hello pierre,

the number of stages also affects the minimum delay time.
in the a188/1 manual you'll find a table with
the delay times of the different bbd-ic's.

some examples for the minimum delay times mentioned
in the bbd ic data sheets:
mn3006 ( 128 stages) = 0,32 ms
mn3209 ( 256 stages) = 0,64 ms
mn3204 ( 512 stages) = 1,28 ms
mn3207 (1024 stages) = 2,56 ms

you get these delay times with a hs-vco frequency of 400 khz,
which results in a 200 khz clocking rate for the bbd.
maybe you can even get shorter delays when the clock runs at
higher frequencies than 400 khz, but then you operate the bbd
outside of it's spec and this is not guaranteed to work properly.

from my point of view the bbd-ic's with 128, 256 and 512 stages
are best for flanging applications. the 1024 stages ic is
also a candidate for flangings, but imho the smaller bbd's
are better in this regard. the shorter the min delay time,
the higher is the "ringing" pitch of the flanging effect
(don't know how to say that in other words).
consequently the number of stages has a direct impact on
the flanging sound. my personal favorite is the 256 stages ic,
but that is a matter of taste. the 512 stages ic has a somewhat
harsher sound, which is good for more aggressive flangings.
also the overall usable delay range of the 512 stages ic
(without using a clock filter) seems to be better suited
for flangings than f.e. the ic with 128 stages.

chorus effects are another pair of shoes. for chorus you need
longer delay times than for flangers. probably the 1024 or
2048 stages ic's are a good solution for this, especially when
used in parallel with another (shorter) bbd.
thats why some chorus units had such a fat sound, there
is not only one delayed signal mixed with the original, there
are several delayed signals mixed with the original.
so a good chorus effect is harder to obtain than a good
flanging effect.

best wishes

ingo



--- In Doepfer_a100@yahoogroups.com , "Pierre Zeeman" <pierrezee@...>
wrote:

>
> Hi all,
>
> I know the number of stages in the bdd affects the delay time and

that more

> stages make for a longer delay, but does this work at the short end

as well

> i.e. with a smaller number of stages does the minimum delay time

get

> shorter as well I am primarily interested in the 188 for

flanger/chorus

> and effects, not long delays. Should I therefore get the chip with

the

> smallest number of stages Or are there other differences between

the

> various chips Reason I ask is that I thought Ingo's 512 stage

clips

> sounded the best, but that could be down to the way he modulated

them rather

> than anything else.
>
> t.i.a.
>
> rgds
>
> Pierre
>
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