MOTM 100 experience

Dan Higdon hdan at
Mon May 11 23:24:53 CEST 1998

I got home Friday to discover my brand-new MOTM 100 (noise+s/h)
waiting for me.  This one was packed just as soundly as the last,
with every part neatly bagged and labeled.  If you remember the
raving about the first MOTM (110 - Ring+VCA), all the same
applies to this one.  These modules are TOP quality packaging
and materials.  Well worth the extra expense - I just love soldering
on plated-through holes.

I sat down Sunday afternoon, and after a pleasant 3-4 hours
(I work slowly, er, deliberately :-) I had finished my second MOTM

How does it sound?  The noise is very noisy, but in a good way.
My only other noise source was a badly hacked up version of
the EN white->pink->random circuit, which this one seems to
be loosely based on.  Compared to my old noise source, this
one is great - less "sputtery", and the random actually works.  :-)

The vibrato is a very interesting circuit.  Paul has included a
jumper block to allow you to select one of two operating modes:

1 Vibrato varies from a 7hz sine wave towards random noise
    depending on the setting of the vibrato knob.  You can move
    "towards" the pure sine wave, or away from it for a less mechanical
    sound.  I haven't had enough time to play with this one, but I
    think I'll leave mine set on this setting.
2 "Boing" mode feeds the s/h internal clock pulse into the
    7hz sine wave (really a highly resonant filter), causing it
    to go into a damped oscillation mode.  The less "vibrato"
    you select, the faster the sound decays.  This mode is
    interesting from a "wierd sounds" perspective, and can
    make some interesting oscillations when you ballance
    the vibrato control and clock tick to make a pulsing
    continuous 7hz signal.

If I had two of these, I would *definitely* set the second one on 
boing mode.  As it is, I've seriously considered drilling a hole in
the panel to provide a switch, although I'm reluctant to drill such
a beautiful panel!

The second part of this module is the Sample and Hold unit.
The s/h module has a signal input (normalled to white noise),
a clock input (normalled to the clock generator), and an
output.  A knob scales the sampled input to help control
correlation of random numbers, or restrict the arpeggiation
effect of a sampled LFO.  Another knob controls the built
in clock' oscillation.  The range on this seems very wide.
I haven't measured it, but at the extreme range you get
CVs at a rate about like "R2D2 computer sounds".  At
the mid point, it seems about 1-2hz, and it gets rather slow
at the slowest range.  I haven't had time to really hammer this
one, but the manual says the the s+h has a very low droop
rate.  In my tests, I only used the higher-speed modes, and
I didn't notice any problems.  As I have more time, I'll actually
check this out more.

This s/h module also has a switch to go into "track and hold",
which basically lets you monitor a CV when the clock is
high, and freezes the CV when the clock goes low.  I haven't
had any time to play with this, but it sounds like a neat option.

This module is great fun to play around with, and you can
generate all sorts of semi-random and arpeggio-like scales
with appropriate inputs.  I personally have never had the
chance to play with a proper sample and hold module before,
and this one seems like loads of fun.

All in all, I was really looking forward to this module, and I
am not disappointed in the least.  Paul has really done
something cool here.  These kits let you build attractive
and useful modules for less than you might expect to
buy comparable modules (yes I know about doepfer).

My *only* complaints are that there is not a panel switch for
the two vibrato modes (easily remedied, and realistically
most people probably won't use both modes), and there is
no clock out jack.  I know I can fix both of these shortcomings
trivially, but IMHO I would have liked to have these options.

So - If what Paul says about module #3 being a  preamp
+env follower+moog filter is true, I will be in Analog Heaven!
(pun intended)

hdan at
"Throwing fire at the sun"

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