Monday, February 04, 2008

New module developments

Last week, Paul Schreiber reported the below on the MOTM users group, feedback is encouraged:

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'.


Paul S.


To me this seems like a great new development, and indicates yet again that the future of MOTM is largely based on digital and SMT technologies, because there are already plenty analog designs out there, and in the MOTM product list. The combination of these analog modules, with the new digital ones is opening up new sonic capabilities and horizons :-)



Post a Comment

<< Home