So, as a part of my amplifier education in order to property evaluate design and theory, could someone list the other highly esteemed electrical amplification engineers (hopefully on this forum) specifically, those who do not believe in sayyy....Bybee sort if devices so I could have this a point of reference?
http://www.diyaudio.com/forums/solid-state/5107-capacitor-distortion.html
Bi polar caps used correctly ( below 0.4 V ) and NPO are excellent performers . I often use bi polar caps in feedback arms , 1000 uF 16 V can be very useful . They measure pretty good and better than fancy ones . Tants also fail in PSU's .
Bi polar caps used correctly ( below 0.4 V ) and NPO are excellent performers . I often use bi polar caps in feedback arms , 1000 uF 16 V can be very useful . They measure pretty good and better than fancy ones . Tants also fail in PSU's .
JLH is my only choice . The rest fill me with doubt . I am a mechanical engineer with an electrical engineering qualification and electronics endorsement . JLH is my beacon . DTN Williamson also . Mr D Self if he would not blush . Sid Smith was a friend . We mostly only talked pentodes . He told me I must listen to components . He had recently discovered they did sound different . I pretended not to know . The sound as I suspect Scott would say is related to measurements . Sony researched vibration in amps . I am convinced that is something that maters . Costs nothing to make it work better . Sony conjecture as in Esprit was magnetic fields cutting the component legs = EMF . I was slightly there at the Esprit birth .
My old boss said people have a bad quality called " beleive your own BS " . The comment was directed at the industry. As Dvv will tell you I believe no one , especially myself . I am not a cynic despite that .
John Linsley Hood - Wikipedia, the free encyclopedia
I assure you that you don't want to know, I hope my link took you to the picture that I posted. Personally I use nothing but standard 1% MF resistors but I don't like seeing things stated as obvious fact that are not. This is my business for almost 40 years please don't tell me that I'm closed minded if I don't accept resistors and wires as directional. The AD829 was designed by my good buddie Moshe G. we have been through thick and thin for 35 years.
Thanks! I should be clearer though. Leaving out those designers who might be inclined to promote cables and such devices as having audible value, what commercial designs are these no nonsense engineers responsible for? I always thought Hafler was a safe bet, but are there even cleaner no nonsense bets? In other words if one wanted to choose from available used amps on market without resorting to say , Bryston thereby going the safe route substituting money for knowledge, how would one best choose high power amps based on no nonsense integrity and design philosophy? Perhaps this is relavant to a book of design philosophy, albeit a cheeky question
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IMHO, the only truly great Solid State Amp designer was Bob Carver. (Phase Linear, Carver, Sunfire)
The Stereophile article showed what he can do. Always innovative but NEVER innovation for innovation's sake .. only to solve important problems which lesser designers aren't even aware off.
Unfortunately, some of his designs had a tendency to burst into flames 🙂
JLH designs had a similar tendency to burst into flames but without the good sound except for one or two exceptions that prove the rule.
Also worth considering are the last generation of big valve amplifiers from LEAK, Radford, Dynaco, Marantz, McIntosh. These are surprisingly well behaved in comparison with modern stuff and put Solid State stuff like early Crowns to shame. Their designers, some of whom I've had the privilege to work with, sneer at many 'modern' gurus and for good reason.
More difficult to recommend 2nd hand transistor amps except for Bob Carver. eg Dynaco made some awful (early) transistor amps and also some very good ones (their MOSFET designs).
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Thank you. Tube amps are off the short list permanently for many, many reasons. Sadly I sold a Carver 500 to a friend before I decided to chase this down, While I'm not necessarily looking for used amps, I am trying to chase down design philosophy and while I may disagree with Mr. Curl's "Bybee" endorsement and thereby permanently eliminating these amps from my own personal short list, I do understand that toothpaste is hard to put back in the tube. So truly wanting to learn about amplifier design philosophy and it's practical application (duh) This seems like a great place to start and this a useful exercise for any engineer to witness. Helping me with my amp newbie questions should at least make some hard things to understand a bit easier. I have for example, always counted on old Haflers as being beyond reproach, on the super safe side of not throwing money down a "cable" type rat hole. Am I treading on the bullsshiit line or is there truly a real world measurable (I will make a line here in my head) repeatable "safer" zone for ultra low distortion and high power design philosophy?
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Carvers burst into flames amps sound to a person such as I, a great trade off if all else is superb, as that can be safety-ed by myself. (Please assume I can do that Fire Marshall Bill's of the universe). Sounds like great eBay built in bias bargaining leverage if they truly are superb.
I'll take your word for it in general, but I'd still like to see the schematics. I can't help it, I ALWAYS want to see the schematics.
Same here, standard 1%, with 0.5% sometimes, and in select places only if I'm trying to make it sort of a precision circuit. About once in 5 years or so. The only problem I have with that is that my local market is highly polluted with Chinese low, low end products which deviate more than 1%, but even they are fine for development work, but final form uses German made resistors, which do better to much better than advertised.
I have seen a few wires which were "directional", but I admit that directional resistors are a new one for me. What's next, directional PC boards? My advice to the proponents of such ideas is to breathe directionally, strictly exhaling.
Please tell your friend Moshe "shalom" from me - I mean it. He sure has made me happy, just as AD has never once let me down for the last 40+ years. That's "happy" even by AD standards. I just love that chip, easily the best all rounder I have ever come across.
Nige, John Linsley Hood is no doubt one of the legends, The best/worst part is that while in tghe UK, I lived about 16 miles from Taunton (good), but never got the chance to meet him (bad).
He was hyperactive in the late 60ies and early 70ies, and I can't help admiring his good common sense and judgement. Not everybody can do that.
As for Bob Carver, I have no doubt he is a very smart man, but unfortunately, his products, from Phase Linear days, have always suffered from serious economic compromises in production. Call me a freak, but I seriously cannot see a nominally rated 150 WRMS per side amp being fed by two 6,800 uF caps as barely sufficient.
My point is, he tended to save money where he shouldn't have. A friend owned one of his Phase Linear amps, so I know how it sounded "as is", and how much better it sounded when two 22,000 uF milk bottles replaced those 6,800 uF small guys - a whole new story.
I can't help feeling that Bob could have done so much more, if he only did more production engineering and less self-advertising.
He was hyperactive in the late 60ies and early 70ies, and I can't help admiring his good common sense and judgement. Not everybody can do that.
As for Bob Carver, I have no doubt he is a very smart man, but unfortunately, his products, from Phase Linear days, have always suffered from serious economic compromises in production. Call me a freak, but I seriously cannot see a nominally rated 150 WRMS per side amp being fed by two 6,800 uF caps as barely sufficient.
My point is, he tended to save money where he shouldn't have. A friend owned one of his Phase Linear amps, so I know how it sounded "as is", and how much better it sounded when two 22,000 uF milk bottles replaced those 6,800 uF small guys - a whole new story.
I can't help feeling that Bob could have done so much more, if he only did more production engineering and less self-advertising.
JLH is so often refereed to by others . Others who probably overshadowed him . Somehow he escaped any censure for his " good enough " approach . His modesty came across and won hearts I feel . His logic usually impeccable . I beleive Oscar Wilde said someone was a modest man because he had much to be modest about . It is very clever but hurtful . Another member of the Q ? Good manners maketh man ?
Dvv . Did you see the RA 53 thermistor was made in Somerset by Bowthorpe ? I had Irish Cider last night at our local rock festival ( girlfriends boy playing ) . Manders is all they had . The bands very Radiohead as I suppose they would be , the drummer of Radioheads dad makes the Gold disks we see . I walked with him and his dog in Dorcester on Thames . Pure accident he bought the business . Pure accident I met him also .
Dvv . Did you see the RA 53 thermistor was made in Somerset by Bowthorpe ? I had Irish Cider last night at our local rock festival ( girlfriends boy playing ) . Manders is all they had . The bands very Radiohead as I suppose they would be , the drummer of Radioheads dad makes the Gold disks we see . I walked with him and his dog in Dorcester on Thames . Pure accident he bought the business . Pure accident I met him also .
Hafler hired people like Jim Bongiorno and Erno Borbely to do his designing. The name on an amp has only weak or no correlation to the designer's name 😉
Read about Erno & Hafler here.
Double input stages do not seem very promising.
Evolutions of the Hitachi structure (differential input + differential VAS loaded by a current mirror) seem to be able to provide high PSRR and very low distortion at the expense of a slight reduction of the output swing.
The first time I saw the simplified circuit of op-amp OPA627 which is on this basis I immediately guessed it had excellent performances and this was confirmed later.
Samuel Groner presented something quite similar in his document commenting your book on power amplifiers, page #48 figure #56.
(for those who don't know it yet :
http://www.sg-acoustics.ch/analogue_audio/power_amplifiers/pdf/audio_power_amp_design_comments.pdf )
It certainly inspired this product with impressive specifications :
Weiss :: High End : OEM
***
Maybe just a curiosity but I found the following schematic of a push-pull cascoded voltage gain stage for cathode-ray-tubes, it was presented by Peter Bismire of Motorola. I am not sure it would be applicable to audio but there is some matter to think for people seeking the highest slew-rates : 3900 V/µS !
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That is nearly always so . I go around hearing of designs . When I say who designed it they give a name I know to be untrue . Many designers are never given the spotlight . In my company I actively discourage my name being used .
Loricraft audio is different . My friend , I helped him ( still do ) . I didn't design the 501 I just was allowed to make a special 301 . Richard Duffin at the Dept of Engineering Oxford also , he was my J B I trusted . Richard I am certain could do anything asked in mechanical engineering and has the resources . He is a hi fi nut , I am sure he has never been seen as a designer ? Scott motorcycles also is his specialty .
Love the dia above in # 1854 . I have had my greatest success as a mechanical engineer . I have not one piece of paper to say I am one . I have even done degree level projects in it and got good results from students thought to be struggling . All of my projects were real and I was desperate for data . I rejected going for patent on one . I noticed my enhanced turbo charger is now real . That is to combine it with induction motor core ( centre shaft ) . Mega-charger was my name for it ( 1997 , never published ) .
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The reverse is also true, look what they made out of Ken Ishiwata (sp?) at Kenwood I believe it is.
jan
jan
Sid Smith was no fan . Airbrushed out of history when the Model 9 was reinvented . " K I doesn't speak to me as my old boss reminded him of Sid . All Sid said was why didn't they contact me ? I could have helped " . Sid wanted me and him make 9's again . He died about 3 months later from cancer that was then undetected .
I have to tell the Q . You may never own an amp as good as that . I had to loose my prejudices on hearing one . Sid was a gentlemen . I made a friend of him by steadfastly saying pentodes are better . When he understood me he agreed and said EL 34 his favourite triode if you get my drift .
What did they do, Jan? A link, perhaps?
What's Kenwood/Trio got to do with THE Marantz spokesperson is what befuddles me?
Regarding outside design, one has only to think back to Philips' Black Tulip series 1979-1982. A hodge-podge, typical of big companies wanting to talk only with other big companies.
The tape deck 4520 (which I owned 1981-1998) was an original Philips product, actually manufactured in Philips' tape deck factory in Austria. The passive and active speakers were made in Philips' speaker factory in Belgium.
But the tuner (22AH180), the preamp (22AH280) and the two power amps (22AH370 and 22AH380, 2x60 and 2x100 W respectively) were not only made, but also in all probability also designed in Japan. I venture to guess that the OEM was Hitachi, given that most semiconductors inside are from Hitachi. Also, Hitachi's full name is Hitachi Heavy Industries, so I suspect they could also do the superlative mechanics at a price few could match.
At the time, of course, most German companies were doing the same - for example, the mammoth BASF had its stereo manufactured by Luxman, Uher by H/K (who bought them lock, stock and barrel), etc.
So, if the BIG guns do it, why not the smaller ones as well?
So lots of begrudging point given to Bob Carver. Throw some bigger filter caps in and go to town with the best around?
Like I said, nothing to do with knowledge or design prowess, just purely economic compromises.
Don't you think two 6,800 uF caps are a bit small for a nominally 2x150 WRMS POWER amp?
Throw in bigger caps and the sound improves - as it always does when you do that, with everybody.
I could have mentioned his quasi-complementary, all NPN designs, but truth be told, I have heard some very good amps using the same and a lot of not so good amps, even if they did use fully complementary output stage topology.
My own Philips 370 power amp, rated at 2x60 WRMS/8 Ohms, used 2x6,800 uF caps. But its somewhar bigger brother, the 380, rated at 100 WRMS/8 Ohms, uses 4x22,000 uF caps. I took oput the two 6,800 caps and installed two 12,000 uF/71V Gold Tune caps with rather obvious sonic advantages. True, I did throw out 32 year old caps and installed brand new ones, that in itself will bring clear benefits, but still, size does matter.
My H/K Citation 24 power amp, their top of the line Citation series, also used 6,800 uF caps, however 2+2 of them in a dual mono construction, and admittedly, they do squeeze some prodigious impulse power levels into low impedances, but that too sounded better when the old caps (from 1997 or so) were swapped for new 10,000 uF German made caps. Impulse power levels were now limited by PSU rails only, and that's as good as it gets. Not that I'll ever need them ...
My H/K 680 integrated amp from 1998, rated at 85 WRMS/8 Ohms uses four 8,200 uF.
And these were regular production models, not supposedly the High End as Phase Linear pretended to be.
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