Hello Tim, the wiper of my prototype is connected to pin 2 of the
LM324 and an 100pF cap! Actually I thought the prototype would be
technically the same as the A101-2 in production. (If Dieter "sneaks",
it reads "Pr. 2" on the back of the frontpanel).

To summerize the results: Now the self osc. can be dialed in and is
absolutly not dominating the overall sound since the original signal
is always in the foreground. Thus you can no longer overdrive the
input signal and have a dominating self osc. since you have to dial
down the input signal to alter the signal/self osc. ratio in favor of
the later. In my opinion absolutely no problem for I think the module
now much more versatile than before. It will only self. osc. in the LP
mode.

BTW usually, even though not always, a TL074 is prefered over an
LM324, do you see any reason why the LM324 has been choosen for the LPG

Again, your contribtions are highly appreciated! Best, Ingo


--- In Doepfer_a100@yahoogroups.com , "Tim Stinchcombe" <timothy@...>
wrote:

>
> Hi Ingo,
>
> > Hello Tim, thank you very much for your efforts. Highly appreciated.
>
> My pleasure!
>
> > Thanks to your suggestion and my solder sucker I've swapped the B50K
> > pot for a C50K in a fly. The result is much more to my liking.
>
> Great, sounds like we're moving in the right direction!
>
> > I still like to give your 2nd mod a try but I'm not sure wether I
> get
> > it.
>
> OK, but...
>
> > Even worse my A101-2 is a prototype thus there are no part numbers
> > on the board.
>
> ...thus your module *might* be slightly different!
>
> > Pls verify if I've understood how to proceed:
> > I'm going to link the res. pots wiper (= 2nd pin i.e. the one in the
> > middle)
> <snip>
>
> As you look at the pot from the front, simply short the middle pin to
> the right-hand end - if your module *is* as the schematic I have,
> this end should go to the 47k resistor, and pin 2 on the amplifier
> chip (LM324), and a 100p cap. If the wiper is already connected to
> this point, then it looks like it may have got changed for the
> production version (it is a fairly subtle change after all!) - the
> other end of the 47k should go to ground, and you *don't* want to
> connect the wiper there! If you're still not sure, get back to me.
>
> I'm just about finished writing up some slightly more detailed notes,
> mostly for my own benefit, but I will send a copy to Dieter so that
> he can see what I have done/am suggesting.
>
> As I mentioned before it is possibly that this change will move the
> whole resonance peak down to a lower pot setting - if this is
> happening you should detect that the resonance *decreases* again as
> the pot is rotated further clockwise from some given point. If you
> think this is happening let me know, and I can probably make a
> suggestion on how to cure it (basically replacing that 47k with a
> slightly larger value).
>
> Good luck,
>
> Tim
>