Re: My ideas for MOAS. (long post!)
1999-02-07 by Dave Bradley
I'm from an Emu modular background, so you'll probably get tired of me suggesting things from that point of view in the coming months. However, Emu DID have an elegant modular sequencer system which we could steal a lot of ideas from, and improve on. BTW, I have a 1978 Emu Technical catalog that is a wonderful resource for info about their entire line. If there is enough interest, I could maybe find some time to scan and post the sequencer pages. For sequencing newcomers, I've included a discussion below on uses of analog sequencing. Forgive me if I'm preaching to the choir<g>! Someone mentioned the Emu 4060 keyboard sequencer in a discussion about "why analog sequencing?" I own one now (which is shortly going to Dave Kean's Emu synth museum), and also worked with a maxed out 4060 w/ disk drive in a very large electronic music studio years ago. You used these types of "recording" devices like you would a MIDI sequencer today - basically play stuff in real time and build up complexity in multiple recording passes. This was a system capable of 16 tracks back when synthesizers had barely gone polyphonic! Because each track was output to a separate signal chain, you had intimate control over the sound of each channel. Sounds like a modern multitimbral synth, right? I remember sequencing some Aaron Copeland stuff in the late 70's on analogs that would fool you into thinking it was an orchestra. The ability to edit notes on this system was present in a primitive fashion in a special software version commissioned by Patrick Gleeson (prominent 70's synthesist), but was nowhere near the level of even the most rudimentary software MIDI sequencer today. The 4060 type of sequencer is IMHO obsolete today. However, the analog step sequencer is a different kind of beast. Yes, you can use it for manually generating short phrases, but it's not the tool you would choose to do things that were better played in from a keyboard. Think of it as a pattern generator, which can control pitch, yes, but also anything else. A flexible system will have inputs and state outputs to allow it to be self modifying in interesting ways, probablistic and otherwise. Clock it at high speed and you have wavetable synthesis. Set up 3 filters under sequence control, slap some lag on the step outputs, and you have moving formants. Etc etc... Back to MOAS, here for reference is how the Emu modular system was broken out. I'm doing this from memory, so I may make a mistake or two: 1. Voltage Controlled Clock module. Flexible, includes PWM, and can be gated to 2 different outputs. Has an inhibit input. 2. 8 Stage Address generator module. No pots. This is the counter / shift register piece. Clock Up, Clock Down inputs. Each stage has a gate output, a Set input that forces that stage active (very important IMO), a lamp indicating when the stage is active, and a manual Set pushbutton, again to force that stage active. You can force any stage to follow another by patching its Set input from the gate out of the other. Multiple address generators can be chained together by using a Carry output and a Borrow input (note the counter terminology). The current state is output in binary form on 3 jacks (binary 1-8 == 000-111). Interestingly, it has no random stage select capability like we see in other designs. 3. 8x4 Pot Matrix module. Has 3 jack binary input to connect to address generator. 1 output per row, and an inhibit input forces all voltage outputs to zero. 4. Misc logic modules - OR gates, inverters, etc. Quad analog switch module, can be used to convert 8x4 voltage matrix to 32x1. 5. Digital memory module. 256 locations (I think), each can record a voltage and a few gate signals. Has a clock input and a record enable input. 6. Digital address programmer. Connected to one or more digital memory modules, has an octal address display (awkward by today's standards). You set the address you want to program, enable record on the memory module you want, input the voltages and gates to the programmer, and blast it in. Well, I've blathered long enough - I'll leave the connection possibilities to your imagination. Dave Bradley Principal Software Engineer Engineering Animation, Inc. daveb@...
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> >Paul Schreiber wrote: > >> Here is a brief outline of the direction I am going: > >> > >> 1) It's modular > >> 2) Has full MIDI control, but all outputs are analog > >> 3) Patch memory > >> 4) I can be BIG. I mean *REALLY BIG* - 256 stages x 64 rows > >> 5) The modules are tied to a local LAN than reconfigures the > modules, ie > >> Plug-&-Play. > >> 6) This being MOTM and all, no cheesy pots. We're talking > optical encoders, > >> baby! > >> 7) uP will be in C programming, with "open source code" posted on the > >> website.