Doepfer

hi joe,
very...complicated,indeed....
right,but then you would need too many modules for
doing what you could do with only one module.so,this
module,too,has a purpose.
by the way,the two bottom rows of jacks in the a166
are not placebo!they are two trigger inverters.
bakis.


--- Joe Buechler <buechlerjoe@toadmail.com> 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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