The limitations of a basic learning device should not frighten those who are
seriously curious about entering an unknown territory. Someone previously
mentioned the "why" of our usual synth functions, and this is important to
keep in mind. Maybe you might find it interesting and rewarding to patch a
poor response VCF up from the ground? Remember, many musicians would
consider using your Serge instead of MIDI synths tedious and plain useless.
All options available today, besides Comdyna only Lab Electronics
http://www.surfindia.com/labelectronics/homepage.htm, are primarily intended
for educational purposes, which is what most of us here probably have to
start with when aiming at new musical paradiems through the use of analog
computers.
For a very nice example of what can be done with large analog computing
systems search the SDIY archive http://www.buchi.de/sdiy for ' bouncing
ball' ;->
Kind regards,
Sebastian Kuehnl
seriously curious about entering an unknown territory. Someone previously
mentioned the "why" of our usual synth functions, and this is important to
keep in mind. Maybe you might find it interesting and rewarding to patch a
poor response VCF up from the ground? Remember, many musicians would
consider using your Serge instead of MIDI synths tedious and plain useless.
All options available today, besides Comdyna only Lab Electronics
http://www.surfindia.com/labelectronics/homepage.htm, are primarily intended
for educational purposes, which is what most of us here probably have to
start with when aiming at new musical paradiems through the use of analog
computers.
For a very nice example of what can be done with large analog computing
systems search the SDIY archive http://www.buchi.de/sdiy for ' bouncing
ball' ;->
Kind regards,
Sebastian Kuehnl
----- Original Message -----
From: <r_a_quirk@...>
To: <SergeModular@yahoogroups.com>
Sent: Sunday, May 06, 2001 1:30 PM
Subject: [SergeModular] Comdyna info from Mr. Slater
: Hi,
:
: Dan's email is pretty complete, and just about answers
: all of our questions. Enjoy!
:
: >From: Dan Slater <dslater@...>
: >Reply-To: dslater@...
: >To: Richard Quirk <r_quirk@...>
: >Subject: Re: Comdyna GP-10S
: >Date: Sat, 05 May 2001 22:27:38 -0700
: >
: >Hi Richard;
: >
: >Sorry for the delay in replying. I had a very busy
: week
: >
: >Richard Quirk wrote:
: >
: > > Hello again,
: > >
: > > I posted a message to a Serge newsgroup on Yahoo
: asking if anyone had used or owned any Comdyna
: analogue computers. There was quite a bit of interest
: so I directed them towards your website and told them
: what I'd been told in letters from Ray at Comdyna.
: > >
: I have been asked to ask you if you wouldn't mind
: explaining what the GP-10S can do (i.e. will it do the
: functions as described in the analogue computers page
: on your website), and how it can be used for musical
: purposes - & I will post this to the newsgroup (or you
: can join it yourself [SergeModular@yahoogroups.com]).
: The people on the website, like myself, don't have any
: great knowledge of maths, but there are quite a few
: that are very interested in buying a GP-10S if it can
: lead to new musical horizons without too much
: difficulty. Hopefully this makes sense.
: >
: Although I talked with Ray a number of times about the
: GP10s I don't know its exact final configuration and
: specifications. I believe that it is a scaled down
: version of the GP10 with 2 rather than 4 integration
: ranges (ie., 2 vs 4 capacitors) for each integrator
: and it uses somewhat less expensive integration
: capacitors. I believe that the GP10s has 8 coefficient
: potentiometers (attenuators), 4 initial condition
: potentiometers, 4 integrators, 4 summers and 8 trunk
: lines. Two multipliers can be added as an extra cost
: option.
: >
: Analog computers were originally designed to solve
: differential equations. Virtually all analog computers
: include 3 basic functions, integrators, summers
: and coefficient potentiometers.
: >
: Integrator -- The integrator forms a time integral of
: a voltage. It is implemented using capacitor feedback
: with an operational amplifier. The integrator stages
: can alternately be used as simple summing stages.
: >
: An electronic switch within the integrator allows the
: integrator to be electronically switched between a run
: state, hold state and reset state. When set to the run
: state, the integrator integrates the input signal. The
: hold state freezes the signal, similar to a sample and
: hold. The reset mode switches the integrator into an
: initial condition set mode. Associated with each
: integrator is an initial condition set potentiometer.
: This used to set the integrator output voltage prior
: to the start of an integration. Comdyna uses a sort of
: strange set of negative voltage levels to control the
: integrator mode. If you want to use the run/hold/reset
: capability with the GP10s you will have to produce the
: mode control signal externally. A second control
: signal can be used to select between the two
: capacitors. This signal also would have to be provided
: externally.
: >
: Summer -- A summing amplifier adds together several
: voltages and changes the sign. The summing amplifier
: is implemented as an inverting operational amplifier
: circuit with multiple inputs and resistive feedback.
: The GP10s has 4 of these with varying numbers of
: inputs.
: >
: Coefficient potentiometer -- Coefficient
: potentiometers multiply a voltage by a fixed value
: between 0 and 1. They are just a potentiometer setup
: as a voltage divider. For scientific applications,
: coefficient potentiometers need to be set precisely.
: Most analog computers include a switching network so
: that the potentiometer multiplication factor (with
: circuit loading) can be measured directly on a digital
: volt meter (DVM). I think that the GP10s internally
: has
: this switching capability although an external meter
: and control switch would be needed.
: >
: Trunk lines -- There are 8 lines that go to the rear
: panel as a convenience. You can use these as a
: convenient way of bringing inputs and outputs to the
: unit. They are just wires with no active components.
: >
: Multiplier -- The GP10s can accept 2 multipliers. I
: don't believe that these are included in the basic
: unit, they would need to be ordered as an extra cost
: option. The multiplier requires the use of either an
: integrator or summing amplifier as it provides a
: current output. It can be put in the feedback path
: and then function as a divider.
: >
: The GP10s can be patched to do a variety of basic
: functions including adding (mixing), scaling,
: subtracting, multiplying (VCA / ring modulation),
: switching, simple oscillating, simple filtering, etc.
: But a modular analog synthesizer would generally do a
: much better job here. A VC state variable filter for
: example would pretty much use up all the resources of
: the GP10s and not work nearly as well as an analog
: modular version. For example it would have a linear,
: not exponential frequency control and it would have a
: smaller VC tuning range. The GP-10s is a very small
: analog computer that is primarily useful at the
: introductory level but would rapidly run out of
: capability for more than the most basic patches just
: as a tiny music synthesizer would also have
: significant
: limitations.
: >
: In general, an analog computer is not a substitute for
: an analog modular synthesizer, but a tool for
: exploring new concepts. The strength of the analog
: computer is in the solution of linear and non-linear
: differential equations. This world tends to be foreign
: to the musician, just as midi, frequency shifters
: and arpeggios would be foreign to the mathematician.
: There are countless capabilities of the analog
: computer but they are not as VCO, VCA, etc. They are
: as a virtually infinite set of mathematical models.
: >
: Chaotic systems is an example of an area that works
: well with analog computers. Chaotic systems can also
: be created directly in analog modular synthesizers.
: The
: article on my website provides examples of both analog
: computer and analog synthesizer chaos in a musical
: context.
: >
: Polynomials can be generated by cascading integrators,
: this can provide an interesting type of envelope
: function, although it is a bit difficult to control
: in real time. These can further be enhanced by mode
: switching the integrators. Analog computers excel in
: the simulation of dynamic systems. These can provide
: interesting musical models, both as sound and CV
: generators, although the limited computing capability
: of the GP10s would limit the exploration of this
: area considerably. There are many other interesting
: mathematical systems but they also are generally
: beyond the capability of the GP10s.
: >
: >Best regards;
: >
: >Dan Slater
:
:
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