Doepfer

Hello --

I seem to be getting mixed reports about this, so I want to try to clarify my understanding of 
what the 4096 module is capable of, even though this has been brought up in previous 
exchanges: 

If the Karplus-Strong examples on the Doepfer webpage 
http://www.doepfer.de/A1881.htm
are done with a 2048-stage module, as it appears (am I right about that?), then is it not also 
possible to do similar plucking-style synthesis using the 4096?  

Or if, as it seems, one is limited to lower frequencies for plucking/resonance/Karplus-Strong 
sounds on the 4096, how low exactly in terms of Hz?

(I am interested in dirty sounds as well, but also curious about what the 4096 can do in terms 
of 'clean' K-S stuff.)

any guidance would be greatly appreciated
thanks
Ernst

Hi Ernst

> If the Karplus-Strong examples on the Doepfer webpage 
> http://www.doepfer.de/A1881.htm
> are done with a 2048-stage module, as it appears (am I right about that?), then is it not also 
> possible to do similar plucking-style synthesis using the 4096?  
I definitely would recommend a BBD with short delay times as possible 
for Karplus Strong synthesis - at least 2048, better 1024 or 512 steps.

You always can tune down a BBD, but never tune up above a certain rate.
The "distortions" on the signal handling when tuning down (with low 
clock frequencies) are not _that_ relevant with Karplus-Strong 
synthesis, because the sound itself is caused mostly by the shatter 
effect of the feedback.

Florian

> > Is the assumption that the A188-2 tapped BBD would be suitable for 
this
> > purpose, provided that you only use one tap, correct?


you should also take into account that the fastest possible clock
speed (or shortest delay) is also determined by the bbd chip itself.
the mn3011 in the a188/2 cannot be overclocked to the same
amount as other bbd's. for example, if an mn3011 would have
a 256 stages output, then the shortest delay time would not
be the same as for an a188/1 with 256 stages.
in other words, an a188/1 with 128, 256 or 512 stages will
serve you much better, if you want to do karplus strong synthesis.

best wishes

ingo

Is the assumption that the A188-2 tapped BBD would be suitable for this
purpose, provided that you only use one tap, correct? What about using two
or more taps, or would that amount to inviting destructive interference?

Cheers,

Silas

On 1/31/07, Florian Anwander <Florian.Anwander@consol.de> wrote:
>
>
> I definitely would recommend a BBD with short delay times as possible
> for Karplus Strong synthesis - at least 2048, better 1024 or 512 steps.
>


[Non-text portions of this message have been removed]

Hi Silas

> Is the assumption that the A188-2 tapped BBD would be suitable for this
> purpose, provided that you only use one tap, correct?
This sounds correct to me, but I don't have experiences with the A-188 
modules (I already own a Vestakaza DIG420, which is like the A188-1, and 
a ADA STD-1 which is like the A188-2).

> What about using two
> or more taps, or would that amount to inviting destructive interference?
The taps don't provide n*2 stages, so the results of using several taps 
would always be non harmonic in principle(!). But as long as the 
feedback is derived only from one tap, the other taps would not affect 
the Karplus-Strong sound at all, but only appear as a tuned kind of 
early reflection of the exciter sound.


Florian

Okay, so I'm trying to do Karplus-Strong synthesis now using a 188-2.  The main problem 
I'm having is in getting the right amount of feedback without getting overwhelming feedback.  
There is only the very very tiniest amount of distance on the knob between the two, meaning 
one has to make a very very very precise adjustment, barely barely turning the knob at all, to 
try to get the right amount of feedback.  This is extremely difficult, and actually in a live 
setting is impossible to get without going "too far".  

Has anyone else done KS synthesis using a 188-2?  Am I missing something?

I know that for "realistic" KS-synthesis I could filter the feedback, but I'm not necessarily 
interested in realism....

thanks,
Ernst

hello ernst,

the feedback-behaviour is caused by the bbd chip.
small bbd's with only a few stages (for example 128 or 256)
go into self-oscillation more smoothly, a bit like a vcf.
bbd's with more stages (for example more than 2048) go into
self-oscillation a lot faster, when a certain feedback
level is reached. that makes the feedback adjustment more
touchy on long bbd's. the a188/2 may have an output tap
for 396 stages, but after all it uses a bbd chip with
3328 stages, thats why the feedback behaviour is more harsh.

if you want better control of the feedback you could insert a
linear vca (a130) in the feedback path of the a188/2.
now you just need a voltage for the vca which is small enough
for your adjustment.

best wishes

ingo



--- In Doepfer_a100@yahoogroups.com, "ErnstKarel" <ekarel@...> wrote:
>
> Okay, so I'm trying to do Karplus-Strong synthesis now using a 188-
2.  The main problem 
> I'm having is in getting the right amount of feedback without 
getting overwhelming feedback.  
> There is only the very very tiniest amount of distance on the knob 
between the two, meaning 
> one has to make a very very very precise adjustment, barely barely 
turning the knob at all, to 
> try to get the right amount of feedback.  This is extremely 
difficult, and actually in a live 
> setting is impossible to get without going "too far".  
> 
> Has anyone else done KS synthesis using a 188-2?  Am I missing 
something?
> 
> I know that for "realistic" KS-synthesis I could filter the 
feedback, but I'm not necessarily 

> interested in realism....
> 
> thanks,
> Ernst
>

--- In Doepfer_a100@yahoogroups.com, "Silas Johansen" <sijodk@...> 
wrote:
>
> I don't have the A-188-2, but I've had similar problems with 
tweaking a
> filter to almost self-oscillate. The solution I found was to patch 
an A-176
> manual CV source into resonance CV and use the fine control on the 
CV-source
> to make exact adjustments. From the product page of the A-188 it 
seems that
> feedback cannot be CV-controlled, but the A-101-9 universal 
vactrol module
> might do the trick.
> 
> Cheers,
> 
> Silas


hello silas,

i'm not sure about the universal vactrol module.
it is a lot simpler and a lot more precise to use
a vca in the feedback loop of the a188.

best wishes

ingo

I don't have the A-188-2, but I've had similar problems with tweaking a
filter to almost self-oscillate. The solution I found was to patch an A-176
manual CV source into resonance CV and use the fine control on the CV-source
to make exact adjustments. From the product page of the A-188 it seems that
feedback cannot be CV-controlled, but the A-101-9 universal vactrol module
might do the trick.

Cheers,

Silas

On 4/8/07, ErnstKarel <ekarel@klingt.org> wrote:
>
>   Okay, so I'm trying to do Karplus-Strong synthesis now using a 188-2.
> The main problem
> I'm having is in getting the right amount of feedback without getting
> overwhelming feedback.
> There is only the very very tiniest amount of distance on the knob between
> the two, meaning
> one has to make a very very very precise adjustment, barely barely turning
> the knob at all, to
> try to get the right amount of feedback. This is extremely difficult, and
> actually in a live
> setting is impossible to get without going "too far".
>
> Has anyone else done KS synthesis using a 188-2? Am I missing something?
>
> I know that for "realistic" KS-synthesis I could filter the feedback, but
> I'm not necessarily
> interested in realism....
>
> thanks,
> Ernst
>
>  
>


[Non-text portions of this message have been removed]