dowto1000
BANNED
Kevin,
I apologize if I divert the discussion a tiny bit, but I would like to ask Dowto to expand on his statement about PSU.
Dowto100, you've stated on several occasions (in this and other threads) that PSU is critical for SE amp, and I fully agree with you on that. But what does it mean (for you) to build a "high-quality" PSU? Can you list a "full" set of specifications? And how do you determine/measure the performance of your PSU as it relates to the amp performance? Are these measurement objective and quantitative (i.e. done with the scope/analyzer and can be plugged in to Excel for analysis or graphing), or are they subjective and based on the listening tests? BTW, I either way is fine with me, please don't take my questions as insult or challenge, but rather as a learning/sharing inquiry.
Sincerely, Paul.
Hi,
Good question. Personal Background.
My first audio mentor was Robert W. Fulton, of Fulton Musical Industries . He was responsible for the FMI-80, FMI J-Modular, Premiere speakers ( 12HZ to 100 kHZ ) . I first met RWF in 1978, and in 1981, I built my first DHT amp, 2A3 P-P, from an AudioNote Kit for Audio and LP Reviewer Neil G. Levinson. In 1982, I decided to do my own design. The very first thing RWF told me was " to make all the chokes to the 2A3 Finals 20 Ohms or less, IF I can find them. " He also suggested two L/C sections in series, as being superior. A six chassis 700 pound monster evolved, 1982-1986 .....P-P-P 6B4Gs.
Sadly, RWF died in 1988, and pre-internet, I corresponded with other amateur audio designers and DIYers, People like Art Loesch, Herb Reichert, JC Morrison, Jim Dowdy, and Dennis Fraker. I shared freely with them " 20 Ohms or less " on Ls.
Reichert's Flesh and Blood 300B amp had my "only $8.00 surplus - priced potted 3 HY at 24 Ohms DCR choke ", as part of his final design in that Sound Practices magazine article.
Dennis Fraker introduced me to a PhD EE - audiophile, who was head of the EE Department at the University of Alabama. Dr. Charles E. Halijac gave me a scholarly run down on DCRs in power supplies, and how conventional EE supply designs " by the book " were " outmoded and out-to-lunch ", something I already sorta knew, and it alluded to RWF's " 20 Ohms or less ".
I think, in around 1998, Dennus Fraker, who was my brightest and best audio friend, and a " second audio mentor", developed his first Serious Stereo DC 2A3 SE audio amp. It used two 10 Ohm C-2708 Stancors, and two L/Cs, ....right up my alley. But Dennis' implementation was FAR FAR advanced, from just using Low DCR Chokes. He also BEAUTIFULLY devised a scheme where the chokes and the amount of capacitance, in uFs, was also low. This was HIS own LSES supply, totally unique in the history of audio. LSES stands for Low Stored Energy Supply.
From Dennis' second year showing at RMAF / Denver, 2006, I attended those shows annually, to hear his SE 2A3 amp implementations, and anything else that sounded good to me, in audio. Fun. I applied his approach to my SE amps, and enjoyed unique results. When I A-Bed my SE 45 amp, with LSES, against, say, a local audio friend's Yamomoto A-08, my implementation put that Yamamoto SE 45 amp to TOTAL shame !! We both heard it instantly, we KNEW, and we were encouraged.
I eventually wanted to share this supply , based on a MONO 45 or 2A3 amp, with good people on the Audio Asylum. There, I had mixed results. The " 100 year old textbook theory guys, " ALL of them never EVER hearing Dennis' amps at a RMAF show, wanted to criticise me for parting with their beloved theory of " critical inductance ". Two very very sharp EEs, Messers John L. Hasquin, and John Swenson, embraced the design concept, developed solid engineering theory to explain why it was so good, and developed their OWN version of LSES, called by Swenson, a FLYWHEEL. These two actually built a circuit and LISTENED to what they built...amazing !! If anyone wants to read their chronological AA Posts, I have them saved and can email them to you.
I did try Swenson's Flywheel , ( which used Fraker's design concepts in different way ), and eventually, I personally went back to pure LSES, ala Dennis, - upon HEARING his RMAF exhibits annually, and have stayed there, and its been developed additionally, in subtle ways.
So, ALL OF THE ABOVE, represents 37 years of my DIY audio life, dedicated to this subject ( 2018-1981) .
In a separate post, I will address your questions, on HOW I would employ LSES in 2018, and what constitutes a good SE amp power supply, in my experience. This post, addressed my personal background for folks to comprehend.
Have fun, I always do.
'Am presently prototyping a SE two stage Direct Coupled 6AQ5 amp, ultralinear. That tube itself, deserves a great circuit implementation, IMHO.
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