To: "'Vampeiyre@aol.com'", Vampeiyre@aol.com,
From: "Caloroso, Michael E" CalorosoME@corning.com,
cc: "'\[*AH\]'" analogue@hyperreal.org,
Subject: [AH] Polymoog Architecture/Parameters
Date: Mon, 10 Apr 2000 12:38:41 -0400
> Well, exactly what kind of architecture is on it? What parameters can you actually alter?
>
It's a fully polyphonic two-oscillator TOS system like an organ, but you have ADSR control and limited filtering over *every* key. Each key has a custom Polycom IC that contains a waveshaper, two VCAs, an EG, and a limited two-pole (12dB/oct) ladder VCF with no resonance. The Polycom's EG affect the VCA and VCF together. Due to lack of resonance control, the Polycom's VCF is best described as a treble control and misses out on a lot of potential.
Then all the signals go to preset filters, to a resonator, and to a Moog transistor ladder filter (parallel, not series). *But* there's only a master of each for the whole system, as opposed to a VCF per voice on the Prophet 5 and other proper polyphonics.
There's no way to do cross modulation; everything you can do with the Prophet 5 polymod section, you can't do on the Polymoog. That limits its palette.
The Polymoog have an LFO for each oscillator, for PWM and for VCF; four LFOs sounds like a lot but they're all triangle and it doesn't do enough to the sound.
***************
Parameters
***************
There's a real good pic of the front panel here http://www.synthfool.com/images/polymoog2.jpge http://www.synthfool.com/images/polymoog2.jpg
The front panel parameters do not apply to the preset-only Polymoog Keyboard.
The keyboard is velocity sensitive and has a fixed split point at two octaves from low E. Parameters indicated by lower/upper refer to separate control over each split. It's kind of a disappointing split system.
The velocity control works good, but when you hold the sustain pedal down and press the same key repeatedly the sound gets increasingly louder, even if you press the key softly. That's a fault of the charged cap system used for velocity sensing and there's no way to fix it.
One nice feature is that the Polymoog has CV with glide and trigger outputs for controlling an external monosynth, and you can route the external synth audio to the AUX mixer slider. You can split the keyboard for CV control. Alas, when using the entire keyboard the CV only works on the top half so there's no way to get all 71 notes as a monosynth controller. It also has a trigger input, but it only affects the VCF envelope generator.
There are eight presets and a VARiable mode. In VARiable mode the entire panel is live, but you can't store sounds. The presets are Strings, Piano, Organ, Harpsichord, Funk, Clavinet, Vibes, and Brass. Selecting a preset programs the sound with resistors/logic circuits and a preset mode filter is selected. Strings and piano are the most useful. Brass, Harpsichord, and Vibes are OK, Clavinet is passible, Organ doesn't sound at all Hammondish or like any organ I've played, and I have yet to find a use for Funk.
The idea is to use presets for "starting points" for other sounds, IE you select Strings and then start setting the panel to make other sounds like pads. Each "block" of the front panel has a set of "VAR/PRE" buttons; "PRE" is the internal preprogrammed setting (the sliders are not active), and "VAR" makes the sliders in that section live.
There's also a button with a "." on it marked "PART/FULL". This one's kind of strange. You use it to lock live panel settings when you go from preset to preset.
If this sounds convoluted, remember that the Polymoog predated the Prophet 5 by three years.
When you look at the mixer section on the lar left, "AUX" is the external signal, and "DIRECT" is the Polymoog direct signal before mode filters, resonator, and VCF. The "MODE" mixer slider brings in the audio from the preset filters.
The VCF is also preprogrammed when you select a preset and the "VCF" mixer slider brings in the audio from the VCF.
The resonator is not preprogrammed at all. It's a three-band parametric EQ with low-pass, band-pass, and high-pass mode, and it's quite effective. The "RES" mixer slider brings in the audio from the resonator.
All outputs are available simultaneously. Most of the time I use MODE and VCF together.
You can route external signals to the resonator and to the VCF, and you can cut off the Polymoog signals so that these work on only the external signal. The rear panel has separate inputs for each. This is separate from the AUX input that is affected by the mixer slider.
The Polymoog actually has three independent keyboard splits; The Octave balance sliders controls the balance between the three sections, sort of like low, middle, and high balance controls. Otherwise the Polymoog is only splittable two ways, the middle and high are combined.
Confused yet?
Pulse Rank Oscillator:
-----------------------
waveform select (lower/upper)
octave (8' or 16')
FM amount/frequency
pulse width (lower/upper)
PWM (lower/upper)
PWM LFO frequency
Ramp Rank Oscillator:
-----------------------
waveform select (lower/upper)
octave (8' or 4')
FM amount/frequency
volume level (lower/upper)
detune
lock*
*You can lock both oscillators together; but it's phase lock, not hard sync. You can't get the traditional sweep sync sounds; it's impossible with the TOS system of the Polymoog. Moog really missed the ball on this one. When the oscillators are locked there's a phase shifter available (FM doubles as PM) but it's very bland, you almost don't hear it.
Loudness Contour
-----------------------
Keyboard Dynamics
Attack
Decay/Release (lower/upper)
Sustain
Final Decay On/Off (aka Release)
Again, only decay/release is independent of each split. Big disappointment. One other major fault is that if you raise the attack higher than the decay, the sound disappears; that's the fault of the Polycom IC. So you can't use an envelope with shorter decay than the attack. Very limiting.
Resonator
-----------------------
High/Low/Bandpass mode
Three independent parametric EQs, each with cutoff frequency, emphasis, and gain. You can route all, either half, or none of the Polymoog through it.
Surprisingly this is the most effective tool in the Polymoog. Many owners use it for processing external signals.
Voltage Controlled Filter
---------------------------
Cutoff Frequency
Emphasis
Keyboard Tracking
LFO rate
Amount
S&H amount
Attack
Decay Release
EG amount
One master VCF for the whole thing, and it's a crippled VCF in that it doesn't self-oscillate. Why? The VCF is last in the sound chain, there's no post-VCA to cut off the ringing; the VCAs are pre-filter, in the Polycom IC. You could reset the calibration trimmer inside so that it will self-resonate, though. This is the same reason that it doesn't have a noise source.
You can route all, either half, or none of the Polymoog through it.
The VCF doesn't sound Moogish to my ears.
The Polymoog is best at strings, block chords, and pads, and not much else. It sounds unique, looks great, and in its day every keyboard player dreamed of owning one. But everyone wanted a polyphonic Minimoog and it didn't (and won't) sound like one. When the CS80, OB Four-voice, and Prophet-5 became available it quickly fell from favor. I think the design of the front panel is very ergonomic, you can get to anything quickly while you're playing the Polymoog. It's the best functionality to space ratio I've worked with.
The Polymoog was a long LONG time coming in R&D and was never "finished". There were over 200 engineering changes to get it in production and it had a high failure rate. David Luce kept changing the design and just couldn't be satisfied to put down the pen and say "it's done". Luce isn't entirely to blame, Moog Music had a *lot* of input from musicians in the beta phase, maybe too many.
The card connectors for the Polycom ICs are not reliable and the abundance of connectors in the thing added to the failure rate. The connector contacts are tin plated and are forever oxidizing, they have to be cleaned periodically. Most polymoog failures are mechanical, the ICs are pretty robust. The sliders are very good quality also, something you can't say about ARPs of the same age.
MC
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