Vermona QuadroPOL
The quadroPOL is a neat little utility module from Vermona with a surprisingly long list of uses — always a good thing in modular systems, particularly when space is at a premium. Each of its four channels has a single input for audio or control signals, plus CV control of the level, a bipolar level knob and finally a discrete output. Depending on the settings of jumpers on the circuit board, you can optionally cascade the output of any channel (or all) down to the next. The action of connecting a cable to an output cuts the downward feed.
Already, its functionality covers that of a voltage-controlled four into one mixer — or other configurations as required. The bipolar control doesn’t produce an audible effect on audio, but when you’re blending control signals — eg. several LFOs or envelopes — it’s particularly cool to be able to invert one or more of them. The level control has a central dead zone to ensure you can easily disable attenuation.
Perhaps an even more important role for many systems would be as a compact quad VCA, where typically you’d plumb in envelopes to drive the signal level. Again, the control’s bipolar nature means you can smoothly morph between a regular and inverted envelope, but the same applies to any modulation source. All inputs operate between -5 and +5 V and since LFOs typically oscillate between positive and negative voltages, the result will be a change of phase at the output, unless you apply an offset (or use a unipolar LFO). You can, of course, combine functionality, such as using one channel as a VCA while the others are a 3-1 mixer. As a VCA, the quadroPOL is clean and responsive, with a dynamic range of 80dB and no discernible crosstalk.
Other uses become apparent as you start to experiment and one of the simplest is as a series of attenuverters for audio signals or control voltages. And when no input is connected, the module generates four static DC signals at the outputs, in the range -5 to +5 V. One use of this might be to supply the offset for another channel, turning a bipolar into a unipolar source. Finally, to round things off, if you connect two audio signals (one to the CV input and the other to the regular input) the quadroPOL will produce the sum and difference of their frequencies, in effect acting as a ring modulator. Here the level control serves to balance between the input signals, therefore changing the ring mod’s flavour. There’s nothing to stop you applying this process to a pair of LFOs too, and creating complexity from otherwise plain modulation sources.
The quadroPOL is one of those modules you could easily use in every patch. It meets Vermona’s usual high construction standards, being chunky and fairly accessible, given that jacks are positioned on either side of the central knob column. It works admirably as a VC mixer or quad VCA, with the ring modulation and the polarising qualities adding something extra to sweeten the deal.
