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-   -   MPSA 18 vs. BC546B's (http://www.diyaudio.com/forums/pass-labs/6498-mpsa-18-vs-bc546bs.html)

cowanrg 1st October 2002 10:11 PM

MPSA 18 vs. BC546B's
 
hey, i finally got all my boards and am ordering supplies and have a couple questions regarding the MPSA18 transistor...

i was told that the BC546B is a bit better than the MPSA18. so, the questions, which is better, where is the best place to get them, and do i need to do matching?

pretty straight forward, thanks.

mefinnis 1st October 2002 10:26 PM

At one point in time I asked Nelson, "I note you change from the MPSA18s to ZTX450s between the A5 and A4. The later are much easier for me to locate and I wondered if they were exchangeable"

To which he replied, "The bipolars in this circuit are completely generic, and the ZTX450's were chosen for price and availability. np"

That is, any equivalent will do.

cheers, mark

cowanrg 1st October 2002 10:39 PM

ok, that answered my first question.

do i need to match them? i have already found a few places to get them from, but i just need to know if matching is necessary or not.

mefinnis 1st October 2002 10:55 PM

No. But they are "as cheap as", and obsession is a quality I admire ;)

cowanrg 1st October 2002 10:57 PM

ok, now im confused...

if time is not an issue, and since the price is negligable, would it be worth it to just go ahead and match them? keep in mind im building 8 channels of aleph2....

jh6you 2nd October 2002 09:19 AM

I am silly. My friends call me so.

Whatever I make, I use only the matched components.

Matched transistors...
Matched JFETs...
Matched MOSFETs...
Matched caps...
Matched coils...
Matched resistors...
Matched cable length...
Matched chassis...
Matched transformers...
Matched knobs...
Matched bridge diodes...

Sound silly, but this is the right solution.

Please believe in me. Just go ahead.

cowanrg 2nd October 2002 04:17 PM

yeah, actually, i over-ordered everything...

im gettting like 3600+ resistors alone just so it is all matched.

the black gates (220uf) will be the only non-matched component. even the small caps on the board will be matched. eh, since the transistors are so darn cheap, ill just match them as well i guess.

skaara 2nd October 2002 05:18 PM

A little offtopic, but, will mpsa42s be ok too for aleph 2?

PedroPO 2nd October 2002 07:09 PM

:D

jh6you
Quote:

Matched transistors...
Matched JFETs...
Matched MOSFETs...
Matched caps...
Matched coils...
Matched resistors...
Matched cable length...
Matched chassis...
Matched transformers...
Matched knobs...
Matched bridge diodes...
Did you also had your HEARS matched?



where did you matched them? ;)

wuffwaff 2nd October 2002 08:28 PM

cowanrg,

why would you use a BC546 B? You can also use a BC550 C with higher Hfe and lower noise. I used them in my Aleph5 and will use them in the next Aleph Im building.

william


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