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Charles Hansen 19th November 2005 11:19 PM

New Naim Output Transistors
The new series of Naim amplifiers has an unusual output device. From their website:

"A bipolar transistor with a specification combination of very high current, power rating and bandwidth was needed, far in excess of anything available to Naim before. A suitable output device was eventually developed after six years' collaboration with a semiconductor manufacturer.

"These outstanding components each provide up to 80 Amps and 350 Watts, negating the need to use parallel pairs of transistors (which always have a negative effect on sound). Additional 007 transistors are used in the fully regulated power supply, ensuring the very best performance."

My understanding is that Naim uses quasi-comp output stages, so I would assume that these are NPN only. This is still an extremely robust part. Does anyone out there have any more information on these parts?

calvert73 19th November 2005 11:46 PM

Naims own custom design
Not available I'm afraid, custom designed and manufactured for Naim exclusively, love to try them though!


sss 19th November 2005 11:56 PM

Re: New Naim Output Transistors

Originally posted by Charles Hansen
" negating the need to use parallel pairs of transistors (which always have a negative effect on sound).."

yeah right :rolleyes:

Charles Hansen 20th November 2005 01:26 AM

Does anybody know what package they are in? It would have to be pretty darned big to safely dissipate 350 watts.

Any guesses on the manufacturer?

jam 20th November 2005 02:13 AM

I don't if this would be of any help .............

Transistors NA001 MJ15003 output transistors, BUV20 also good but expensive Farnell 3
Nait One Trannies
Try: BD711 - NPN & BD712 - PNP, both 12A @ 100V, 75W TO220 NPNs are numbered 003, PNPs numbered 004

ZTX384s may be replaced by BC182 or BC546. Also ZTX651Q & 751Q
NA005 BD743's will replace the NA005s- recommended by Naim.
ztx 653 npn used to replace ztx 652 N/A N/A N/A


jam 20th November 2005 03:34 AM


From some review I learnt that the transistor has a house marking of NA001. A review is in issue #8 of Hi Fi+ (NAP500) might shed some light on the subject, sorry I do not have that issue.

From my post above, taken from some web site, it seems that the NA001 is a MJ15003 which makes it a Motorola TO-3 device..............but then again I could be wrong.



PS The NAP500 is a bridged amp rated at 140W, may be the lower rail voltages....................., there is also the Motorola BUV20 which is more likely (higher ft )

............or it might be some OEM Sanken device.

Charles Hansen 20th November 2005 03:55 AM

Hi Jam,

Thanks for the detective work. The Naim website calls this part the "007", so I think it is different than the "001" Motorola part. I think I have issue #8 of Hi-Fi+ at work. I will look for it on Monday.


anatech 20th November 2005 04:08 PM

With that power, they may just be using a new industrial package part. Since they like NPN devices, they don't need a compliment.


sss 20th November 2005 04:26 PM

some to-3 trannsistors can dissipate 350W

Upupa Epops 20th November 2005 07:31 PM

Why do you mean, that paralleling have negative impact in sound, Charles ? Have you some proofs for this statement ?

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