advertisement


SM8927 transistors (NAP250 CB BU)

The SM8927 is the manufacturer and date code - SM - semelab, 1989, 27th week - this have been serviced before perhaps...mine has BDY58s dating from 1977. But I'm going to rebuild with MJ15003s
 
nonsub said:
Neil you busy dude, I been trying to call you!

Tell me whats good with MJ15003s ?
Click to expand...

Yes, I've been out a lot lately, but I'm in all day today and tomorrow...

...from acoustica.org.uk...

These are TR11 & TR12 in fig1. Naim use custom NA001 transistors sourced from Semelab. However they are not deeply magical parts and alternatives are quite acceptable. Alternatives in TO3 cans that have been used as replacements are BUV20 at about £12 each and MJ15003 at £3. Both recommended by Les W. He states, and I paraphrase, that he considers the MJ15003 very very agile and informative but the BUV20s deliver the power and the glory.​
 
When I built my NCC200 boards last year Les recommended the MJ15003 to me in preference to the BUV20
 
misterc6 said:
When I built my NCC200 boards last year Les recommended the MJ15003 to me in preference to the BUV20
Click to expand...

neiljadman said:
.... He states, and I paraphrase, that he considers the MJ15003 very very agile and informative but the BUV20s deliver the power and the glory.
Click to expand...


ugggh nothing is a simple decision, i think maybe I'll wait to hear Neil's results lol
 
I've read sometime ago that BUX20s were used in the bid Naims amps. Can they be used is NCC200 or NAP250 without mods ?
 
Ramona do you know where you read this? Also what do you mean by "used in the bid Naims amps" ... BIG maybe? Thanks.

The specs for BUX20 look very similar and they seem to be more available than BUV20 at this time.
 
Unfortunately I have not had time to complete my NCC200 build due to work, life etc etc etc. I have tested the module for correct functioning and bias setting etc and all seems well. I have used the BUV20’s which I had bought some years ago and I am going to build a second set of NCC200 modules using the MJ15003’s. That way I can make a direct comparison between the two types of output transistor. I will report back with my finding as soon as completed.

With regard to whether you should use the MJ15003’s, BUV20’s or BUX20’s I cannot help with that. What I will say is that the price difference between these transistors is huge or at least between the MJ15003 and the rest there is a big price difference.
Availability of all these transistors from www.farnell.com are no problem, but be aware of BUV20 fakes on Ebay.

One other thing is that if you look closely at the photo of the NCC200 modules on the Avondale Audio’s web site there are BUV61’s fitted to the module. http://avondaleaudio.com/high-end-audio/power-amplifiers-module/ . Is the BUV61 another suitable alternative? although very expensive.
 
neiljadman said:
The SM8927 is the manufacturer and date code - SM - semelab, 1989, 27th week - this have been serviced before perhaps...mine has BDY58s dating from 1977. But I'm going to rebuild with MJ15003s
Click to expand...

Why rebuild at all? Are the MJ15003s supposed to be superior to the BDY58s? Or is it likely the latter have degraded over time? All self-interested questions as my 250 has BDY58s dating from 1979.
 
DubbLinn said:
http://i510.photobucket.com/albums/s343/DubbLinn/Hi-Fi DIY/NAP250AmpBoards.jpg
My NAP250's T03's are 001 SM3282 and are working perfectly after all these years of use and abuse. I did replace the elect. caps etc which were passed their sell by date and now plays as good as new. Those 10uF caps looked perfect but when removed from the board one tested as dead (<1uF) and the rest also tested out of spec.
Click to expand...

Your photo is of the regulator boards, not the amplifier boards :confused:
 
On another forum I saw this:

001 transistors in TO3 package (a special BUV20 made by Semelab)

Does this mean current incarnation of BUV20 isn't the same?
 
You must log in or register to reply here.


advertisement


Back
Top