Hello Guy,

totally impressive work !

You find my comments written inline.

Best wishes
Dieter Doepfer

__________________________________________________________________

Doepfer Musikelektronik GmbH
based in Graefelfing/Germany
registered in Munich/Germany, commercial registry HRB 97 399
CEO's: Sibille Heller, Dieter Doepfer
European VAT ID No. DE129329318
website: www.doepfer.com
__________________________________________________________________

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von Guy
> Gesendet: Mittwoch, 30. Juni 2010 14:20
> An: Doepfer_a100@yahoogroups.com
> Betreff: 1 DIY Doepfer Synth | first panel
>
>
> Hi,
>
> Here's a few photos of my Doepfer DIY panel, Serge-style.
>
> It's a two-module panel, but only one DIY module is wired up for now.
> I've added a AC-coupled audio mixer (CGS04), a DC mixer (CGS04),
> Manual Gate and Voltage Source.
>
> As can be seen, there's no decent casing yet... that always comes
> last. :-)
>
> It works well, but I still need to tweak a few values here and
> there... Linear FM is "to deep", VCA goes to overdrive when fully
> AM'ed (though with a nicely, tubey sounding distortion)

it should be no problem to adjust the behaviour of the linear FM and the VCA
by changing the values of some resistors. You simply have to add a seriel
resistor at the corresponding CV input to reduce the sensitivity (or use the
summing input with another resistor value).

> not very happy with the way the Slew Limiter works.

I'm surprised to hear that. The slew limiter works like all slew limiters,
nothing but a capacitor buffered by an operational amplifier that is charged
via a variable resistor (potentiometer with logarithmic scale in the range
1M...5M recommended). It's exactly the same curcuit as for the upper unit of
the A-170.

> Lopass cutoff has a bit of a "knee" in the higher frequencies, though I

reckon

> there's nothing I can do about that.

Right. The 12dB VCF is made simply with two VCAs of the SSM2164. There is
not much that can be changed. Only the quad opamp right from the SSM2164
(TL074) could be replaced by another compatible opamp with different
frequency response.

> But overall it sounds very nice. Warm & tender, or gritty & brutal.

Thank's. I like the high pass very much (with moderate resonance).

> Can't wait to see what Dieter is going to come up with for the
> expansion module...

in any case noise, random voltage, ring modulator, S&H, VCLFO with reset
will be included. But we also think about other additions (24dB low pass,
BBD, wave shaper ...)

> http://www.guyd2.com/stuff/DoepfDiy_front.jpg
> http://www.guyd2.com/stuff/DoepfDiy_detail.jpg
> http://www.guyd2.com/stuff/DoepfDiy_wired.jpg
>
> Wiring is a bit messy, but that's hard to avoid with IDC
> connectors. Fortunately there's no crosstalk or bleedthrough though.
>
>
> cheers,
> _guy
>
>
>
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