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 Forum index » DIY Hardware and Software » YuSynth
resonance issue with Steiner VCF
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space_zulu



Joined: Dec 15, 2014
Posts: 14
Location: france

PostPosted: Wed Jan 07, 2015 12:38 pm    Post subject: resonance issue with Steiner VCF Reply with quote  Mark this post and the followings unread

Hi everyone, et salut yves Wink

this is my first topic on EM, and i'm having little issue with the yusynth steiner filter :

i have a nice and smooth filtering with each filter (LP, HP, BP, AP), and resonnance seems to work fine i hear the effect it does (and compared it with my microbrute and its pretty close and i'm very glad of it ! Smile

but ! the resonance isn't strong enough and i don't have any self-oscillation point, i looked at the schematic but i didn't really get exactly where is the whole resonance circuit and how it works (i just understood that it use IC1b and c in the revised version (http://yusynth.net/Modular/Commun/STEINERVCF/Steiner-improved-sch.gif) )

i run the module on a self made +/-12v PSU and i etched the PCB at home
if anyone had a clew on where to look and/or what to do it would be really helpfull ! Smile

thanks a lot

Zulu.
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elmegil



Joined: Mar 20, 2012
Posts: 1582
Location: Chicago
Audio files: 14

PostPosted: Wed Jan 07, 2015 4:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

The resonance is the path through ic1b and ic1c and the resonance pot. If you have a problem causing this, it would be along that part of the schematic.

However, my first suspicion is that using 12V, there is some adjustment needed because this is originally a 15V circuit. I don't have any expertise in this circuit in particular, but I bet some searching around the YuSynth forum here might find something about that.
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space_zulu



Joined: Dec 15, 2014
Posts: 14
Location: france

PostPosted: Wed Jan 07, 2015 8:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi and thanks for the reply,

at least i was right for the part of the schematic in cause, that's nice ! Smile

but i'm a bit surprised because Yves said that it is possible to run it on 12v without mods that why i posted here,

i'll try to change the gain of the IC1c amp and let you know
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AlanP



Joined: Mar 11, 2014
Posts: 51
Location: New Zealand

PostPosted: Wed Jan 07, 2015 9:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

On the schematic, R18 is listed as 3k9 -- with the note at the bottom to change it to adjust the resonance range. Mine runs on 12V (Euro).

Think I might try swapping it out for a 5k or 10k trimmer on my two, just to see what happens. Probably need to -- it's hard on mine to get any self-oscillation that isn't high pitched.
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space_zulu



Joined: Dec 15, 2014
Posts: 14
Location: france

PostPosted: Thu Jan 08, 2015 2:44 am    Post subject: Reply with quote  Mark this post and the followings unread

that's what i was going to try but i don't understand if it mean the frequency range of the oscillation, or the point of the pot from where the oscillation begin

(i don't know if i make myself clear, but i don't know how to explain it in another way)
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wackelpeter



Joined: May 05, 2013
Posts: 94
Location: germany
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PostPosted: Fri Jan 09, 2015 11:38 am    Post subject: Reply with quote  Mark this post and the followings unread

i can't remember exactly but i did some modification on R22 and R23... reducing them a bit... just try on one of them hooking another bigger resistor parallel on them to see how it changes so you don't have to desolder everything and can experiment whit it...
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space_zulu



Joined: Dec 15, 2014
Posts: 14
Location: france

PostPosted: Wed Feb 25, 2015 10:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Problem fixed ! sorry for the late repply, i had to raise R18 a LOT and fix a small short around a condenser.

if someone has the same issue i'm around 30k instead of 3,9k for R18
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