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Old 5th July 2008, 02:11 PM   #11
snoopy is offline snoopy  Australia
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Quote:
Originally posted by stoolpigeon
snoopy, there will be many Naim amps running long after all that Japanese rubbish you refer to has been thrown in the bin (if it hasn't already).

sp
The Japs were using advanced power semiconductor devices decades before Naim ever did The proof is in the eating of the pudding. See how many of those so called rubbish "Japanese" designs are snapped on ebay these days and then see how much demand there is for old Naim amps. Naim doesn't even get into the starting gate anymore

Paying big dollars for a quasi complimentary output stage using mediocre semiconductor devices LOL It's comical really

There is a sucker born every minute in the HiFi fraternity and the ones that bought Naim got taken for one hell of a ride Sorry to break the bad news to you
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Old 5th July 2008, 02:15 PM   #12
snoopy is offline snoopy  Australia
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Originally posted by janneman


The 'secret' of using quasi-complementaries because NPN's have better SOA has never been a secret to anyone half-witted about audio design.

Naims may have been SOTA half a century ago. Two weeks ago I attended a Naim demo at the local hifi club. The week after I demo-ed my 'diy' amp. 28 out of 30 attendants stated that after the Naim demo, it was good to hear some good equipment again.
Maybe you should review your standards, John.

Jan Didden
Well it makes you wonder what standards John actually uses to evaluate audio equipment if he is willing to jump in with the Naim camp
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Old 5th July 2008, 03:40 PM   #13
bappe is offline bappe  Sweden
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Default What is the problem with Quasi-complementary?

This have nothing to do with the Blowtortch but here it goes.

Have mostly been reading on this thread but i think i need to defend the quasi-complementary design a bit. First of all Snoopy, are you mostly dismissing QP because of its age and theoretical shortcommings? On paper it might not look so hot but in practice it can be realy good, both tecnically and above all, sonically. I urge everyone who have never heard an old Dynaco st-120 with some bias on the output stage on a pair of not to power hungry speakers to give it a listen. It is a bit rough around the edges if you push it but it has a drive and dynamic flow that really gets me going. I am not saying it is the best amp i have heard (far from it) but it certanly beats alot of modern amps.

BR and thanks for charing JC!

Anders
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Old 5th July 2008, 04:13 PM   #14
snoopy is offline snoopy  Australia
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Originally posted by john curl
I think that the devices were German. Probably Siemens.
The other problem with that Naim amp I saw once is that it kept cutting out when it got to hot because they didn't put enough heatsink on the output devices and rather they were relying on the inefficient design of the case to act as a heatsink

Not a good design I'm afraid
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Old 5th July 2008, 04:18 PM   #15
snoopy is offline snoopy  Australia
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Default Re: What is the problem with Quasi-complementary?

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Originally posted by bappe
This have nothing to do with the Blowtortch but here it goes.

Have mostly been reading on this thread but i think i need to defend the quasi-complementary design a bit. First of all Snoopy, are you mostly dismissing QP because of its age and theoretical shortcommings? On paper it might not look so hot but in practice it can be realy good, both tecnically and above all, sonically. I urge everyone who have never heard an old Dynaco st-120 with some bias on the output stage on a pair of not to power hungry speakers to give it a listen. It is a bit rough around the edges if you push it but it has a drive and dynamic flow that really gets me going. I am not saying it is the best amp i have heard (far from it) but it certanly beats alot of modern amps.

BR and thanks for charing JC!

Anders
No I'm dismissing it because with modern semiconductor devices it is no longer necessary or desirable to resort to this asymmetrical design practice.

I can understand your sentimental attachment to this old amp but can you please explain why you think it is better than most modern amps ??
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Old 5th July 2008, 04:35 PM   #16
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Who said that the Naim power amp is better than many newer power amps? Julian has been dead for about 10 years, Naim is just another company now. However, it its day, Julian did some innovative things, like provide high peak current, not put in E-I protection, keep the circuit through-path simple, REMOVING the output coil, etc. He was very successful, as most POWERFUL amps at the time were quasi-comp. I worked on one, myself, in 1973, because only NPN power devices had enough safe area at that time. In order to get around that problem and use complementary output devices, we had to use more complex circuits, such as series connection (Borbely), or bridge connection (Gale) to REDUCE the working voltage across each output device, or else use constricting E-I protection, or both.
Crown and Phase Linear used quasi-comp in the '70's. Marantz and JBL used lower power, or multiple CHERRY PICKED complementary output devices, that the rest of us could not get, and often severe E-i protection.
If you can find a Marantz 500, go for it, but we found it compromised, sonically, as we did Phase Linear, and most other solid state amps at the time.
Now, what about the sound of Naim? I visited Julian at his home in 1976, and spent a few days. He was very proud of his hi fi system and demo'ed it with a popular song that included a chime like door bell. I told him that it did 'door bells' as good as any hi fi that I ever heard, but that other aspects could still use improvement. As you see, I am an 'equal opportunity' critic, and don't just criticize the rest of you.
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Old 5th July 2008, 04:49 PM   #17
bappe is offline bappe  Sweden
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Default Re: Re: What is the problem with Quasi-complementary?

Quote:
Originally posted by snoopy


I can understand your sentimental attachment to this old amp but can you please explain why you think it is better than most modern amps ??

I tend to play music through it, if it did not do that in a way that i can tolerate it would go out the door asap. I am not saying that it is a superior topology, just that one can make a darn good amp with either technology, there is so much more to amp design than just the choice of basic topology. My line, dac I/V and riaa today are symmetrical designs, not JC but much inspired by his designs. For power i use a circlotron, hence symmetrical but not complementary.

BR,
Anders
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Old 5th July 2008, 04:52 PM   #18
snoopy is offline snoopy  Australia
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Originally posted by john curl
Who said that the Naim power amp is better than many newer power amps? Julian has been dead for about 10 years, Naim is just another company now. However, it its day, Julian did some innovative things, like provide high peak current, not put in E-I protection, keep the circuit through-path simple, REMOVING the output coil, etc. He was very successful, as most POWERFUL amps at the time were quasi-comp. I worked on one, myself, in 1973, because only NPN power devices had enough safe area at that time. In order to get around that problem and use complementary output devices, we had to use more complex circuits, such as series connection (Borbely), or bridge connection (Gale) to REDUCE the working voltage across each output device, or else use constricting E-I protection, or both.
For crying out a loud John, all of these so called "innovative" things made it an unreliable product and ready to blow up at a drop of a hat which it did in a lot of cases

Any of the other manufacturers could have remove the same elements from their design and made them an equally unreliable product. I wouldn't have called it innovative to make a product unreliable like that
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Old 5th July 2008, 04:56 PM   #19
snoopy is offline snoopy  Australia
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Default Re: Re: Re: What is the problem with Quasi-complementary?

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Originally posted by bappe



I tend to play music through it, if it did not do that in a way that i can tolerate it would go out the door asap. I am not saying that it is a superior topology, just that one can make a darn good amp with either technology, there is so much more to amp design than just the choice of basic topology. My line, dac I/V and riaa today are symmetrical designs, not JC but much inspired by his designs. For power i use a circlotron, hence symmetrical but not complementary.

BR,
Anders
Rather than offer your subjective opinion can you answer the question why you think this design topology is better than most new amplifier designs ??
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Old 5th July 2008, 05:03 PM   #20
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It is NOT the topology that Naim uses, but the way that it is implemented. You know, no E-I protection, no output coil, etc. Yes, it makes it non-bulletproof. Julian owned the company, so he only had to answer to himself, and this gave him a sonic advantage. Can't you understand that what a lowly engineer must do to protect himself from being fired, IF something goes wrong with an amp, and he only had to restrict the peak current, and add a output coil, to remove the potential problem? Julian went for 'sound' first, absolute reliability second. Much like Lotus made race cars. Julian used to race cars, so maybe that is where he got that approach.
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