Ingo,

you are right. My last statement was a bit wrong. The high speed VCO goes up
to 200 kHz, but the resulting BBD clock is 100kHz. The reason for the half
frequency is the required 2-phase clock for the BBD chip (2 clock signals
with 50% duty cycle and opposite polarity). In our circuit this is realized
with a simple flip-flop that halves the incoming frequency (200kHz HSVCO
frequency -> 100kHz BBD clock). In other circuits even inverters or special
BBD driver circuits are used.

So the HCVSO goes up to 200kHz, resulting in 100kHz BBD clock and
consequently 10.24ms delay time.

My comment to exact 1V/Oct high speed VCO:

To speak the truth we have problems to develop an affordable high speed VCO
that goes up to the desired frequencies (at least 200kHz for BBD and digital
delay applications or 1MHz for SC-filter). We tried several designs:
lin-to-log converter with following precision linear VCO, current controlled
VCO with logarithmic current source, "normal" VCO with PLL and some more.
Each solution has it's advantages and disadvantages. The best result
(concernig 1V/Oct precision) is the standard audio VCO with a PLL but it has
a very bad response time and cannot be used for fast changes of the delay
time (which is essential from my point of view). So we will pick up Florians
suggestion and put a so-so 1V/Oct HSVCO into the BBD module but offer an
external clock input (normalled to the internal HSVCO) that enables to drive
the unit from an external precision HSVCO (I hope we will be able to design
a better - but even more expensive - HSVCO in the near future).

My comment to Karplus/Strong and similar:

For these applications I'd prefer the announced universal AD/processor/DA
module. Beside the much better audio quality this module will allow to
adjust the memory length (this is fixed for the BBD module zu 2048).
Consequently the delay time is not only determined by the clock frequency
(HSVCO) but even by the (adjustable) memory length. At the moment we prefer
the adjustment of the memory length with up/down buttons (e.g.
2/4/8/16/32/64/128 ..... 1M) and a 3-digit LED display (the decimal points
could indicate "kilo" and "mega").

Best wishes
Dieter Doepfer

b.t.w. The SC filter prototype working as well. To speak the truth: it's not
very exciting from my point of view. Just a chaste, clean filter having not
very much character to my estimation. Maybe I use to often the A-106-1,
A-107 and A-124 ...
I hope I will find the time to make some MP3's soon.

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von selfoscillate
> Gesendet: Montag, 17. Oktober 2005 14:29
> An: Doepfer_a100@yahoogroups.com
> Betreff: 1 Re: BBD module first mp3 sound clips!!!
>
>
>
> hello dieter,
>
> please correct me if i'm wrong, but with the clock at 200 khz
> the minimum delay time should be around 5 ms.
> at least this is what the old panasonic data sheets say.
>
> regarding the delay time knob, i'd prefer that the
> delay time decreases when the cv increases, especially
> when an 1v/oct input is available. would be better for
> karplus-strong-synthesis.
>
> best wishes
>
> ingo
>
>
>
> --- In Doepfer_a100@yahoogroups.com , "Dieter Doepfer" <hardware@d...>
> wrote:
> >
> > Florian,
> >
> > the shortest possible delay time is calculated from these facts:
> >
> > max. clock frequency of the BBD used in the module (from data
> sheet): 200kHz
> > BBD length: 2048
> > -> shortest delay time = 10 ms
> >
> > Maybe we could offer the module even with a 1024 or 512 BBD
> circuits to
> > obtain 5ms or 2.5ms shortest delay. I will see if the BBD
> manufacturer
> > offers pin-compatible BBDs with 1024 or 512 stages.
> >
> > I also will see what happens if the BBD is clocked with a frequency
> beyond
> > 200kHz. Maybe the data sheet is conservative and frequencies beyond
> 200kHz
> > are possible.
> >
> >
> > The first two examples are simply the original signals used in the
> following
> > examples to know and hear which audio source was used. I think it
> is useful
> > the know the unprocessed audio signal too.
> >
> > Best wishes
> > Dieter Doepfer
> >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Doepfer_a100@yahoogroups.com
> > > [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von Florian
> Anwander
> > > Gesendet: Montag, 17. Oktober 2005 11:16
> > > An: Doepfer_a100@yahoogroups.com
> > > Betreff: Re: 1 BBD module first mp3 sound clips!!!
> > >
> > >
> > > Hi
> > >
> > > In general the sound makes me looking happily forward for this
> module.
> > >
> > > But....
> > >
> > > www.doepfer.de/A100_BBD.htm says:
> > > ---------------snip--------------
> > > For both audio signals a standard flanger appication was made
> (triangle
> > > output of a LFO is used to control the clock CV input of the BBD
> module,
> > > short delay time/high clock rate, medium resonance):
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^!!!!!!!!!!!!!!!!!!!!!!!!
> > > * BBD_Flange_LFO_1.mp3
> > > * BBD_Flange_LFO_2.mp3
> > > ---------------snip--------------
> > >
> > > If the delaytimes in these exmples these are the shortest possible
> > > delaytimes, it would be very unsatisfying. I would need MUCH(!)
> shorter
> > > ones! For classic Flanging and for envelope controlled notch
> filter
> > > stuff, and definitely for Karplus Strong Synthesis or similar.
> > >
> > > The shortest delaytime corresponds to the highest possible
> frequency of
> > > a bbd-notchfilter or the highest possible frequency of an karplus
> strong
> > > oscillator.
> > >
> > >
> > > And btw. I do not understand, what is the role of the BBD in the
> first
> > > two expamples
> > >
> > > BBD_Source_1.mp3: a short sample recorded with the A-112
> > > BBD_Source_2.mp3: an 8 note sequence made with A-100 modules (A-
> 110
> > > + A-105 + A-140 controlled by a MAQ16/3)
> > >
> > >
> > >
> > > Florian
> > >
> > > Bakis Sirros wrote:
> > >
> > > > dieter says:
> > > > "the very first sound examples of the BBD module are
> > > > now available. As the page of this module is very
> > > > preliminary so far there is no link from the other
> > > > pages of our web site.
> > > > Here is the (hidden) link:
> > > > www.doepfer.de/A100_BBD.htm.
> > > > Even the module number is not yet fixed."
> > > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>