[sdiy] Steiner filter mods

[fmg]

HOSHUYAMA wrote:
> 
> Hello List,
> 
> I also built a Steiner-style filter with simple modifications.
> 
> Schematic:
> 
>   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.
> 
> 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.
> 
> Sam HOSHUYAMA
> Saitama, JAPAN

Sam,

Shouldn't gate of Q2 be directly to -15V?
I don't understand how Q2 keeps current constant as is. Was a
drawing mistake? I'm confused.

Fabio
{I want an anatomical zoom
/Soda Stereo}
.