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In Reply to: RE: Sorry, it was caps not resistors, here: posted by gusser on March 19, 2012 at 10:02:49
And it is very audible on high efficiency speakers. Rk bypassing, almost everyone screws it up. Others have attempted it, and sorta half a**ed it, but ONLY Dennis Fraker, in 1989, had it down to a "tee". I hear it in all his amps when I listen at RMAF, assuming his digital source is clean, which is not always the case.
I'll stand 100% by that early post.
If you think about it, you may deduce why this is so Gusser. Listening to it is the way it is done, not with osillyscopes can one get it, nor with spectrum analyzers.
A film cap may measure flat, with simplified sinusoidal sources, but not play back flat under dynamic / music conditions. Different values, and different manufacturers caps, play back different parts of the audio spectrum, as heard at the speaker voice coil.
Nasty to contemplate isn't it !! That is OK, Dennis did the heavy lifting with this. ONLY Dennis did this correct in my experience. Kudos to him, that is just ONE reason why he gets my support.
Jeff Medwin
Follow Ups:
this whole idea about multiple bypass capacitors and what they do has a very low transfer efficiency into my belief system.
Hi Lew,
It would be readily audible on high efficiency speakers, when doing all film bypassing.
From what I understand, it takes a minimum of five different values to get it REALLY optimized, which so far, only Dennis Fraker, in 1989 no less, knew how to do. Also amazing to me was his development of LSES or a modern power supply WAY back then, also found in the original 1989 Serious Stereo 2A3 amp.
Myself and a few other amateurs are working on learning this bypassing topic in 2012. It takes good LISTENING on a GOOD high efficiency audio system, and a big pocket-book to do right.
Read the article on the two stage DC SE stereo amp by the two Italian audiophiles in Sound Practices, about 1994 as I recall, re: Rk bypassing. They used three caps on each Rk, a film-only main cap, bypassed with a .22 PIO, bypassed with a .01 uF Silver Mica, three in parallel, LONG time ago. Its there, in print Lew.
I write this to you as "my" side of the topic. Do and think as you would like to, I have no big problem with you doing that.
Jeff Medwin
I have no doubt that Dennis may have found a potion of 5 different capacitors that made HIM happy, listening to his chosen sources and driving his particular set of speakers using his amplifiers. In fact, I stand in awe of his patience and perseverance. But I think you over-state the significance. There is no general conclusion to be drawn from this story. It's just an interesting anecdote. It's not solid data, even in this touchy feely subjective audio universe.
Every time you add a capacitor, you have to take the bad with the good. You cannot say you are using capacitor X because it does a great job on female vocals and capacitor Y because it does a great job on male vocals, and, by gum, when you parallel them both, you get an amplifier that sounds fabulous on male and female vocals. That might happen, but it's a happy accident. It is equally likely that you will get an amplifier that sounds like shit on vocals.
Have you ever used multiple value DynamiCaps? They can parallel without a lot of the conventional problems you experienced and allude to in your post, according to Dennis.
Jeff Medwin
Jeff, I like reading your posts.
I do have to ask, what happened to Dennis F in 1989? Did he get hit by lightening or run over by a farm implement? There seems to have been an epiphany in that year for Mr F. with all things solved at once. You have mentioned a few things that Dennis realized / discovered at that time.
As I understand it, here is my take :
Dennis told me he used to just modify amps, McIntosh 60s, MI-200s, and he had a pretty good reputation then with AudioMart people.
Some person gave Dennis $40,000 to develop a SE amp, and over two years, he came up with the Serious Stereo 2A3, his first-ever total amp design and build. He made four monoblocks, which I can see have hardly changed at all since then.
Film caps would go out of production, and wiring choices got better (Siltech), but Dennis thoughtfully engineered it from the start, optimized the design, so he has only made minor changes over the years.
The basis for the LSES supply came about as he and Dr. Charles Halijak, E.E. PhD. did amplifier mods. These two audiophiles used to get winders to copy the Citation 2 choke, and noticing that smaller chokes worked better, Dennis simply greatly refined the concept.
He is an unusual bird. Always honest. It is a fact he has spent several fortunes owning Hi Fi equipment. Never married, he has owned two good movie theatres, and a movie theatre service company. Besides being trained as a technician (electronics) in the Coast Guard, and working in mines, Dennis worked for Montana Power and many in-the-field / head electrical engineer positions, plus oil refineries with his Dad. Hey, that was Montana, go where the work is.
Jeff
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