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Old 5th July 2008, 11:08 PM   #31
VivaVee is offline VivaVee  New Zealand
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Default NAIM design

The original Naim power amplifiers used BDY56 output transistors. These had an fT of 10MHz when the competition (such as NAD3020) were still using 2N3055 with fT of 1MHz in a quasi-comp configuration.

The complementary output pairs available and used in the high power amplifiers at the time were MJ15003/4 which had an fT of 2MHz.

The quasi-comp configuration ensured that the low frequency transistor matching was excellent and real. As opposed to the theoretical matching of a complementary npn/pnp pairing.

The transistors used in the input long tail pair were BC239C. These were high fT, low noise PNP transistors compared to the slower noisier NPN transistors normally used.

And the list goes on with respect to the component choices for the VAS and driver transistors.

I would not recommend building one today but you can learn a good deal from examining and UNDERSTANDING the circuits that Julian Vereker used. Especially,but not necessarily, if you are prepared to put it in historical context.
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Old 5th July 2008, 11:53 PM   #32
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What year did the 15003/4 type come into being? 1986?

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Old 6th July 2008, 01:11 AM   #33
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BDY56 looks like the right part. 10MHz Ft vs 2MHz Ft that I was using at the time.
MJ15003/4 came out in 1975 or so.
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Old 6th July 2008, 03:46 AM   #34
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Originally posted by john curl
Jan, AT THE TIME, that Julian made the decision to leave out the coil, he found that the zip cord that everyone used at the time, added enough inductance and there was NO problem with oscillation. Remember, the time was the early 1970's. LATER, when exotic cables were offered, MANY amps tended to oscillate, coil or not, and had to be redesigned. Naim had to do SOMETHING to keep their customers from using exotic and hi cap wire, so they provided one for their customers to use, instead of zip cord, which was considered 'obsolete' at the time. This way, they controlled the inductance, and the amps remained stable, without adding a coil which makes a bigger negative difference to the sound than many here yet realize, especially with 2uH or more, which would be necessary to do anything useful in Naim's case. Remember, this was the 1970's. I suspect that in later years Naim ran on its own inertia, and Julian concentrated on other projects. He might be criticized for this, but it is 'water over the bridge', now.
It was a case of the snake oil merchant peddling more snake oil to the masses under the guise of further improvements, which we now know was to compensate for an inadequate design

Hell a lot of people were probably running those amps close to instability with a few or more volts of HF instability heating up their voice coils in their tweeters without them even knowing it No there is a solution !!! Buy our exotic cables which will improve the sound even further (you mean stop that oscillation) !!!

What a scam !!!

Apart from some HF roll off, John can you please explain those detrimental effects to the sound of a relatively low valued air cored inductor in series with a loudspeaker load ??

Lets face it nearly every multi way loudspeaker uses a passive crossover with at some series inductance and every direct radiating moving coil loudspeaker has some parasitic non linear series inductor due to its voice coil and magnet structure

John , should be we worried about those detrimental effects on sound and what can we do about it now ??
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Old 6th July 2008, 04:16 AM   #35
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Snoopy, you are libeling Julian Vereker. I take exception to you and your lies and accusations.
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Old 6th July 2008, 04:22 AM   #36
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Originally posted by bear
snoopy,

My recollection - a non-technical one at that - was that Naim marketed well in Europe and then parleyed that into a US/North American presence, using the "Euro" angle for that. It appealed to those who did not want/like the typical American "big techno gear" look (Crown, Phase Linear, SAE, others...), and prefered that understated smooth look but didn't have the bux$ for B&O!

bear, the Japs were kicking goals in the early 70's if my mind serves me correctly.

Yamaha and Sony were pushing the technology envelope with VFET devices. The Yamaha B-1 and B-2 VFET amplifiers are still an amp that is well sort after on the second hand market. Accuphase and Luxman had there own offerings as well as many others.

http://www.thevintageknob.org/VFET/B2/B2.html

http://www.thevintageknob.org/VFET/TA8650/TA8650.html

I owned a Luxman SQ507X in the early days. I believe it was of 1975 Vintage. Not the biggest offering from Luxman (50 watts per channel) but a lot cheaper than a Naim of the same power rating and a lot more reliable It was a fully complimentary design and it never blew up and lasted for years

Now lets have a look at the output devices. A single pair of 2SD218 and 2SA649.

2SD218 = 150V / 7A / 60W / fT = 10 Mhz
2SA649 = 150V / 7A / 60W / fT = 10 MHz

Big Fizz about Naim using High fT power devices They weren't the first to use them and again the Japs were well ahead of the pack with their designs using complimentary devices )

It was not until the 80's that Sanken started to fabricate high powered high fT devices for use in mass produced Japanese product. As well the Japanese also offered a lot of innovative design solutions to match these new devices. It's ironical that the Japanese products at the time left the offerings of the likes of Naim for dead but still there were people willing to fork out big dollars for the same old snake oil

What is even more ironical today is that those Jap amps that many people turned their noses up in the early days are now a hotly sort after item on the second hand market and the likes of Naim have more or less been relegated to the trash can
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Old 6th July 2008, 04:35 AM   #37
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Originally posted by john curl
Snoopy, you are libeling Julian Vereker. I take exception to you and your lies and accusations.
The only thing that the dead owes to the living is the truth !!!

I'm just having the last say to those people who owned Naim equipment and just because they paid a lot of money for it, used to stick their nose up at Japanese equipment which at the time was technologically much more superior in every way and excellent value for money

John, if you are an objective person then you should agree with me instead of taking sides just because he is your mate
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Old 6th July 2008, 04:36 AM   #38
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Snoopy, are you just a young kid? Have you no sense of history, or understanding of marketing, or how prices change between countries? Almost all Japanese audio equipment came to the USA DISCOUNTED by the manufacturer, under some sort of trade agreement. IF I tried to buy a Denon cartridge in 1978, for example, it cost me MORE to buy it in Tokyo, than in San Franscisco. WHY?
Yes, Naim was overpriced and overmarketed, but it was successful in getting worldwide acceptance. It was reasonably priced in the UK for its performance quality. Could you do something like that? I could not. Perhaps, I marketed too little and charged too low a price, I don't know for sure.
When it came to parts, it is true that the Japanese started to make better parts, BUT I used Motorola, just like Marantz, GAS, SAE, JBL, and just about everybody else. HK used quasi comp in their Citation power amp in 1977 when I worked there. The lower voltage Motorola devices had an F(t) of 2-4MHz. Higher voltage Motorola devices had an F(t) of 2MHz from the same die and just a different diffusion, and with a much higher beta non-linearity.
We didn't have access to Japanese devices, but I would agree that they ultimately made better devices for audio than the Americans made after 1978, or 30 years ago, and I use almost all Japanese parts, and have done so for decades. So what is your problem?
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Old 6th July 2008, 04:50 AM   #39
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Quote:
Originally posted by john curl
Snoopy, are you just a young kid? Have you no sense of history, or understanding of marketing, or how prices change between countries? Almost all Japanese audio equipment came to the USA DISCOUNTED by the manufacturer, under some sort of trade agreement. IF I tried to buy a Denon cartridge in 1978, for example, it cost me MORE to buy it in Tokyo, than in San Franscisco. WHY?
Yes, Naim was overpriced and overmarketed, but it was successful in getting worldwide acceptance. It was reasonably priced in the UK for its performance quality. Could you do something like that? I could not. Perhaps, I marketed too little and charged too low a price, I don't know for sure.
When it came to parts, it is true that the Japanese started to make better parts, BUT I used Motorola, just like Marantz, GAS, SAE, JBL, and just about everybody else. HK used quasi comp in their Citation power amp in 1977 when I worked there. The lower voltage Motorola devices had an F(t) of 2-4MHz. Higher voltage Motorola devices had an F(t) of 2MHz from the same die and just a different diffusion, and with a much higher beta non-linearity.
We didn't have access to Japanese devices, but I would agree that they ultimately made better devices for audio than the Americans made after 1978, or 30 years ago, and I use almost all Japanese parts, and have done so for decades. So what is your problem?
John, the Jap stuff came to Australia and was still a lot cheaper than the Naim equipment of the day. Although Australia didn't benefit from the quantity discount that the US did, none the less the Jap stuff was still exceptional value for money. And I agree the design of the HK Citation Quasi Comp amplifier would have been a lot more refined than the Naim offerings

In terms of technology the amps that Naim offered were no better than the kit amps from the local Electronics magazine and they could be bought and built for a song. Now come to think of it the ETI5000 100W per channel Mosfet amp from ETI magazine in the early 80's was a step up again and IMHO was superior to the Naim equipment Like I said Naim had a very good marketing campaign and technically ignorant people translated big dollar price tags along with the Pommy badge into superior quality and performance. But that wasn't the case for that brand
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Old 6th July 2008, 05:16 AM   #40
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I was being polite, but you need more clarity. I would assert that Japan DUMPED audio equipment into the USA and Australia. Only because Australia has high import duties, and the USA had low ones, that it made any difference.
IF you import something from the USA to Japan, even at normal or lower than wholesale prices, it will retail at about 3 times what it would cost in the USA. IF you bought audio equipment in Japan in 1978, that was Japanese made, it cost more than what it would cost in California. This 'dumping' caused many American companies to go out of business. Now, everything is done in China, and the same thing is happening.
Naim equipment, either in the USA or Australia was no bargain, and you probably could do better. However, in the UK, it was better than most British products, and remember that American products sent to the UK would cost twice what they would cost in the USA. This made them overpriced for the British market, but OK for the American market.
This is just about marketing price, but where the Japanese and many others have failed is in making a piece of audio equipment that really sounds good. This is because of engineers not believing their ears, and only reading their meters. This is what separates good sound quality from bad sound quality, not engineering tricks.
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