Doepfer

Hi Bakis
> by the way,the two bottom rows of jacks in the a166
> are not placebo!they are two trigger inverters.
> bakis.

Right you are! I haven't looked at the front panel layout since 
the A166 went into production. The earlier front panel illustration on 
the Doepfer web site used to have a row of output jacks below the NOT 
or inverter function, for logical false (or low). these were just 
dummy jacks - zero volts - as far as I can tell. Not sure where that 
space went to, I think the triple output jacks for the logic 
functions have been added also.

Anyway, my mistake, not keeping up with the news.

Joe

> 
> 
> --- Joe Buechler <buechlerjoe@t...> wrote:
> > I thought I'd describe how do a min/max function and
> > other comparison 
> > logic using attenuation/offset and the A150 VC
> > switch.
> > 
> > The most simple single-input comparison is to test
> > whether a voltage 
> > is positive or negative, i.e. X > 0. 
> > 
> > Patch a CV source or other fixed voltage to an A138a
> > mixer channel, 
> > turn all the mixer knobs fully clockwise, and patch
> > the mixer output 
> > to the A150's CV input jack. Adjust the CV source
> > until the A150 is 
> > right at the switching threshold (both LEDs dimly
> > lit).
> > 
> > Now patch your unknown voltage, lets call it X, to a
> > second channel on 
> > the mixer. If X is positive, the switch will close,
> > and if X is 
> > negative, the switch will open. That completes the X
> > > 0 patch.
> > 
> > You can use this to create an Absolute Value
> > function:
> > ABS(X) = if X > 0 then X else -X
> > Use the voltage inverter module to patch X and -X to
> > the A150's I/O1 
> > and I/O2 jacks. The O/I output is the Absolute Value
> > function.
> > 
> > You could feed random LFOs or other combined signals
> > to the ABS 
> > function to get different variations of these
> > signals. Feed the output 
> > to the A156 if you like, it's always a positive
> > voltage.
> > 
> > To do a two input comparison, or compare two unknown
> > voltages with 
> > each other, just patch the second voltage Y through
> > the voltage 
> > inverter to a third channel on the mixer. Now you're
> > testing 
> > X - Y > 0 which is the same thing as X > Y.
> > 
> > Now you can create the Min and Max functions:
> > Max(X,Y) = if X > Y then X else Y
> > Min(X,Y) = if X > Y then Y else X
> > Just patch the X and Y voltages to the A150's I/O1
> > and I/O2 jacks. The 
> > O/I output jack will be the Min or Max function.
> > 
> > There's uses for an X > Y comparison other than the
> > Min/Max functions. 
> > For example, you could use a sample and hold to
> > compare each 
> > successive note CV to the previous not, and have
> > different sounds for 
> > ascending and descending musical passages.
> > 
> > You can also create keyboard zones with a variable
> > split point, 
> > something digital synths can't usually do. This is
> > useful, for 
> > example, in a guitar patch, where the transition
> > from wound-string to 
> > flat-string sounds isn't at a fixed note, like it is
> > on a piano.
> > 
> > To create Dieter's three-input Min/Max function,
> > it's a simple matter 
> > to cascade two-input Min/Max functions in tandem:
> > Max(X,Y,Z) = Max(Max(X,Y),Z) (same for Min)
> > 
> > Since the VC Switch and Voltage Inverter are dual
> > modules, all you 
> > need is a second mixer to create the second Min/Max
> > function.
> > 
> > Give these a try, it'll give you an idea whether the
> > proposed Min/Max 
> > module will be useful to you. Personally, I would
> > rather have a module 
> > with just the comparison logic, it would be more
> > versatile. In fact, I 
> > think it was a big mistake to leave out comparison
> > logic on the A166 
> > Boolean Logic module, which could have been included
> > instead of those 
> > stupid placebo jacks on the bottom.
> > 
> > Joe
> > 
> > 
> 
> 
> =====
> synthfreak(parallel worlds)
> athens-greece
> [Doepfer_a100] group owner
> 
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