OPT due to leakage inductance and lack of primary inductance cause a steep rolloff in the response at both ends of the audio spectrum we can flatten them out a bit by putting a resistor in parallel with the OPT. Now just adding a resistor is a waste of power, but we already have one. It's the Rp of the driving tube. We can choose a low Rp tube like the 300B, or we can lower the Rp by triode wiring a pentode or adding feedback. The low screen grid voltage ratings of most TV sweep tubes make triode wiring impossible or unstable at high B+ voltages. The board seen driving the little Edcors is an UNSET board which has a resistor directly between G1 and the Plate to make the pentode look like a low Rp triode. The drive signal is applied to the cathode. I have not attempted to determine the approximate driving impedance afforded by the 6AV5 in UNSET, but the 26HU5 (a 40 watt sweep tube) is in the few hundred ohm range.
 
#65
SpreadSpectrum said:
Jack would make you tell him a lot about your design before he would make you a transformer, which was pretty obnoxious. When I showed him my high-feedback SE design it just didn't compute for him. He told me that the designer was all wrong and that none of his distortion measurements were real (the designer was me, but I didn't bother telling him that). In the end, I had to resort to just disengaging and telling him what he wanted to hear to get him to just shut up and wind.

In the end, I would have preferred a transformer with a bigger core and would have paid much more to get what I wanted out of the exchange. But he was a terrible listener and always knew better than the customer. What good was all of his experience and knowledge to me if he wouldn't wind the transformer I was trying to buy?

Maybe he was great to work with if you are doing something pretty vanilla, but trying to work with him on something innovative was highly frustrating.
Click to expand...
When I had him make a pair of PP transformers it was similar. When I stuck to exact specs and a schematic he approved of it went smoothly but when I sent a compliment and questions about if the different specs of his transformers would be an improvement to a SE transformers I already had in another amp, it went south fast and I just stopped emailing.
The transformers sound great, although the varnish smell was really strong for months. I left them out in the hot sun day after day and it took a long time to fade.

Even if he could be a grumpy, opinionated person, his skill will be missed. If you are good enough, you don't have to suffer the idiots like me emailing questions 🙂
temp.jpg
 
#66
I messaged Jack about transformers he had on Ebay and he mentioned he still had some materials to wind new ones. Prices are high based on materials and I don't know whether he has materials to make everything he used to. But if you are looking, it might be worth reaching out.

Based on this thread, George's great contribution to us all with the TSE-ii and Stephe's inspiration with transformer shootouts, I'm hoping to have some results up soon comparing SE 5k outputs, including the Monolith's that were recommended here (and elsewhere), the new(ish) Antek OPTs, a pair of Edcor GXSEs I have sitting in a Tubelab SSE, and the tiny Tamradios that enjoy some occasional enthusiasm. The amp is running on the bench. I hope to sort out test rig issues (also Stephe inspired) next weekend, though my projects often take months or years longer than expected. I'm especially curious to see how the Anteks do.

Paul
 
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#71
analogadikt said:
Asnain Kolarkar isnow making the A3 amps ( a Jack Elliano design) here in India and works under the guidance of Mr. Elliano.
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I have the schematic and OPT's for that amp sitting in my work room, which Jack sold me shortly after he announced he was closing shop. I've been sitting on them, partly over the apprehension of dealing with a B+ of 650V, but mainly the difficulty of sourcing the non-standard power transformer. Maybe this new venture might rectify that last problem?
 
#74
Hello every one
Asnain kolarkar here from kolarkar audio
Thanks @analogadikt for kind words.
Yes all i learnt from Jack Elliano sir's guidance .and Bud Purvine sir of( o-netics) they both are my tutors every thing I learnt from them

Yes I have all the rights from jack elliano sir to make A3 amps.

You Can contact me here on diy audio by dm .... happy to meet your requirements.

Regards
Asnain kolarkar
Of kolarkar audio
 
Last edited:
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#79
analogadikt said:
It is the link to the Instagram page of Kolarkar Audio Research (India) . Click on the blue letters to open it. One does not have to be an Instagram subscriber to view it. Asnain Kolarkar isnow making the A3 amps ( a Jack Elliano design) here in India and works under the guidance of Mr. Elliano.

Regards,

Anwesh
Click to expand...
If it ain't on "the net" it does not exist for me.
If i should deal with someone i would like a real phone number, a real website and a physical address and also
some real banking info ( paypal ebay mastervcard/visa or a bank account).
 
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#80
@petertub

Youhave quoted my one day old post (#70). After that , Kolarkar has himself joined this discussion (post #74).You could have asked him for these details or DMed him.
But okay , here ya go😎

ADDRESS

Asnain kolarkar
(Kolarkar audio research)
Near Shastri chowk
Qureshi masjid
City- Shahabad Gulbarga district
Karnataka, INDIA 585228

Phone +nine one nine seven four zero four three four seven four six

Email/paypal : asnainkolarkar nine seven four zero at gmail dot com
Delete spaces from above for actual use

BR
 
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