Important transistors?

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jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

to my ears it does iv owned a tb for 15 years most clones including x0x have some strange bubbly thing going on witch i dont really like , maby its my imagenation or something but its all those subtile changes that cant be describet actualy makes every maschine difrent, atleast thats my oppinion if im allowed to have on :)

even if its like you say witch it prolly is , its not the same as twisting the knobbs

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antto
 
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Re: Important transistors?

Post by antto »

what are you talking about?
"bubbly thing going on" is that when you change Q8 or Q9/Q10?

i don't like to believe in voodoo, i like to know what is going on instead
so if you don't mind, let's find out what the "bubbly" thing is exactly
find some other transistor (even if it isn't 733) with the same hfe value as the one which you say sounds "good" and let's see if it sounds the same

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

i dont care if its voodo or not :) eehhh to me it sounds abit more watery like flah flah insted of fah fah with the low beta transistors in , perhaps i could change everything to get it more audioble?! i know its realy hard to hear but once you do you always hear it , its like when you find a dead pixel on the screen you know,

i dont have more transistors with 400hfe

iv got 7 x0xkit transistors , 230-260 hfe

ill se what i can do

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antto
 
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Re: Important transistors?

Post by antto »

is that in Q8 or Q9/10?

iirc higher hfe in Q9 would push the overall cutoff frequency of the filter up, nothing more

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

to be hones it sounds like its supressing the cutoff with high beta , now im confused :) its sound like totaly diffrent settings on the knobs but i did not touch a thing

q8/9 and 10

http://www.subatomicglue.com/x0xl0g/733k-analysis/

if you havent already something differs hard to describe , if it only affect the cutoff im not so sure it has to be something else there but what you said just and what i heard from low -> high beta it seems to be the opposit ill post a wave on that

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

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antto
 
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Re: Important transistors?

Post by antto »

leave Q8 alone, no need to put transistors with different hfe there as the hfe makes no audiable difference

i don't want to open my x0x right now to verify, but iirc either Q10 or Q9 didn't make much difference

that article, it's a common misconception that the resonance is higher when actually only the cutoff frequency is
the 303 filter has more resonance on higher cutoff frequency, so when you bump the cutoff up - it looks like there is more resonance (and there is) but don't blame the transistor for that

have you ever tried what TM3 does?

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

dont have the schematics infont of me tm3??!! power? no i havent i just compleated the build 2 days or so ago ,

id still say q8 makes difference not much perhaps i most cases not audioble but if you overdo it :)

i found a 74hfe transistor motorola bf762 from an old reciever i belive , i admit its not much diference in q8 but q10 daaam it was cheesey as hell not god at all :),

now i whised i did socket everything i wanna try more :)


oooh found a 1279hfe do i dare put it in :)? hehe

1200 on q10 nothing happend not even a sound

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antto
 
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Re: Important transistors?

Post by antto »

yes, that's what i meant
Q8 - hfe makes no audiable difference
Q10 - hfe no difference at all
Q9 - hfe is responsible for the amplification of the cutoff frequency for the filter

TM3 - that's in the VCF, adjusts the filter cutoff frequency (it's there to compensate for the variable hfe on Q9)

jimmy303
 
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Re: Important transistors?

Post by jimmy303 »

i just wrote hfe had a huge impact on q10 ;) the lower the worse to high around 1200 it couldnt produce sound at all (if you overdo it)
q8 its at least measureble with the scope
q9 yes it is thoug it feeds 10 and 11 but you already knew that (and yes it sounded like twisting the env or cutoff a fraction)

tm3 oops i spend about a ouhr to tweek it or played with it i should have known :) sry
i think tm3 will do better on a pot in the case rather than on the board

but i think you are right i a way those poor 3 transistors dont do much alone besides pushing the filters, its alot more to it then just tree transistors that i totaly agree with.
there are so many other componets that has something to say about it so its prolly not worth hunting for high gain on those three

i would like to hear a box with overall low hfe NPN/PNP some people like that and build accordingly ill stick to my original transistors feels good :)

i must say i am surprised about the sound in x0x its really good and alot of it has to do how you stroke your baby its the same with the tb if one doesent grasp how to twiddle both sound like cr#p (ofc thats induvidial).

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