Friday, September 14, 2007

More about MOTM system of the week



Hello all,

Here is more info on the MOTM modular featured in an earlier post on my blog.

Dave gives us the following info on his synth.

On the lower left bottom a home brew 1u panel that I had used with some stereo equipment to get access to the ins and outs without going around and unplugging stuff. The top jacks are normalled to the bottom jacks and a pair of RCA jacks in the back to go to the equipment. Inserting a plug breaks the normal and connects the plug to the corresponding jack in the back. I am using it to fill the space and connect the synth to the Heathkit AA-15 amp on top of the synth.

Next up is a shelf of synthesizersdot com modules. From left to right:Q118 Instrument Interface Module, Q125 Signal Processor, Q123 Standards Module, Q106 Oscillator, Q113 Mixer, and a Q108 Amplifier. By the way, the whole thing is powered by a QPS1 power supply.

Above the dotcom modules is a multiple panel based on the MOTM cascaded multiple. The top and bottom rows are identical.. There are 20 jacks connected in series, with very 4th jack interrupting and isolating the jacks preceding it, like the MOTM 940, only longer. I set them apart at the same interval as the MOTM form factor and had 2 FPE 1u panels made. I do need to reinforce them, however. There is an identical multiple on the right side.

The top shelf is (left to right): MOTM 800 EG, MOTM 320 LFO, MOTM 300 VCO, MOTM 310 uVCO, MOTM 300 VCO, and another MOTM 310 uVCO. The blank space is reserved for the MOTM 890 uMixer when I get it.

In the right side bottom is a Middle Atlantic Products Inc rack mount power strip. It supplies AC power to the QPS1, The BK 1472 Oscilloscope, the Heathkit AA-15 amp, the BK Function Generator, and the PAIA 9700 Midi to CV Converter.

The nest shelf is the "control" shelf. The first module is a MOTM 101 Noise/Sample and Hold. Then a blank space, then a MOTM 820 VC Lag Processor, a MOTM 800 EG, and the PAIA MIDI to CV Converter. I put the 9700 in a Blacet to MOTM panel adapter.

The right side top shelf consists of a MOTM 420 VCF, A MOTM 800 EG, another MOTM 420 VCF. In the blank space I would like to put a 24db/oct Low Pass Filter based on the CEM 3320 chip. Next is a MOTM 800 EG, and 2 MOTM 190 uVCAs.

Hope this answers any questions anyone has. I not musically inclined ( my wife and daughter are). I became interested in electronic music after listening to Switched on Bach in 1969. Other things took priority over the next 30 years (military service, raising a family, etc). In 1998 I discovered the Internet and found a wealth of information on building synths. I always wanted an Aries 300 but could never afford it. When I found the Synthesis Technologies site I decided it was the way to go. thanks, Dave Abbey.


T J

2 Comments:

Blogger synthetic said...

Cool design with the rows of multiples. I would still like to hear your thoughts comparing the MOTM and Dotcom oscillators. Is it worth mixing the two, or would you have all-MOTM if price were no object?

12:11 AM  
Blogger David said...

The Dotcom oscillators are good, exhibit a tiny bit more distortion than the MOTM oscillator, and I think they are easier to tune. The MOTM oscillator is better engineered and built. It seems to be rock stable but I haven't done any long term experiments to see if the dotcom oscillator drifts more. The MOTM oscillator has higher quality Spectrol and Bourns pots in them that rotate more freely than the Alpha pots in the dotcom oscillator so I get more "backlash" when I let go of the knob. Solution? More patience! The Dotcom oscillator does have an inverted sawtooth output called a ramp that is useful for modulating other modules. I really like the 300 and the 310, as well as the 320. I do use my MOTM oscillators more than the Dotcom and probably would not have considered it if I hadn't bought a shelf thinking I would go that way. It is good oscillator, though and I think it boils down to Moog or MOTM form facor preference.

5:59 AM  

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