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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Noisy Resonance Pot @ Steiner VCF
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tömbszelence



Joined: Aug 12, 2012
Posts: 2
Location: Hungary

PostPosted: Sun Aug 12, 2012 2:12 am    Post subject: Noisy Resonance Pot @ Steiner VCF
Subject description: steiner res pot
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Hi!

The resonance pot makes some white noise like sound (not cracking) when i adjust it. I've tried it with some different pots and it still does it. The DC voltage is 2.06v around the emitter of the 2N3904 which seems to be fine according to previous debug threads. The 10uF electrolyte seems to be working fine according to my capacitance meter and it is connected to the pads around it.

Is it possible that i just messed up the order of the wires of the resonance pot?

(btw i used 2N3904 and 2N3906 trannies, the trannies in the filter core were matched within 1% @ 150hfe, and the amplifier pair of transistors had a gain of 150(3904) and 50(3906), it seems to react well to both of the freq and res pot except it can't reach self-oscillation)
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andrewF



Joined: Dec 29, 2006
Posts: 1174
Location: australia
Audio files: 4

PostPosted: Sun Aug 12, 2012 6:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi welcome to e-m

The noisy res pot on the Steiner is very common, the fact you have it means you probably wired it up correctly.
These threads discuss ways to get rid of the noise, if it bothers you

http://electro-music.com/forum/viewtopic.php?highlight=steiner&t=48989

http://electro-music.com/forum/viewtopic.php?highlight=resonance&t=34615
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tömbszelence



Joined: Aug 12, 2012
Posts: 2
Location: Hungary

PostPosted: Mon Aug 13, 2012 10:39 am    Post subject: Reply with quote  Mark this post and the followings unread

andrewF wrote:
Hi welcome to e-m

The noisy res pot on the Steiner is very common, the fact you have it means you probably wired it up correctly.
These threads discuss ways to get rid of the noise, if it bothers you

http://electro-music.com/forum/viewtopic.php?highlight=steiner&t=48989

http://electro-music.com/forum/viewtopic.php?highlight=resonance&t=34615


Thanks! The noise does not really bother me, i just thought that it could indicate some soldering fails or something.

Now i just have to do some things to tweak the response of the frequency pot. And add a CV voltage divider pot, i don't even know why it is not mentioned on the site, it seems like a pretty essential part.
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Abby Normal



Joined: Feb 20, 2010
Posts: 66
Location: USA
Audio files: 2

PostPosted: Sun Nov 18, 2012 10:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Just wanted to document that the mod by Ken Stone in Andrew's second link just cured the noisey res pot on my Steiner Rev 1 PCB. I used a 10uF, 35V electrolytic cap.

Here's the quote from Ken Stone:

The solution that supposedly works is to wire the 1k pot outer terminals
into the circuit instead of an outer and the wiper. One then adds a
capacitor between the wiper and one end. The result is that the DC passes
through the 1k as required, and the wiper only ever sees AC.
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