Analogue Solutions - Polymath
Polymath is a 4 voice paraphonic analogue modular synthesizer, with built in analogue step sequencer, arpeggiator and spring reverb.
The circuit designed is quite literally from the 1970s. It has a very old sound. And isull of character. Analogue synths of the 1970s had that just ever so slightly drifty sound that many would agree is so much more full of life than many of its digitally sanitized analogue synths.
Let’s deal with the two main labels in isolation, paraphonic and modular.
Paraphonic is half way between a traditional monophonic and full polyphonic synth (though closer to the second).
Up to four note chords can be played, since it has four separate oscillators. However, it only has one filter and one amplifier section. Polyphonic synths usually have a filter/vca/envelope per voice/oscillator.
Traditionally this kind of polyphony was used to save money, since instead of four filters, four envelopes and four amplifiers (for a four note polyphonic synth), you only need one set share between the four VCOs. It would also save space as a much smaller PCB can be used and ultimately the reason was also to save cost.
However, this isn’t really the full reason we have chosen this implementation.
It is true money has been saved, but this saving has been used instead to invest in other extra features like the analogue sequencer and spring reverb.
The main reason is we chose paraphonic is we wanted this synth to be mostly modular. A fully patchable polyphonic modular synth is an absolute nightmare and a sea of patch cables. We know, because we have tried this! The patching is significantly reduced using the paraphonic method.
With paraphonic, you get the best of all worlds but still remaining practical. With a small number of patch leads you can set up a simple paraphonic patch and still be able to see the controls through the cables.
Also paraphonic implementation offers its own creative advantages over monophonic or polyphonic systems in the way voices can be cross-patched to cross-modulate. A paraphonic synth also has a different ‘sound’ to a full polyphonic synth, and being different is always good!
There are several terms like modular and semi-modular that are bandied about in the synth world. There is no standard in their meaning, and often they are used incorrectly (you only have to look at descriptions of old and new synths on forums, manufacturer web sites and places such as ebay). People have different opnions about how patchable a synth must be before it can be called modular.
There are many synths now that have a handful of sockets and get called modular. The term seems to be applied to synths that have ‘fixed’ circuits and those where sections can be swapped out. Some people think modular means that the circuits like VCOs must be able to be physically removed, swapped or changed with other circuits, like say, VCF. (For instance a Concussor or Doepfer modular) to be classed as modular.
Some say the synth can be called modular if the circuits are fixed and not swappable, but has a full complement of sockets.
I won’t debate which is the correct description of semi-modular or fully modular, but I would say Polymath can safely be classed as modular!
What we can say is that every circuit is completely independent, and can be patched where you want with just a few exceptions. The exceptions are there to reduce the amount of cable patching to a reasonable level. Where there is prepatching within Polymath, it can almost always be ‘cancelled’ by zeroing a control or flicking a switch.
The control voltages from the MIDI-CV converter are prepatched to each VCO, VCF, VCA, EGs. However, in many cases the signal can be switch out via a toggle switch. In a similar way to above, some other signals are pre-patched to other circuits, but once again can be ‘turned off’ via a control or toggle switch.
The position of many key sockets has been carefully chosen so that in the most common patches the patch cables can be short, and will not ‘hang’ over the controls and obscure front panel vision. E.g., the VCF audio output socket is right next to the VCA audio input sockets. Since you’d normally patch these together we placed the sockets right by each other.
• 4 VCOs. Each have Pulse Width, Portamento, Saw wave, Square Wave, CV inputs, CV outputs, Sync. VCO1 has Sub-Osc output too.
• Multimode VCF based on (not a clone) the Oberheim SEM (LPF, BPF, HPF, Notch) with multiple CV control
• Audio input, to allow processing of external audio (vocals, for example, from your DAW, etc) through the filter
• 2 LFOs
• 2 ADSR Envelopes
• 8 Step Analogue Sequencer with sliders
• Arpeggiator – with Up, Down, Up/Down modes and Octave range
• Poly Mode (Paraphonic)
• Note Trig/ReTrig
• Unison Mode for mega-fatness
• Ring Modulation
• Sample and Hold
• Spring Reverb – a triple spring Accutronics unit is used.
• MIDI to CV Converter
• Headphone Amp
• Hand built in Great Britain.
• Real Wood sides made by Lamond Design
• Solid steel and aluminium construction
• Carry handle
• Includes an assortment of patch cables