[sdiy] Steiner filter mods

[HOSHUYAMA]

Hi Michael,

> It's interesting
> that you use 2 feedback paths here as this is what I found in the actual
> Synthacon I serviced a few years back.

I got to remember your schematic.  It inspired me to use the 2-path
feedback.  AC coupling of the pot leads to longer life span.
Thank you very much for the schematic.

Sam HOSHUYAMA


Michael Ruberto wrote:
>>
>>   http://houshu.at.webry.info/200511/img_1.gif
>>
>> Constant current source Q2 reduces common-mode gain of the
>> differential amplifier to almost zero, resulting in far less
>> CV feedthrough.
>>
> 
> hmmm this is very interesting as it sheds some light on another circuit 
> that's currently giving me a headache.
> 
>> Another modification is the output point to the buffer U1.
>> Response of the resonance pot is more like Korg MS20.
>>
>> I also used a diode limiter as Yves Usson.
>>
> 
> I have to say this is slick. I have my version of the filter on the 
> breadboard still and I'm gonna give this a try. On my VCF I have an FET 
> boosting the output signal from the circuit but the side effect is it's 
> also amplifying the gain changes from from resonance. It's interesting 
> that you use 2 feedback paths here as this is what I found in the actual 
> Synthacon I serviced a few years back.
> 
> M. A. Ruberto
> 
> 
> 
>