Official M2 schematic

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WalterW

Member
Joined 2012
Paid Member
generg said:
You remember Nelson hints for the output pair matching….?

if not look here

http://www.diyaudio.com/forums/pass-labs/281520-official-m2-schematic-6.html#post4495215

Because I was a bit irritated he was so friendly to give me an "extended version"…… THX Nelson!

"The numbers are get have about 1 volt more Vgs (about 5V) for P channel FQA12P20
vs about 4V for FQA19n20c at 1 amp (cold). That is why you see the trim pot on the
top side for the DC offset.

"The transconductance of the N type is a little higher, but in practice I see a consistent
3rd harmonic character, so it’s not much higher.

There are better parts out there, although my favorites would be the Toshiba 2SK1530
and 2SJ201. If you look them up you will see why, but they are discontinued."

hope sharing Nelsons words is no sacrilege in this case….. :)
Click to expand...

Thanks!
 
generg

generg

Member
Joined 2009
Paid Member
Oh…….. tagalog?

when I put them in my F5 there was only one point their drift was higher with temperature.

somewhere I read that they have a different pin orientation, I just checked the pdfs, but I saw the normal Gate-drain-source configuration we are used to….

But please check yourself here for the 2SK1530…...
 

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ElFishi

ElFishi

Member
Joined 2008
generg said:
for German colleagues possibly interesting…more leftovers

https://www.csi-elektronik.de/2SJ201-J-Transistor

2SK1530
Click to expand...

Generg,

thanks for those hints. You list two suppliers, csi-elektronik for 2SJ201 and kessler-electronic for 2SK1530. I (and jp) checked both websites and found that kessler only carry 2SK1530, but csi actually carry both 2SJ201 and 2SK1530. They call it "2SK1530-Y-TOS", is that what I am looking for?
If so I could source both from kessler, right?

Looking for the Fairchilds I found that the seller "jims-audio" offers pairs on ebay. Apparently this seller has a good reputation, is there anyone who can back this up?

Edit: apologies Generg, I overlooked you response to JP
 
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ElFishi

ElFishi

Member
Joined 2008
Q to CSI: "könnten Sie mir bitte mitteilen, ob die Bauteile 2SJ201 J-Transistor ArtikelNr.: 23321 und 2SK1530-Y TOS Transistor ArtikelNr.: 48542 Originale von Toshiba sind?" (Are the parts Toshiba?)
A from CSI: "nein, es handelt sich hierbei um Fernostware" (No, they are far east goods)
 
buzzforb

buzzforb

Member
Joined 2010
The output stage is a buffer. The Fairchild are better compliments than the IRF and result in lower distortion and slightly different harmonic profile. The Toshiba are an even better example of complimentary devices and will probably just extend the performance improvement further. They both are most likely just showing or revealing the nature of what is driving them, in this case, the transformer.
 
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