High Fidelity Tube Amplifiers Build, 99% Made in India…

[yogibear]

The first amp is 6BM8 Single Ended Pure Class A, 6AX5GT tube rectified, no NFB and makes a clean 1 watts per channel. It’s a fully dual monoblock design under the hood with choke filtered power supply. The output transformers are customized and well mated to the topology and were hand wound in India and have been scope tested as 30hz to 17k frequency response @1 watts with 0.4 % distortion. The output taps are for 8 ohms impedance speakers. The amp drives any full range or 2 way setup at 93dB and above with no dearth of loudness or low end. The OPTs were designed under guidance and blessings of “Bud Purvine Sir”, from US.






The second amplifier is Mullards 5-10 clone which features EF86 tube at driver stage, 12AX7 for phase inversion and two EL84 in Push Pull mode. The amplifier makes 12 watts per channel and accepts 4 and 8 ohms impedance speakers. Drives anything at and above 89dB.

The amp features finest Push Pull OPT you can lay your hands on, speced at 8hz to 50khz @5 watts, with 0.05% distortion and a perfect phase response. They were hand wound in India using finest material and again under aegis of “Bud Purvine Sir”.

Both the amps were built from scratch with minimal hand tools.

I hope to build more interesting valve amps using some exotic tubes and very interesting topologies including a very fine sounding DHT Tube preamplifier. Will share them as I go forward in my passion…. It’s a journey filled with great fun and learning, de-learning never stops…

Feel free to voice your critical comments…

 

[tnvijay]

That's a nice build! I started my tube diy journey a couple of years back. My first was a SE ECL82( 6bm8) in a schade feedback configuration ( no global feedback)... As rightly said,it is 1 to 2 watts, but it is pure bliss.... My second attempt will be on super triode configuration with same 6Bm8 - coming soon.. The First ECL82 is happily singing in a fellow forum members home

My second is again a SE but with PL504, and ECC83 as driver.. I wound both Power transformer and OPTs on a small handwinder... Lucky to get some guidance from a Veteran tube amp builder from Portugal, who generously guided me whenever i had doubt.. With a humble oscilloscope and few multimeter, I adjusted the AIRgap in SE OPT to achieve maximum bandwidth.. The amp gives surprisingly loud bass ( 6watt RMS) .. This again is a Local feedback ( schade) ,but undergone meticulous tuning to suit my taste..This is the current amplifier i am using to hear music daily...
It gives immense satisfaction to build everything from scratch- from. Chasis to woodwork.. From soldering to transformer winding. It is indeed a slow and steady journey, But nothing would match the experience of listening with tubes( i am of course saying my perception and opinion!)
It is a addictive hobby. I started with a small handwinder ,now bought a professional transformer winding machine,just to wind Output and power transformer for the various tube projects

Next in line
Push pull ECL86 ( Famous Baby Huey circuit)
Push pull PL504/ECC83/82
will be happy to post as i progress
Attached herewith are some pictures both work in progress/ completed/ Transformer winding images - in no particular order

 

[yogibear]

That's a nice build! I started my tube diy journey a couple of years back. My first was a SE ECL82( 6bm8) in a schade feedback configuration ( no global feedback)... As rightly said,it is 1 to 2 watts, but it is pure bliss.... My second attempt will be on super triode configuration with same 6Bm8 - coming soon.. The First ECL82 is happily singing in a fellow forum members home

My second is again a SE but with PL504, and ECC83 as driver.. I wound both Power transformer and OPTs on a small handwinder... Lucky to get some guidance from a Veteran tube amp builder from Portugal, who generously guided me whenever i had doubt.. With a humble oscilloscope and few multimeter, I adjusted the AIRgap in SE OPT to achieve maximum bandwidth.. The amp gives surprisingly loud bass ( 6watt RMS) .. This again is a Local feedback ( schade) ,but undergone meticulous tuning to suit my taste..This is the current amplifier i am using to hear music daily...
It gives immense satisfaction to build everything from scratch- from. Chasis to woodwork.. From soldering to transformer winding. It is indeed a slow and steady journey, But nothing would match the experience of listening with tubes( i am of course saying my perception and opinion!)
It is a addictive hobby. I started with a small handwinder ,now bought a professional transformer winding machine,just to wind Output and power transformer for the various tube projects

Next in line
Push pull ECL86 ( Famous Baby Huey circuit)
Push pull PL504/ECC83/82
will be happy to post as i progress
Attached herewith are some pictures both work in progress/ completed/ Transformer winding images - in no particular order

Amazing ! We share same passion !

 

[grindstone]

You guys make me wish I was young again, sometimes Bud's thinking will definitely stretch your head--did he try to get you to ENABL your drivers yet?

Tip of the hat to both of you. The price of electrical steel and number of suppliers willing to work with low quantities has become so limited these past years that I didn't know more than a couple people were even trying anymore. BRAVO!!!

 

[yogibear]

You guys make me wish I was young again, sometimes Bud's thinking will definitely stretch your head--did he try to get you to ENABL your drivers yet?

Tip of the hat to both of you. The price of electrical steel and number of suppliers willing to work with low quantities has become so limited these past years that I didn't know more than a couple people were even trying anymore. BRAVO!!!

It surely takes a lot of effort, lots of learning, loads of investment and unlimited patience to create fine sounding tube amps. Afterall it’s a work of “art and science” ! I have been chasing my dream for last 5 - 7 years and now have just made a modest beginning… Let’s see how it rolls in coming months … years…

And at my age, sometimes back and knees shake a bit… But I will keep weaving….

 

[tnvijay]

It is indeed painstaking to find suppliers willing to sell low quantities- the best way is to make some casual talks, say that i am a hobbyist etc and ask for support. Thankfully I found one elderly gentleman who is willing to sell Bobbin and cores even for one pair of trafos... And copper wire, i try to get in bulk..it is this chasing for parts and doing at home that's what keeps the passion kicking alive! And what's more fun than tweaking your amp while watching the waveform on your scope!

You guys make me wish I was young again, sometimes Bud's thinking will definitely stretch your head--did he try to get you to ENABL your drivers yet?

Tip of the hat to both of you. The price of electrical steel and number of suppliers willing to work with low quantities has become so limited these past years that I didn't know more than a couple people were even trying anymore. BRAVO!!!

 

[drlowmu]

Cool to see this thread.

Yogibear, you said " feel free to be critical ". Thanks.

It is not important to me, from where the parts or work comes from, but rather, WHAT is the overall listening result ??

Guys, I won't ever use things like Schade feedback.

I disagree 100% about taking signals already amplified, and feeding them backwards into an amplifier's circuit, out-of-time.

Teach yourself how to do audio design at a higher level, but - also as simply and as honestly-good as possible.

Basic two-stage directly-coupled tube power amplifier circuits - when thoughtfully employed, do give me impeccable results, upon listening.

No feedback - anywhere. Heck, I have stopped using my scope. I do my design by listening to music's playback - on VOTT A7s, which if optimized, can become very exciting to hear.

While "everything" in audio is certainly important, I still find a power supply's design, its topology and total execution, is able to account for 90% of what ever audio performance we seek to have and to hear.

Continue to have fun, building for many more years. I have.

Jeff

 

[yogibear]

Cool to see this thread.

Yogibear, you said " feel free to be critical ". Thanks.

It is not important to me, from where the parts or work comes from, but rather, WHAT is the overall listening result ??

Guys, I won't ever use things like Schade feedback.

I disagree 100% about taking signals already amplified, and feeding them backwards into an amplifier's circuit, out-of-time.

Teach yourself how to do audio design at a higher level, but - also as simply and as honestly-good as possible.

Basic two-stage directly-coupled tube power amplifier circuits - when thoughtfully employed, do give me impeccable results, upon listening.

No feedback - anywhere. Heck, I have stopped using my scope. I do my design by listening to music's playback - on VOTT A7s, which if optimized, can become very exciting to hear.

While "everything" in audio is certainly important, I still find a power supply's design, its topology and total execution, is able to account for 90% of what ever audio performance we seek to have and to hear.

Continue to have fun, building for many more years. I have.

Jeff

Jeff,

It’s been now 5 years since I started putting together tube amps and till now they had been singing bare bone. Most of them with minimal or no feedback and one DC too.

It’s been now I made serious effort to house them and look decent too and it’s all DIY effort.

We have looked into and tested various OPTs, Sansui, Tamura, Acrosound, Macintosh, Fisher, to name a few and compared to ours on a professional Hantek scope. It makes little sense to talk about low end and HF response of a tube amplifier until you know how well the OPT itself performs on the scope. We even measure sine wave, square wave and distortion figures at higher power ratings, just to be sure there is nothing nasty with the OPT.

Of course listening tests are the final and deciding factor, afterall, all the effort is for the “love of music reproduction” and the hand wound OPTs do stand out in every aspect.

 

[drlowmu]

I was not critical of your hand made outputs !!!

Is it possible for you to send me good multiple view photos of the undersides of your amps, so I can study your lay out choices? It can be done in HFV FM mail if you wish, or just email me.

One thing to teach now. The RCA jacks should be within 2.5 inches of the grid of the INPUT tube, and in a place relatively free of magnetic fields. Not near transformers fields or any 240 VAC wiring !!! If those black pointer knobs are volume control pots, they should be VERY near the RCA jack inputs / input tube, to keep that signal wiring as SHORT as possible, to the input tubes' control grid.

The input wiring is the lowest - level signal in the entire amp, and more thought that I see pictured above, needs to be applied as to lay-out of same.

Also, Yogibear, many audio systems have a " centralized " attenuation means prior to the audio amplifiers. If so, I would avoid routinely placing any sort of potentiometers inside the audio amp, right after the RCA jack. Again, it is at THE smallest signal level and is UNamplified, thus most subject to signal degradation.

A fidelity loss / degrade, before it ever gets to the Input tube's control grid !! This is common sense stuff. My business college degree, and yours in the sciences, is not required.

If I had to use pots there, it should be two per channel brand new Precision Wirewound 2 Watt pots, maybe three turn, connected as a constant impedance 10K L-Pad. ( two Bourns 3547S-1AA-103A ) I can send you privately DIY data on this, if you so request.

The technique, if properly executed, can be VERY high in performance, maintaining the utmost in both signal integrity and control. If you degrade the source signal, before it even gets to the control grid of the Input tube stage, it is lost forever, not to be made up.

It matters very little how good anyone wound the amp's Output Transformer. See my point ?? You are doing very admirably, for only five years of tube DIY amp building. My first was in 1979, an Audio Note 300B DIY kit, built so to play 2A3s. Wow, 44 years ago. Photo??





Best wishes.

Jeff

 

[yogibear]

Jeff, no worries. I use common sense and very short wiring. Have experimented with various pots and one used are the best suited for maximum signal transfer.

OPTs are vital and bottlenecks, if they do not have wide frequency response, it’s makes little sense to try to optimize the rest of the amp and expect great results.

And a little bit of sacrifice for ergonomics and looks, doesn’t hurt the SQ.

Watch out for my next builds, you will be in more agreement..... (Zero sacrifice for looks, still nicer looking)

 

[drlowmu]

Jeff, no worries. I use common sense and very short wiring. Have experimented with various pots and one used are the best suited for maximum signal transfer.

OPTs are vital and bottlenecks, if they do not have wide frequency response, it’s makes little sense to try to optimize the rest of the amp and expect great results.

And a little bit of sacrifice for ergonomics and looks, doesn’t hurt the SQ.

What you just posted here is different to my experience and understanding.

It is impossible to have short wiring with the photo distances you showed us all, so how can you write " it doesn't hurt the SQ! You start your post by saying critical comments are welcome. Then you ignore them, and deny all.

You are not in tune with what I've experienced about the output XFRs' importance. Could be likely you have not heard a tube amp with a good power supply. Sorry no offense.

I could add economy / $30.00 USD SE output XFRs to either of the HFV written-up 6005 amps, and it will most likely totally / very easily be unlike anything you have heard.

Superiority starts from the RCA input jack, to the first 2.5 inches into the amp's internal lay out.





Jeff

 

[yogibear]

What you just posted here is opposite my experience and understanding.

It is impossible to have short wiring with the photo distances you showed us all, so how can you write " it doesn't hurt the SQ "???? . You start your post by saying critical comments are welcome. Then you ignore them, and deny all.

You are totally wrong about the output XFRs' importance, and do not even know it. Why? Because likely you have never heard a tube amp with a good power supply. Sorry.

I could add economy / $30.00 USD SE output XFRs to either of the HFV written-up 6005 amps, and it will most likely totally / very easily outperform anything you have heard.

Superiority starts from the RCA input jack, to the first 2.5 inches into the amp's internal lay out.

Jeff

Take it easy Jeff. I am more than 20 years younger than you and it’s perfectly fine to make a not so ideal start according to your books. Critical comments don’t mean that you all over again start telling everybody else that what you do and advocate is the end of the road ? Right ?

You are happy with your amp and speakers, I am super happy with what I am doing. And that’s matters most in DIY.

 

[drlowmu]

Wait a minute, be aware, all who commented above have not heard the system I'm referring to.

Always remember this above truth - my dear friends, and keep your cool.

Herb Reichert, independently for Stereophile, wrote up Dennis Fraker correctly, at RMAF 2016.

The truth, sets us all free. LLiu actually now hears it, maybe Hari does , to some degree, also.

Jeff in Missouri.

 

[prem]

And who’s Herb Reichert? Oh the guy who reviews on Stereophile. And going by his reviews, pretty much every piece of equipment he hears is exemplary. If it was Art Dudley, I would have at least given some concession. Having read most of Herb’s reviews, I wouldn’t buy a single piece of equipment based on his review.

 

[drlowmu]

God help us. Now we don’t have listening experience also. Almighty has been so unkind to us.

And who’s Herb Reichert? Oh the guy who reviews on Stereophile. And going by his reviews, pretty much every piece of equipment he hears is exemplary. If it was Art Dudley, I would have at least given some concession. Having read most of Herb’s reviews, I wouldn’t buy a single piece of equipment based on his review.

Dear Prem,

That is fully - correct, you have not heard anything made by my Audio Mentor, Dennis Fraker, or me.

Between us three, only me and Herb Reichert, to my direct knowledge, heard it at shows. Not Art. This includes Dennis' amps, Attenuator, GPA 604 MLTL speakers and even his wiring (Trios ).

Herb was given the Stereophile Editor's permission to write up Dennis, purely as a result of BOTH of them listening in Dennis' 2016 RMAF demo room. This ( HIGHLY UNUSUAL ) editorial mention was encouraged, despite the fact that Dennis was a SMALL Manufacturer, and he did no advertising at all, in Stereophile.

In a country the size of India, 1.4 Billion people, to my knowledge, not even one audio-enthusiastic individual has so-far bothered to DIY build TRIOS. " Guderbroad ", from Chicago, was so surprised - absolutely loves what he hears, with his own TRIO build.

Forget reviews, build and LISTEN to the stuff.

Jeff Medwin

BTW, " Ash " taking my prior post's selfie, if anyone wonders, is an Indian-born USA friend of ours. Lowthers.

 

[prem]

Going by your logic, you too have no listening experience of yogibear's system or any of his creations. So how can you say yours is a superior creation?

 

[yogibear]

Jeff, may be your two mentors are descendants of “Audio God”.

My two are simple human beings, two old, retired gentlemen who live tens of thousands of miles apart, both are very respectable in tube amplifier designs and OPT designs and have done great and earned respect from the audio community for their learning and teaching.

One of them recently displayed his “bucket winding skills” done in a jiffy.

And guess what, crazy it may sound, I have a third mentor, just 24 years old chap who unlike many of us here, grew up playing with tubes. We share same scientific curiosity towards music reproduction by tube amplification.

I do agree that a sound low DCR power supply makes an incredible difference to a tube amplifier. But I have my own learning path, all set. And I am an experimentalist by nature and upbringing, I cannot help it. I love what I do in audio. And that matters most.

I hope, apart from audio and tubes, you learn to earn friends rather than alienate them…..

 

[tnvijay]

In my two years experience of winding OPTs, What i have learnt is.. It is no black art. There's lot of patience needed to slowly wind layer by layer with proper interleaving techniques... I honestly agree and accept i haven't listened to Branded OPTs like Tamura etc,But what i hear out of my Handwound OPTs is something I have never listened in any of my solid state amplifiers and I have been building Solid state amps from my late teens.So ,I believe that our ears are the best judge. If it sounds better than my previous amplifier,i consider that I have progressed and learnt something new. And there's always the square wave test... As far as possible,I try to achieve good square wave with reasonably good bandwidth.. And that is all that matters. Remember,by Diy, I spend only a fraction of the money than Buying a OPT. I don't Even believe that super costly cores sound better- Because,We just have to remember Tube OPTs have been designed and built since 1940s and The most famous Tube designs like Williamson originally should have used normal iron cores by that time. It all winds down to how the Winding is done with respect to the Gauss and Efficiency factor. At this juncture I have to express my gratitude to many Diyaudio members,who selflessly share their knowledge without showing any air of superiority..Yvesm in particular who has generously shared with the Diy community a OPT design software which pretty much gives accurate prediction of the expected performance of the OPTs. It needs some mentor to understand. I am fortunate I have one gentleman who like a father figure, patiently taught me... This journey is fun and adventurous and There's no looking back!. So,let's roll our trafos and keep experimenting!!

 

[drlowmu]

By your logic, you too have zero listening experience. You have never heard yogibear system or any of his creations. So what gives you the right to say yours is a superior creation?

"How can I say"?? Maybe due to my experience in audio, over a far greater number of years.

FROM LISTENING EXPERIENCE :

My Father was an audiophile. It starts when I came home from the hospital, after being born. So Prem, from December 1944 on, as my Mother was nursing me, we had an ALTEC LANSING 604 field coil duplex, playing WOR / New York City classical music, as background music to listen to, in our living quarters. So I have high efficiency speakers, high fidelity listening experience from age one week, to age 78 1/6th years.

FROM BUILDING and DESIGN EXPERIENCE :

Pictured a few posts above, is Jeff in 1979, working on a very first triode tube amp build.

And from 1981 to 1982, with the guidance of my first audio mentor ( Robert W. Fulton, 1925-1988 ) I from-scratch co-designed and built my first tube amp. Monoblocks on SIX steel chassis, zero NFB and DOUBLE actively B+ regulated. Mr. Fulton, my first audio mentor, had me TRYing for the " best possible " from my very first build.

How often does anyone see UNDERSIDE photos of a first from-scratch build, in THIS world, executed like so :











Designed / scratch built 1981 and 1982, as my beginner's amp. Ten 6SN7GTBs, into six P-P-P 6B4G triodes.

 

[Christy]

View attachment 74722View attachment 74723

The first amp is 6BM8 Single Ended Pure Class A, 6AX5GT tube rectified, no NFB and makes a clean 1 watts per channel. It’s a fully dual monoblock design under the hood with choke filtered power supply. The output transformers are customized and well mated to the topology and were hand wound in India and have been scope tested as 30hz to 17k frequency response @1 watts with 0.4 % distortion. The output taps are for 8 ohms impedance speakers. The amp drives any full range or 2 way setup at 93dB and above with no dearth of loudness or low end. The OPTs were designed under guidance and blessings of “Bud Purvine Sir”, from US.


View attachment 74724

View attachment 74725

The second amplifier is Mullards 5-10 clone which features EF86 tube at driver stage, 12AX7 for phase inversion and two EL84 in Push Pull mode. The amplifier makes 12 watts per channel and accepts 4 and 8 ohms impedance speakers. Drives anything at and above 89dB.

The amp features finest Push Pull OPT you can lay your hands on, speced at 8hz to 50khz @5 watts, with 0.05% distortion and a perfect phase response. They were hand wound in India using finest material and again under aegis of “Bud Purvine Sir”.

Both the amps were built from scratch with minimal hand tools.

I hope to build more interesting valve amps using some exotic tubes and very interesting topologies including a very fine sounding DHT Tube preamplifier. Will share them as I go forward in my passion…. It’s a journey filled with great fun and learning, de-learning never stops…

Feel free to voice your critical comments…

wow!