2SK30A-O locations?

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brandon daniel
 
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2SK30A-O locations?

Post by brandon daniel »

If I were to get a hold of some 2SK30A-Os, where would be some good places to replace the Ys currently in the x0xb0x?

Q28 in the 303 used one, but this is the only place obviously marked as such in the 303 schem I have, was this the only location it was used over the Ys? Is it a drop-in replacement in the x0x or have other parts been compensated for differences?

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Post by Guest »

q28 was the only o type
it is a drop in replacement

moogah
 
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Post by moogah »

In case people were wondering, dalbani.co.uk has these along with the other two sk30 variants. Now if we could get some data on sonic differences...

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altitude
 
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Post by altitude »

I found none. Sounded the say with the y or o

Fiercefish
 

Post by Fiercefish »

No discernable difference here either, I tried 10 different O's and none sounded any different to the Y. Strange though because the 303 service docs specify the q28 is an O.

I think Q8 is the crucial component in nailing the 303 square wave, I have just got 50 733's and am going to try them all!
I use a socket and just swap them out.

adafruit
 
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Post by adafruit »

I'd guess its because the O type is cheaper than the Y type. The O type is used as a buffer so that gain isn't that important. the Y type is used as a JFET current source where the gain is essential.

Fiercefish
 

Post by Fiercefish »

Interesting, some techs maintain that q28 is responsible for the 303's skewed square wave but clearly it is not. So what else could be causing the difference? I also used a high beta (325) 733 in q8 but this did not make much difference.

Seems that the 303 is a bit of a mystery, funny that some snobs shun it for being so simple!

So Limor, what else could I try?

PS I am experimenting with some cool mods which I will post when finalised.
Any luck with the battery mod yet? <bump> :wink:

FF

adafruit
 
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Post by adafruit »

Fiercefish wrote:Interesting, some techs maintain that q28 is responsible for the 303's skewed square wave but clearly it is not. So what else could be causing the difference? I also used a high beta (325) 733 in q8 but this did not make much difference.
while some people claim q28 has an effect on the square wave, we havent seen any strong justification as to why it should (other than "its in the signal path") like scope traces or at least a doubleblind test. Its likely that the last minor differences are due to using 733p vs. 733ap and the stiffer power supply. And of course, personal opinion: you could probably take two 303's, call one a 'clone', and demo them to people and they'd complain that one of them "isn't quite right"...
Seems that the 303 is a bit of a mystery, funny that some snobs shun it for being so simple!
You could clone the 303 as precisely as you'd like, just takes more time to analyze. The design itself is pretty simple, its just the way it fails that is complex.

Fiercefish
 

Post by Fiercefish »

And of course, personal opinion: you could probably take two 303's, call one a 'clone', and demo them to people and they'd complain that one of them "isn't quite right"...
Agreed!

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