Archive of the former Yahoo!Groups mailing list: MOTM

Some my recall ~ 1yr ago there was discussion about a MOTM-102 Noise/S&H
module (some wanted just the S&H part).

I am in the process of finishing the 'design in my head' (well, also the
schematic!) and this is where the module is right now. The intent of the
module is two-fold:

a) this will ∗replace∗ the MOTM-101 as parts are getting hard/expensive to
find looking out 2-5yrs from now.
b) I want to add more 'bells & whistles' and take advantage of SMT ICs
available

To get this out of the way early on: this is a digital module :) It uses a
60Mhz 32-bit ARM uP connected to serial ADC and DACs. But let's check out
the current feature list:

a) I am dropping the Vibrato section of the '101, and replacing it with a
tunable noise source (there are still White/Pink/Slow Random)
----- Now, should I ∗drop∗ Slow Random, and instead have Internal Clock Out?
I am leaning this way myself as this is missing from the '101. See later
features).

b) The current single in/out analog S&H circuitry is replaced with a
4-section output (cascade, also called an ASR). The S&H function is through
a 14-bit A/D D/A path, meaning no "droop".

c) the time delay ∗between∗ taps can be set by a panel pot from 0 (typical
ASR to 256). So, at maximum, there are 1024 clock between the input being
sampled, and that voltage appearing on the output of Tap #4.

d) early calculations have indicated that the S&H code can be clock at a
∗minimum∗ of 1Khz. So, at max tap setting, you can get a 1sec delay. Now,
this is not a "delay line" per se, but certainly you can sample an ADSR EG
output and get a series (sort of like an arpeggiator) of time-delayed EGs
out. Yo can also take the 4 outputs to a MOTM-830 mixer, and then shove THAT
back into the input and get no telling sort of stuff out. We may be able to
double that, running up to a 2Khz S&H clocking speed.

e) there is not output lag function like in the '101

f) there is a pot (not an input CV, no room) to set a couple of quantizing
scales. We don't have a lot of room in the ARM's Flash for 256 14-bit scales
:) We can stick 4-6 scales in there. Suggestions for ∗which∗ scales needed.
Note: this module is NOT intended to be a general-purpose quantizer. That is
another module altogether. Rather, this is specifically to quantize the S&H
output. As in the '101, the default S&H input is Pink Noise (no patchcord
inserted into the S&H IN jack).

g) lastly, there is a ∗new∗ feature, enabled by recent high-speed memory
technology. We will be able to ∗record and playback∗ the data into the S&H
"engine". There is enough memory to record 16 ∗seconds∗ at 1Khz clocking.
Note that the ∗input∗ is recorded, not the 4 tap outputs. So, you can record
and X clock rate, and play back at ∗any∗ clock and tap setting! You can also
loop the recorded data. I though this would be a simple "CV recorder" but
again not ∗intended∗ to be something like the Modcan. Rather, something to
'fool around with'.

Thoughts?

Paul S.

 

.