MOTM

On Fri, 24 Jan 2003 media.nai@... wrote:

> Anyway, I never heard of a MOTM-880, have no idea what kind of EG a
> CS-80 has, or what Scott is doing.  Has he posted anything about it??

  I am back from NAMM, and can elaborate.  The CS-80 filter EG and the
MOTM-880 are a bit different, so I will describe both:

Stock CS-80 filter EG:

  The CS-80 filter EG is "bipolar".  This means the envelope does not have
to start or end at zero.  On the CS filter EG, there are the following
controls:

  Initial Level (IL): a slider that selects the starting voltage for the
envelope (front end of attack slope).  The range of this control is -5 to
0 volts.

  Attack level (AL): a slider that selects the peak voltage that the
attack slope must reach before transitioning to the decay slope.  The
range of this control is 0 to +5 volts.

  Attack Time (AT): a slider that selects the time to slope from IL to AL.
The range of this control is 1ms to 10 seconds.  One thing to note is the 
time varies with the distance between IL and AL.  The maximum time of 10 
seconds exists only when IL=-5, AL=+5.  All other times are proportional 
to the actual distance between endpoints.

  Decay Time (DT): a slider that selects the time to slope from AL to 
zero.  Nominally 1ms to 10s but as with AT the actual distance is a 
factor.

  Release time (RT): a slider that selects the time to slope from zero to 
IL after the gate (key) is no longer active.  Nominally 1ms to 10s range.

  Note that there is no sustain control.  On a CS-50/60/80 the filter EG 
sustain level is fixed at zero.

MOTM-880:

  Initial Level and Attack Level have the same action as in the CS filter 
EG, and the same ranges.  Each also can be set by a 0 to +V CV.

  Attack, Decay and Release Times are 3ms to 30 seconds and are also 
adjustable with 0 to +V CVs.

  Sustain Level:  The MOTM-880 has ajustable sustain from -5 to +5, also 
adjustable with a 0 to +V CV.

  Here is a diagram that should make things clear:
http://www.cs80.com/motm880/csadsr.gif

  Now the the MOTM-880's other features:

  There is a LIN/EXP switch to select the slope type.

  There is a 3-position switch to select the point at which a TRIG OUT
pulse is generated: when the attack peak is reached, when GATE IN goes 
inactive or when the end of the cycle is reached.

  There is a MANUAL GATE pushbutton.

  There is a bicolor LED showing the cycle status.  Yellow for GATE active
and in attack phase, green for GATE active in decay/sustain phase and red 
when in release phase; a brighter green or red (I think I can pull this 
stunt in PICcode) when a TRIG OUT is asserted and the LED is dark when the 
EG is idle.

  Normal and inverted envelope outputs.

> As much as I appreciate all of the ideas expressed in this thread, it
> supports a massive amount of features.  Imho, too many to fit into
> one module.   So I suggest the best approach would be a division of
> labor over several different modules.

  Oddly enough, the 880 is a 2U module.  My prototype undimensioned 
placement guide shows the layout:

http://www.cs80.com/motm880/motm880.gif

  The "Stooge notes" in the above image are for drilling purposes. ;)

  I am building three prototypes, and things like the LED colors are under 
PIC control, so if they need tweaked later, it is no problem.

Crow
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