Doepfer

Hi,


This is my first post here - I've been lurking around for a couple of
weeks, bascially since i got my 4-row a100 setup. I followed an
earlier advice of Dieter and got one of those cheap voltcraft scopes,
which has helped me a lot for understanding already most of the more
subtle features and quirks of the system.

I was wondering if anyone of you has been succesfull to get the a108
to work as an 'ordinary' 24 db filter with '24db' resonance. When I
hook up the 24db output to the feedback input, I can't get even close
to self-oscillation. Inserting a polarizing amp (138c, so as to be
able to change the phase) doesn't really do the job, but can get the
108 into some evil low freq oscillations when polarity is reversed.
Great fun all, but why can't I get resonance in 24db mode? I find the
48db resonance ok, but was curious to be able to get other, somewhat
milder resonance behaviors.

Cheers, Martin

hellol martin,
i get nice resonance sounds from the a108 when i keep
its audio input level knob up to about "3". this way
you can get nice resonance sounds in almost any filter
slope configuration...
regards,
Bakis.




--- marrtin606 <mvhecke@lorentz.leidenuniv.nl> wrote:

> Hi,
> 
> 
> This is my first post here - I've been lurking
> around for a couple of
> weeks, bascially since i got my 4-row a100 setup. I
> followed an
> earlier advice of Dieter and got one of those cheap
> voltcraft scopes,
> which has helped me a lot for understanding already
> most of the more
> subtle features and quirks of the system.
> 
> I was wondering if anyone of you has been succesfull
> to get the a108
> to work as an 'ordinary' 24 db filter with '24db'
> resonance. When I
> hook up the 24db output to the feedback input, I
> can't get even close
> to self-oscillation. Inserting a polarizing amp
> (138c, so as to be
> able to change the phase) doesn't really do the job,
> but can get the
> 108 into some evil low freq oscillations when
> polarity is reversed.
> Great fun all, but why can't I get resonance in 24db
> mode? I find the
> 48db resonance ok, but was curious to be able to get
> other, somewhat
> milder resonance behaviors.
> 
> Cheers, Martin
> 
> 
> 
> 


Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel-worlds-music.com
http://www.myspace.com/parallelworldsmusic
http://www.shimarecords.co.uk
http://www.rubber.gr
Athens-Greece

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I don't own a A108 but I'm quite sure for an "ordinary 24db filter" 
you will not use the Feedback In. Audio In and Audio Out plus the CV 
Ins that's it. The Feedback In is a special feature for "non-
ordinary" stuff. Regards, Ingo

--- In Doepfer_a100@yahoogroups.com, "marrtin606" <mvhecke@...> 
wrote:
>
> Hi,
> 
> 
> This is my first post here - I've been lurking around for a couple 
of
> weeks, bascially since i got my 4-row a100 setup. I followed an
> earlier advice of Dieter and got one of those cheap voltcraft 
scopes,
> which has helped me a lot for understanding already most of the 
more
> subtle features and quirks of the system.
> 
> I was wondering if anyone of you has been succesfull to get the 
a108
> to work as an 'ordinary' 24 db filter with '24db' resonance. When I
> hook up the 24db output to the feedback input, I can't get even 
close
> to self-oscillation. Inserting a polarizing amp (138c, so as to be
> able to change the phase) doesn't really do the job, but can get 
the
> 108 into some evil low freq oscillations when polarity is reversed.
> Great fun all, but why can't I get resonance in 24db mode? I find 
the
> 48db resonance ok, but was curious to be able to get other, 
somewhat

> milder resonance behaviors.
> 
> Cheers, Martin
>

Ingo is right on that.
you can get resonance sounds and self-oscillation on
the a108 without patching the res feedback
input(because, i think, by default the res feedback
input is internaly patched to the 24db filter output).
if you want, of course, you can patch the res input
with any of the filter outputs, for different
resonance behaviour.
regards,
Bakis.





--- ilanode <techmeier@web.de> wrote:

> I don't own a A108 but I'm quite sure for an
> "ordinary 24db filter" 
> you will not use the Feedback In. Audio In and Audio
> Out plus the CV 
> Ins that's it. The Feedback In is a special feature
> for "non-
> ordinary" stuff. Regards, Ingo
> 
> --- In Doepfer_a100@yahoogroups.com, "marrtin606"
> <mvhecke@...> 
> wrote:
> >
> > Hi,
> > 
> > 
> > This is my first post here - I've been lurking
> around for a couple 
> of
> > weeks, bascially since i got my 4-row a100 setup.
> I followed an
> > earlier advice of Dieter and got one of those
> cheap voltcraft 
> scopes,
> > which has helped me a lot for understanding
> already most of the 
> more
> > subtle features and quirks of the system.
> > 
> > I was wondering if anyone of you has been
> succesfull to get the 
> a108
> > to work as an 'ordinary' 24 db filter with '24db'
> resonance. When I
> > hook up the 24db output to the feedback input, I
> can't get even 
> close
> > to self-oscillation. Inserting a polarizing amp
> (138c, so as to be
> > able to change the phase) doesn't really do the
> job, but can get 
> the
> > 108 into some evil low freq oscillations when
> polarity is reversed.
> > Great fun all, but why can't I get resonance in
> 24db mode? I find 
> the
> > 48db resonance ok, but was curious to be able to
> get other, 
> somewhat
> > milder resonance behaviors.
> > 
> > Cheers, Martin
> >
> 
> 
> 
> 
> 
> 


Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel-worlds-music.com
http://www.myspace.com/parallelworldsmusic
http://www.shimarecords.co.uk
http://www.rubber.gr
Athens-Greece

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com

Dear members,

as many customers who ordered the A-188-1 module with 128 stages (MN3006)
did not want to wait for the revised module version we developed a small
adapter board (similar to those for the 4096 stages BBDs). Now we are able
to offer even the first version of the A-188-1 with 128 stages.

The revised version of the module (= third lot, suitable for all BBD
versions from 128 to 4096 stages without adapter boards) will arrive about
end of June 2006.

At the moment we are not able to deliver A-188-1 with 4096 stages as this
type of BBD circuits we had in stock (MN3005) is used up. The alternative
4096 stages BBD circuits (MN3205) we received are counterfied circuits with
1024 stages only (probably relabelled MN3207). But I hope that we will have
available new "real" BBD circuits with 4096 stages end of June when the
revised version of the A-188-1 module arrives. I'm waiting for a sample from
a new supplier to avoid the problems we had with the last one. But we have
to raise the price of the A-188-1 with 4096 stages for all new orders as the
(hopefully) "real" 4096 stages BBDs are much more expensive.

Even the price of the A-188-1 module with 256 stages has the be increased a
bit as the new MN3209 are a bit more expensive than the first lot. The
prices for the other versions (128, 512, 1024, 2048 stages) remain
unchanged.

Best wishes
Dieter Doepfer

Dear Ingo, Bakis,

you're of course right I don't need the feedback to get some form of
resonance - but the point was to understand why i couldn;t get
resonance using only 4 poles.

I'm pretty sure the feedback is internally patched to the 48db - 
apart from the manual and schematics suggesting this, you can also
try this by directly patching the 48db out to the feedback in: you get
just the same as when nothing is plugged into the feedback in.

> if you want, of course, you can patch the res input
> with any of the filter outputs, for different
> resonance behaviour.
> regards,
> Bakis.
> 

That was precisely what i was trying to do, but didn't get much
resonance. And that surprised me, because 4 poles/24db should be
sufficient for that.

I found out now that if I amplify the 24db signal a bit before feeding
back (with a vca or externally), I also can get into resonance using
only 4 poles. I'm still curious to hear what other 108 users find!

Cheers Martin

Martin,

there is a trimming potentiometer on the A-108 board that is used to adjust
the resonance so that self-oscillation just appears at the full clockwise
position of the resonance control. This trimming potentiometer is adjusted
for the default feedback (48dB output). If another output is used for
feedback the levels and phase relations are a bit different and you obtain a
different resonance behaviour as the setting of the trimming  potentiometer
is optimized for the default 48dB feedback. This is why you have to amplify
the signal. You could try to re-adjust the trimming potentiometer for the
24dB feedback loop but then the setting is not optimal for the default 48dB
feedback loop.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von marrtin606
> Gesendet: Mittwoch, 31. Mai 2006 21:01
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: resonance for a108 when feeding 24db output
> into feedback input?
>
>
> Dear Ingo, Bakis,
>
> you're of course right I don't need the feedback to get some form of
> resonance - but the point was to understand why i couldn;t get
> resonance using only 4 poles.
>
> I'm pretty sure the feedback is internally patched to the 48db -
> apart from the manual and schematics suggesting this, you can also
> try this by directly patching the 48db out to the feedback in: you get
> just the same as when nothing is plugged into the feedback in.
>
> > if you want, of course, you can patch the res input
> > with any of the filter outputs, for different
> > resonance behaviour.
> > regards,
> > Bakis.
> >
>
> That was precisely what i was trying to do, but didn't get much
> resonance. And that surprised me, because 4 poles/24db should be
> sufficient for that.
>
> I found out now that if I amplify the 24db signal a bit before feeding
> back (with a vca or externally), I also can get into resonance using
> only 4 poles. I'm still curious to hear what other 108 users find!
>
> Cheers Martin
>
>
>
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Dear Dieter,

Thanks, found the pot (p8), and am playing around to find setting(s)
I like. It's an awesome filter by the way.

Cheers Martin


>
> Martin,
> 
> there is a trimming potentiometer on the A-108 board that is used to
adjust
> the resonance so that self-oscillation just appears at the full
clockwise
> position of the resonance control. This trimming potentiometer is
adjusted
> for the default feedback (48dB output). If another output is used for
> feedback the levels and phase relations are a bit different and you
obtain a
> different resonance behaviour as the setting of the trimming 
potentiometer
> is optimized for the default 48dB feedback. This is why you have to
amplify
> the signal. You could try to re-adjust the trimming potentiometer
for the
> 24dB feedback loop but then the setting is not optimal for the
default 48dB
> feedback loop.
> 
> Best wishes
> Dieter Doepfer
> 
> > -----Ursprüngliche Nachricht-----
> > Von: Doepfer_a100@yahoogroups.com
> > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von marrtin606
> > Gesendet: Mittwoch, 31. Mai 2006 21:01
> > An: Doepfer_a100@yahoogroups.com
> > Betreff: [Doepfer_a100] Re: resonance for a108 when feeding 24db
output

> > into feedback input?
> >
> >
> > Dear Ingo, Bakis,
> >
> > you're of course right I don't need the feedback to get some form of
> > resonance - but the point was to understand why i couldn;t get
> > resonance using only 4 poles.
> >
> > I'm pretty sure the feedback is internally patched to the 48db -
> > apart from the manual and schematics suggesting this, you can also
> > try this by directly patching the 48db out to the feedback in: you get
> > just the same as when nothing is plugged into the feedback in.
> >
> > > if you want, of course, you can patch the res input
> > > with any of the filter outputs, for different
> > > resonance behaviour.
> > > regards,
> > > Bakis.
> > >
> >
> > That was precisely what i was trying to do, but didn't get much
> > resonance. And that surprised me, because 4 poles/24db should be
> > sufficient for that.
> >
> > I found out now that if I amplify the 24db signal a bit before feeding
> > back (with a vca or externally), I also can get into resonance using
> > only 4 poles. I'm still curious to hear what other 108 users find!
> >
> > Cheers Martin
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
>