Q28 and Q39 - 2SK30A

by rarara on Wed Feb 13, 2013 5:54 am

OK, while I wait for my 733's and 945's to arrive by post :roll: i was reading a bit more about what should be in various other places. Currently I have this:

Q28 - 2sk30a-o
Q39 - 2sk30a-y

Is that the best combination for these places? originally I was finding suggestions to avoid Y's, but then saw mention of Q28=o and Q39=y as being optimum.
Last edited by rarara on Wed Feb 13, 2013 11:06 am, edited 1 time in total.
rarara
 
Posts: 168
Joined: Wed Apr 05, 2006 8:47 am

Re: Q28 and Q39 - 2SK30A

by antto on Wed Feb 13, 2013 8:40 am

Q39 is in the ENV section, don't expect it to change the sound much
Q28 is for the sawtooth, i bought about 5 J201s and it didn't made any difference in that spot
but if you somehow manage to change the sawtooth - that would have an effect on the square wave too (cuz it's a waveshaper after all)
We are here too: irc.freenode.net >>> #x0xb0x
..:: c0nb0x v1.00 ::.. http://forums.adafruit.com/viewtopic.php?f=7&t=29282 (new control app - win/osx)
VCO Tuning: http://forums.adafruit.com/viewtopic.php?f=12&t=24759 (do it the EASY way)
User avatar
antto
 
Posts: 1348
Joined: Thu Apr 15, 2010 2:21 pm
Location: 127.0.0.1

Re: Q28 and Q39 - 2SK30A

by rarara on Wed Feb 13, 2013 11:17 am

Am not surprised as there is a lot of talk of J201 being a good substitute for the K30A in Q28. I suppose what i was trying to resolve was the use of 2sk30a-y anywhere, since 2sk30a-y and 2sk30a-gr were descibed by a lot of people as the types to avoid (but that was maybe just in Q28 and didn't apply to Q39?)
rarara
 
Posts: 168
Joined: Wed Apr 05, 2006 8:47 am

Re: Q28 and Q39 - 2SK30A

by antto on Wed Feb 13, 2013 3:12 pm

i gotta have at least 2 parts which make some measurable difference
otherwise i cannot say anything

but Q39 is part of the envelopes..
iirc, the main envelope (for the VCF) is generated by C62 which gets charged up and discharges down exponentially, with time constant which can be affected by the Decay knob or not (depending on the accent CV)
then there's Q40, Q41 and Q39
no idea what their purpose is exactly, but one of them surely is used as a buffer i guess
from there it goes to IC12A which is part of the accent-sweep circuit
i don't expect any magic to happen depending on Q39

still.. if you (or anyone who's reading) have the parts - you can always socket Q39 and Q28 and test
We are here too: irc.freenode.net >>> #x0xb0x
..:: c0nb0x v1.00 ::.. http://forums.adafruit.com/viewtopic.php?f=7&t=29282 (new control app - win/osx)
VCO Tuning: http://forums.adafruit.com/viewtopic.php?f=12&t=24759 (do it the EASY way)
User avatar
antto
 
Posts: 1348
Joined: Thu Apr 15, 2010 2:21 pm
Location: 127.0.0.1