Important transistors?

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Pish
 
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Important transistors?

Post by Pish »

Is there an order of highest beta to lowest for 733P and 536F?
As in people say that Q11 has a big effect.

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decoder23
 
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Re: Important transistors?

Post by decoder23 »

i have built about 20 x0xb0xes so far and i get the best sound (my subjectiv opinion) with all 2sc536f with low HFe ratings < 240 and 2sa733ap with HFe ratings around 300.. for q11 you could try the 2sc945p types instead of the 536f. q9 didn't have such a big impact to the sound, when testing different HFe ratings, q8, 10 and 11 do.

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antto
 
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Re: Important transistors?

Post by antto »

q8 hfe affects sound? got audio recording of it?

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

antto wrote:q8 hfe affects sound? got audio recording of it?
No audio but there is defenetly something going on when changing from low 240 to high 400 beta, that is changing from kit 2sa733 to original tb303 transistor the shape is NOT the same therefore the audio will not sound the same ,
thoug im not the one who says it does :)

hmm btw q8 is the squere right?, you know how it looks and with original tb transistor the base gets elevated i tiny fraction,
dunno if my scope is broken dont think so thats the best way i can describe it.

and i dont really think annyone could ever tell the difference but its there, perhaps someone else can confirm

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antto
 
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Re: Important transistors?

Post by antto »

IMO the audiable characteristic of the square is the pulse width
Q8's hfe doesn't affect it, it only affects the "knee" transition in a subtle way

i have tested about 20 different transistors (all kinds with all kinds of hfe) which all worked without any audiable difference
i have the modern 733 but not the old one, so i haven't tested the old one, but i would expect the same results, unless there is something special about it's properties

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

yhea its prolly not audioble, i do have 5 of the original tb tranistors in it now, iv had a thougt about laborate a bit.
most of the transistor are socked so if youd like me to test some original let me know to compare with low beta lowest iv got is around 230.

I´d like to compare it side by side with a stock x0x much easier to spot variations then ,

oh just found a picture of what i mean look closely on the tb303 schematics on the square see the bottom ?! its not straight it was with low beta with high it is like the picture.

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antto
 
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Re: Important transistors?

Post by antto »

sure, audio recordings are always welcome ;]

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

Ok a fast test i switched something its upp to you to figure out :) NO knob has been tuched in annyway during this test

can you hear the difference? or am i mesing with you ;)?

what did i do?
witch one sounds best IF anny difference?!

:)

https://soundcloud.com/jimmy303/this-is-a-secret-2

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antto
 
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Re: Important transistors?

Post by antto »

the only difference i can hear is, in the second half - the envmod is reduced
the actual square wave has no audiable difference anywhere

what are you doing?

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

not turning the knobs thats for sure ,

i swaped betwen tb and x0x stock transistors

witch one you think is original x0x and original tb?

it does something to the whole sound its quite diffrent i my ears

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antto
 
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Re: Important transistors?

Post by antto »

wtf
are you sure you're swapping at Q8?

also, it's not great that the recording is processed with effects

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

some slight delay doesent hurt , no its not q8 , its q9/10 higher beta seems to remove the vobbely styff witch i dont like , whant me to try anotherone?! takes me 1 sek have it all infornt of me

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

https://soundcloud.com/jimmy303/q8-low-vs-high-beta

high vs low hfe aka beta on Q8 its definitely a difference going on here its subtil but its there did i prove you wrong now :)?

dont stare yourselfe blind on the square im 100% sure you will here it

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antto
 
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Re: Important transistors?

Post by antto »

okay, so you changed the Q9/Q10
that's completely different and affects the filter cutoff coupling (aka cutoff frequency)
it won't remove any sort of bubbling tho, it simply scales or shifts the cutoff frequency for the filter (which can be compensated with TM3)

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antto
 
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Re: Important transistors?

Post by antto »

okay, heard the Q8 recording now, no audiable difference in the square, as expected

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