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steiner_vcf troubles

2005-03-28 by marcel01011

hi, i've recently built the steiner vcf; but it hasn't been working
properly. when i first tested it i connected the power backwards, and
now when i use it it constantly oscillates even with resonance turned
completely down. the sound is like a standard feedbacked signal, loud,
and high-pitched. when i turn the cutoff i can heare some filtering
through the screaming feedback though.
The tl071 is still fine, and i've checked+reflowed the solder joints;
my question is, any of you smart people know where the problem most
likely would be/ where i should start troubleshooting?
should i replace (test?) transistors, caps?

any help is welcome

cheers, marcel

Re: steiner_vcf troubles

2005-03-28 by sasami@hotkey.net.au

Were the specified transistors used? It sounds like you have too much gain
in the output stage. Try replacing the 1k pot with something higher and see
if it makes a difference.

Ken

Show quoted textHide quoted text

>hi, i've recently built the steiner vcf; but it hasn't been working
>properly. when i first tested it i connected the power backwards, and
>now when i use it it constantly oscillates even with resonance turned
>completely down. the sound is like a standard feedbacked signal, loud,
>and high-pitched. when i turn the cutoff i can heare some filtering
>through the screaming feedback though.
>The tl071 is still fine, and i've checked+reflowed the solder joints;
>my question is, any of you smart people know where the problem most
>likely would be/ where i should start troubleshooting?
>should i replace (test?) transistors, caps?
>
>any help is welcome
>
>cheers, marcel

_______________________________________________________________________
Ken Stone sasami@... or sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: steiner_vcf troubles

2005-03-29 by marcel01011

Hi, thanks for the reply,

yup, i used the 2n2222 & 2n2907; any chance i fried them when i
reversed the power supply?
I'll check it like you suggested with a higher res pot.

When this "works" (other res pot); it means i have too much gain in
the output stage, yeah? which component can be held responsible for
this? or am i jumping ahead too fast now?

thanks, marcel

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--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> Were the specified transistors used? It sounds like you have too
much gain
> in the output stage. Try replacing the 1k pot with something
higher and see
> if it makes a difference.
>
> Ken
>
> >hi, i've recently built the steiner vcf; but it hasn't been
working
> >properly. when i first tested it i connected the power backwards,
and
> >now when i use it it constantly oscillates even with resonance
turned
> >completely down. the sound is like a standard feedbacked signal,
loud,
> >and high-pitched. when i turn the cutoff i can heare some
filtering
> >through the screaming feedback though.
> >The tl071 is still fine, and i've checked+reflowed the solder
joints;
> >my question is, any of you smart people know where the problem
most
> >likely would be/ where i should start troubleshooting?
> >should i replace (test?) transistors, caps?
> >
> >any help is welcome
> >
> >cheers, marcel
>
_____________________________________________________________________
__
> Ken Stone sasami@h... or sasami@c...
> Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/>

Re: steiner_vcf troubles

2007-05-19 by funkfumes

Marcel,

Did you get your Steiner VCF working in the end?
I think I have the exact same problem as you, though I didn't connect
the power the wrong way around to begin with.
It just keeps resonating...
Any tips?

Evan.

--- In cgs_synth@yahoogroups.com, "marcel01011" <marcel_binary@...>
wrote:

Show quoted textHide quoted text

>
>
> hi, i've recently built the steiner vcf; but it hasn't been working
> properly. when i first tested it i connected the power backwards,

and

> now when i use it it constantly oscillates even with resonance

turned

> completely down. the sound is like a standard feedbacked signal,

loud,

> and high-pitched. when i turn the cutoff i can heare some filtering
> through the screaming feedback though.
> The tl071 is still fine, and i've checked+reflowed the solder

joints;

> my question is, any of you smart people know where the problem most
> likely would be/ where i should start troubleshooting?
> should i replace (test?) transistors, caps?
>
> any help is welcome
>
> cheers, marcel
>

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steiner_vcf troubles

steiner_vcf troubles

Re: steiner_vcf troubles

Re: steiner_vcf troubles

Re: steiner_vcf troubles

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