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Old 21st November 2005, 04:46 AM   #21
jam is offline jam  United States
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Quote:
how come you are so keen to BJT output tranies, should it not be lateral FET's to make you post, or are we seeing Ayre with BJT's in the output soon?
................................only the Shadow knows!

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Old 21st November 2005, 10:17 AM   #22
lohk is offline lohk  Europe
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NAP250 uses -001 transistors in TO3 package (a special BUV20 made by Semelab)

NAP500 uses -007 transistors in TO3 package (also made by Semelab)

NAP150 uses SANKEN 2N2922 like the discontinued NAP140


quote Julian Vereker (in HIFI+ #4/99) about the development of the NAP250:

"... I wanted a transistor which was very fast (rather than necessarily linear), without any storage time especially at low currents, and I wanted it to turn off at low currents. ..."
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Old 21st November 2005, 10:18 AM   #23
lohk is offline lohk  Europe
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the -007 transistor very likely is the Semelab BUX20
http://www.semelab.co.uk/pdf/bipolar/BUX20.pdf
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Old 21st November 2005, 01:11 PM   #24
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Quote:
Originally posted by jam
................................only the Shadow knows!
Only the Shadow and about 1,000,000 other people. For example, see:

http://www.soundstage.com/revequip/ayre_v5x.htm

where it is revealed "So when Hansen designed the V-5, he used FETs in the input stage and bipolar output transistors at the output -- 16 of 'em in each channel."
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Old 21st November 2005, 01:43 PM   #25
jam is offline jam  United States
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......................oops!
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Old 21st November 2005, 01:51 PM   #26
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Quote:
Originally posted by lohk
NAP250 uses -001 transistors in TO3 package (a special BUV20 made by Semelab)

NAP500 uses -007 transistors in TO3 package (also made by Semelab)

NAP150 uses SANKEN 2N2922 like the discontinued NAP140
Thanks for the info. Semelab is a small UK-based foundry that is willing to do specials and custom parts. (They are the ones who make the Exicon and Magnatec lateral MOSFETs.)

According to the Naim website:

http://www.naim-audio.com/products/nap250.html

"The NAP 250 uses the same 007 transistors that were custom-designed for the NAP 500. 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)."
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Old 21st November 2005, 02:13 PM   #27
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That's a different NAP250 to the one pictured up-thread, FWIW. Only the name(!) remained the same.

I have a mid-70s NAP250, which is a similar design to the one pictured up-thread but a different case style and circuit arrangement and that's fitted with 8 BDY58s. FWIW.

Paul
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Old 21st November 2005, 02:27 PM   #28
lohk is offline lohk  Europe
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Naim changed the output transistors for the 250 in the late 70ies (aprox.) from BDY58s to the mentioned 001 propriate designs. Since then the classical 250 used this transistor. The new 250 is another story, using different regulators and amp inputs AFAIK.
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Old 21st November 2005, 02:36 PM   #29
lohk is offline lohk  Europe
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I have very good experiences using the Cyrus PT7 (TO-220, BUV28?) and PT77(TO-247, another switching transistor?) in Naim clones. The smaller amps can use the BD911 or like other smaller Naim amps the BD743 (the NAIM NA-005). The older version of the NAP110 used the BUV20.
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Old 21st November 2005, 03:44 PM   #30
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Quote:
Originally posted by Charles Hansen
bipolar output transistors at the output -- 16 of 'em in each channel."
Some may wonder what those 16 high-current bipolars might be, 007s as well ?
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