...and I'll add a third.
I'm somewhat of a "lurker" on this forum, but I've never failed to receive a positive, helpful response on those occasions when I have posted a reasonable question (or even a stupid one, for that matter). It has also never escaped me that what to do with any advice I receive is my decision alone.
Most of those who contribute to this forum have forgotten more than I'll ever learn about vacuum tube electronics, and I for one am most grateful for their collective willingness to share their time, effort and wisdom.
Thank you all!
Those of us who were brought up in the 1950's HAM radio era (myself) Radio TV repairs & Mil service; had no option. It was tubes/valves only. We had to learn it and is the most invigorating diverse subject from chassis build (mechanics) and maths & physics. I am one of those from that era when every surplus store had piles of WW2 surplus. It was so easy and the kudos was different with a room in the house set aside as Dad's room or the lab with a long short wave aerial down the garden. The slide rule was the day and Moon travel couldn't be done without this sliding tool and I still use it.
We are here to carry on with this fascination. I hate the word Vintage radio it seems too narrow, I much prefer Heritage electronics it carries more fame and dimension. I suppose as a driver and fireman of steam trains I tend to associate the same; Heritage railways one sees people flock like wasps to jam in numbers never seen before, to witness smell the coal, steam and hot oil of yesterday. Kids and adults love it and ones see it on the faces. As with old electronics, the smell of old settled dust is also akin.
There is nothing so satisfying than doing mature education.
richy
We are here to carry on with this fascination. I hate the word Vintage radio it seems too narrow, I much prefer Heritage electronics it carries more fame and dimension. I suppose as a driver and fireman of steam trains I tend to associate the same; Heritage railways one sees people flock like wasps to jam in numbers never seen before, to witness smell the coal, steam and hot oil of yesterday. Kids and adults love it and ones see it on the faces. As with old electronics, the smell of old settled dust is also akin.
There is nothing so satisfying than doing mature education.
richy
What you say makes absolute sense..
Sounds like you had some fun at least with the bikes.. I'm probably on some sort of plateau myself, as for several decades I was adamant that SE couldn't be that good, finally plucked up the courage to try my hand at one and was surprised..Never looked back, now and again wonder if I should have.. Probably time to go back and do something PP and prove once again that it is all about the design.. 
My tube design activity started in 1972, when I put together my first guitar amp. I took transformers from stock TU-50 PA amp that used GU-807 tubes (you know, they are 6L6 type tubes), and sounded nasty: a little bit higher quiescent current, and plates are red, so output tubes were under-biased. Also, output transformer was wound for 30 and 120V outputs, it's quality was low, so I rewound it by hand watching TV. It was interleaved, for 8 Ohm output.
The power tranny was a bit rewound, I needed 12.6V for GU-50 filaments.
First phase splitter was Concertina, but I found that it can't drive output tubes properly, so added a long (actually, not so long) tail pair (6N6P), actually making Williamson style amp, but I did not know about Williamson then. So, an output stage had one 6N2P tube (common cathode + Concertina), LTP driver on 6N6P, and a pair of GU-50. Preamp had a single 6J32P (like EF86). The gain was too high, but I could not get it lower: increased feedback caused VLF oscillations, with blue light winking in output tubes. I was a 7-th grade student then, and did not know about phase shifts, stability, etc... All my knowledge were from schoolbooks and popular magazines that I studied carefully learning what people do, but sometimes not understanding why they do that. How would I describe that amp? It sounded TASTY!
It was my 2'nd amp, the previous one was transistor one, with 4W output. Sound of that guitar amp was gorgeous!
Later, in University, I believed that transistors are the way to go, and tried to design an amp that is as clean as possible. I knew then much more, starting from physics of semiconductors and other EE stuff I was still learning. I designed and built fully symmetrical amps with complementary diffpairs, but my 200W amps with very low THD measurements, regulated PS, oversized power trannies made on an iron from 1-2 KW variacs, lots of filter capacitance, almost zero output rezistance, could not compete with stock tube amp, MONO-130 made by Tesla. Checho-Slovakian amp measured bad, but sounded TASTY! It was very disappointing...
Later, thinking as if I am cheating in order to simplify schematic and create so-so linear function from 3 parts, I made class A+C amp for bass guitar. And it sounded like a tube amp! I won't believe that... An amp with zero bias output stage sounded better than properly biased output stages! Again, it sounded TASTY!
Actually, I had all information then, including rich experience of creating of different types of distortions making analog synthesizers and guitar effects... But it took YEARS to digest all information and experience I had, and finally SCREW that beliefs about THD, voltage amplification, dumping factors, and other similar things...
The power tranny was a bit rewound, I needed 12.6V for GU-50 filaments.
First phase splitter was Concertina, but I found that it can't drive output tubes properly, so added a long (actually, not so long) tail pair (6N6P), actually making Williamson style amp, but I did not know about Williamson then. So, an output stage had one 6N2P tube (common cathode + Concertina), LTP driver on 6N6P, and a pair of GU-50. Preamp had a single 6J32P (like EF86). The gain was too high, but I could not get it lower: increased feedback caused VLF oscillations, with blue light winking in output tubes. I was a 7-th grade student then, and did not know about phase shifts, stability, etc... All my knowledge were from schoolbooks and popular magazines that I studied carefully learning what people do, but sometimes not understanding why they do that. How would I describe that amp? It sounded TASTY!
It was my 2'nd amp, the previous one was transistor one, with 4W output. Sound of that guitar amp was gorgeous!
Later, in University, I believed that transistors are the way to go, and tried to design an amp that is as clean as possible. I knew then much more, starting from physics of semiconductors and other EE stuff I was still learning. I designed and built fully symmetrical amps with complementary diffpairs, but my 200W amps with very low THD measurements, regulated PS, oversized power trannies made on an iron from 1-2 KW variacs, lots of filter capacitance, almost zero output rezistance, could not compete with stock tube amp, MONO-130 made by Tesla. Checho-Slovakian amp measured bad, but sounded TASTY! It was very disappointing...
Later, thinking as if I am cheating in order to simplify schematic and create so-so linear function from 3 parts, I made class A+C amp for bass guitar. And it sounded like a tube amp! I won't believe that... An amp with zero bias output stage sounded better than properly biased output stages! Again, it sounded TASTY!
Actually, I had all information then, including rich experience of creating of different types of distortions making analog synthesizers and guitar effects... But it took YEARS to digest all information and experience I had, and finally SCREW that beliefs about THD, voltage amplification, dumping factors, and other similar things...
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.