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Old 1st November 2006, 08:53 PM   #21
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He's back on AA with a vengeance!
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Old 2nd November 2006, 02:14 AM   #22
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I met both Jeff and Dennis at RMAF. Both seemed to be very pleasant gentlemen. In fact, I also got to hear Dennis' 2A3 amps. Probably the best I've come across so far.

Dennis is a little on the whacky side when he's trying to explain circuits. Let's just say he takes a little different approach than most of us (you should ask him about the relationship between cows and amps). Hey, you can do math all day, but in the end it's the results that count.

Anyway, what might come across as gruff, intolerant, or arrogant in one of these forums has a entirely different appeal is person.

jh

PS - I don't do the low dcr thing. I design for critical stability, which requires an optimum and finite value for dcr.
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Old 2nd November 2006, 02:32 AM   #23
jarthel is offline jarthel  Australia
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Originally posted by hagtech


Anyway, what might come across as gruff, intolerant, or arrogant in one of these forums has a entirely different appeal is person.


some people acts differently in real life than their internet personas. just that forum members see the internet persona so they assume people are like that in real life as well.
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Old 2nd November 2006, 02:38 AM   #24
Tweeker is offline Tweeker  United States
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I like low DCR, I just question low DCR + low capacitance PSU, it sounds like a recipe for ringing.
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Old 2nd November 2006, 06:03 AM   #25
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IMHO, while it is may be possible to make a low DCR, low inductance and low capacitance PSU work, that doesn't mean it's a good idea. I suspect it needs a lot of tuning and would probably be quite critical. If any of the amplifier design conditions were to change, like the voltage or current draw, then the PSU would probably have to be re-tuned. Sounds like a lot of hassle and grief for no obvious tangible benefit.
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Old 2nd November 2006, 06:17 AM   #26
Tweeker is offline Tweeker  United States
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Sounds like a lot of hassle and grief for no obvious tangible benefit.
When did that ever stop a true believer? Part of why I think these supplies are apparently working ok is that they are going into class A amps that are seldom overloaded, few supply transients.


A smaller cap may drain its (smaller) charge faster, but its the caps impedance we care about, is it not? If a bigger cap happens to manage having both lower ESR and ESL, should it not be 'better'?
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Old 2nd November 2006, 06:32 AM   #27
rdf is offline rdf  Canada
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Check back in at AA. Henry Pasternak, the approach's most vocal and technically capable critic, has returned under various pseudonyms, now in agreement with its validity and trying to work out the underlying theory. It appears to be a viable and valid PS topology. Don't shoot the baby with the messenger!
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Old 2nd November 2006, 10:56 AM   #28
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It appears to be a viable and valid PS topology.
I daresay it is but I also get the impression, from various people's contributions to the discussion, that it needs to be optimised. As I said before, I fail to see any obvious benefit of the approach to justify either the hassle of making it work or the thousands of words that were spent arguing about it on AA.

When Jeff Medwin only preached 'low DCR', most people agreed with him, myself included. It was patently obvious that excessive DCR in iron components was detrimental to regulation. He was preaching to the converted and that should have been the end of the argument but it didn't seem to satisfy Jeff. He had to have his say anyway and he rubbed a few people up the wrong way in the process with his overbearing attitude, including Henry Pasternak.

Later, when Jeff got onto the 'low inductance, low capacitance' kick, he had some difficulty selling it, perhaps because it wasn't his original idea. It seems to have come from Dennis Fraker and Jeff found he couldn't defend it convincingly. Dennis's contributions didn't help, because he was patronising and talked in riddles.
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Old 2nd November 2006, 01:43 PM   #29
jlsem is offline jlsem  United States
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I met both Jeff and Dennis at RMAF. Both seemed to be very pleasant gentlemen. In fact, I also got to hear Dennis' 2A3 amps. Probably the best I've come across so far.
Those guys were pretty goofy, but I personally wouldn't go as far as saying their system was wonderful, although it is very difficult to tell under show circumstances. The best sounds I heard at the show were of conventional design but highly developed, usually driving speakers that were way out of my price range.

The problem with Medwin on AA is he writes as though these amps are a second coming and anyone who won't agree has bad hearing. There were a lot of rooms at that show that if anyone thought they were any good, I'd question their hearing.

I personally use the lowest DCR power transformers and chokes I can reasonably get and agree with his philosophy in that regard. But that rant about the G2 supply and that big high current choke being able to provide good regulation was bizarre.

John
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Old 2nd November 2006, 05:36 PM   #30
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wouldn't go as far as saying their system was wonderful
That could be, I never got to hear their room. My exposure to the amps was after-hours in a shootout (in the Galibier room). Even up against my own 2A3 design (prototype). A new Quicksilver design also fared well. This was also my chance to finally hear a top-end digital amp. Oh my, it was like AM radio in comparison. Really bad.

jh
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