[sdiy] SVF resonance overdrive problem

[Paul Perry]

As I said before, i don't believe a 3080 or other OTA
will be happy wiht the output just floating around.
See, for example, this
http://hem.bredband.net/bersyn/VCA/ca3080%20vca%201.htm
from one of the masters :D Note the 47K to ground.
Since the OTA is a current amplifier, if you want a voltage from it,
you have to run the output current thru a resistor to develop it.

The buffers & diode inputs aren't the main problem.

paul perry Melbourne Australia

----- Original Message ----- 
>Unfortunley i do not have a schematic, it's based on
>this circuit
>http://www.synthdiy.com/show/getfile.asp?get=23
>I've used LM13700s with the + input grounded, leaving
>buffers and linearization diode inputs unused. Could
>that be a problem?

Karl

--- Andrew Simper <andy-list at vellocet.com> skrev:

> Which circuit are you basing your SVF on? Can you
> please post a link to the
> schematic here? Have you checked the SEM SVF
> schematic
> (http://www.synthfool.com/schematics/sem.gif)?
> Forget about the ARP one if
> you want lower distortion - it actually drives more
> and you loose resonance
> more quickly, I didn't read you're email properly
> last night when I was
> tired. The regular SVF like the SEM keep strong
> resonance no matter what
> input level you have.
>
> Andrew
>
> -----Original Message-----
> From: Karl Ekdahl [mailto:elektrodwarf at yahoo.se]
> Sent: 11 December 2006 19:44
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] SVF resonance overdrive problem
>
> Hi list,
>
> i've built a OTA-based SVF whose resonance distorts
> heavily if i have to
> high input-volume. The problem is that "to high" is
> something like >20mVpp
> so that won't do. Can anyone give me a hint on
> what's wrong, is this a
> common problem with SVFs?
>
> Karl
>
>
>
>
>
>
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>






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