ASM-2?

[Grant Richter]

> 
> Well, I am working on just such a board right now.
> No VCOs or filter since those are best on there own PCBs.
> 
> Current circuit list goes like this:
> 
> Mike Preamp (probably a AD797 with switchable 10-100-1000 gain)
> RIAA stereo preamp (for the DJ in all of us)
> Envelope Follower (both ARP and Buchla styles with gate extractor)
> Analog Noise generator (ala ARP 2600)
> Psuedo Random Sequence Generator (4006)
> Various weighted mixers for above (binary, semitone, whole tone, octave)
> A balanced modulator based on the RC4200 (linearity 0.1%)
> MIDI to DIN synch decoder (using John Blacets PIC, assuming John gives me
> permission) 
> with a divider afterwards to get 1ppq clock for analog sequencers
> Inverter
> Comparator
> Joystick buffer amps
> Sample and Hold (John Talberts design in Electronotes)
> Four input DC coupled mixer
> +10 volt reference
> Voltmeter buffer amp (for the +/- 15 voltmeter)
> Two manual LFOs
> 
> Did I miss anything?

Oh yea, a manual ADSR and a headphone amp.

> This one will be available for DIY purchase through Wiard.
> 
> ----------
> > From: Sean Costello <costello at seanet.com>
> > To: synth-diy at mailhost.bpa.nl
> > Subject: ASM-2?
> > Date: Thursday, July 15, 1999 12:06 PM
> > 
> > Hi all:
> > 
> > I've been bitten by the analog bug again, and have begun soldering in
> earnest
> > (as opposed to programming filters in C for Csound, which has been what
I
> have
> > been working on for the past year or so). I have an ASM-1 PC board, and
> am also
> > working on various other circuits. I am starting to realize just how
nice
> having
> > a PCB to work from is. The diode ladder filter is taking shape, but I
am
> getting
> > sick of running all that bus wire around on the vectorboard...
> > 
> > I have a bit of a dream - a strange little nerd dream, but one that
many
> people
> > on this list could probably relate to. :) It would be nice to have an
> "ASM-2"
> > PCB - a PCB that contains circuts that were not included on the
original
> ASM-1,
> > that would be found in some of the nicer modular systems of the past.
In
> > addition, it would be great if the ASM-2 board could be used by itself,
> as an
> > audio processing system, or maybe as a simple stand-alone synth.
> > 
> > Some of the modules that I think would be useful in the ASM-2:
> > 
> > - Ring Modulator. Could be AD633 design, or a switchable VCA/RM as Ian
> Fritz
> > described in Electronotes (based on an LM13600).
> > 
> > - An additional VCO, similar to the ASM-1/Electronotes VCO, but with
> additional
> > triangle and sine outputs. Used with Ring modulator, or as an
additional
> VCO for
> > an ASM-1 based system.
> > 
> > - Sample & Hold. 
> > 
> > - I guess an added noise generator would be useful to use the sample &
> hold in a
> > stand alone unit. This part of the PCB could be left blank if an ASM-1
is
> part
> > of the system.
> > 
> > - Preamp, for external signals. 
> > 
> > - Envelope follower (preferably with selectable attack and release
> times). The
> > LM3900-based design in the Electronotes PCC looks useful, as it has
> different
> > attack/release times, and can be used as an AR envelope generator if a
> gate is
> > applied. I'm sure that a standard quad op amp could be used in place of
> the
> > LM3900, as the various components of the circuit (preamp, full-wave
> rectifier,
> > buffer for AD capacitor, differentiator) could be constructed using
> standard op
> > amps.
> > 
> > - A voltage controlled slope generator-type thing, similar to the Serge
> module,
> > or the "trapezoid" generator on the VCS3. This would generate AD/AR
> envelopes,
> > as well as act as an LFO, where the AR envelope would cycle. Voltage
> control on
> > the attack and decay times would be included; voltage control of the
> "off" time,
> > as in the VCS3, would be very nice as well. 1 volt per octave control
> over
> > attack and decay times would be useful for using this circuit as an
> additional
> > oscillator. Anyone have any useful schematics? The Serge DSG seems
really
> > cool...
> > 
> > - A 4-pole lowpass filter. The Moog ladder is an obvious choice
(probably
> the
> > best choice), but a 4-OTA/buffer structure might also be nice,
especially
> if it
> > was switchable between lowpass and allpass. A temperature-compensated
> expo
> > generator, with linear FM, would be quite tasty.
> > 
> > - Comparator.
> > 
> > - Pulse divider (for suboctaves and other applications).
> > 
> > - Various utility modules - mixer, inverter, etc.
> > 
> > - Any sort of waveshaping circuits would be nice.
> > 
> > - Frequency shifter (well, this might be better as a circuit board on
its
> own).
> > 
> > I'm sure that there are plenty of other circuits that would be useful,
> but it is
> > a question of how many would fit on a circuit board. All of the modules
> should
> > follow the same standards as the ASM-1 modules, in terms of voltage
> range,
> > temperature compensation, general high quality, etc. 
> > 
> > So, anyone want to do this? ;) As I said, it is just kind of a dream of
> mine - I
> > wish I had the know-how to design something like this myself...
> > 
> > Sean Costello