Midweek Modular: Classic VCOs, Harmonic Safaris and All-Pass filters
3,4 / 5,0 | 
This week, we play with VCOs from The Putney, waveform bending in Local Parks, and ponder the usefulness of All-Pass filters.
Midweek Modular
Somehow, the brains that dwell on modular synthesis have given rise to some more ideas this week. Here are a few of them.
Feedback Modules Putney Oscillators
Designed and built in collaboration with CMS-LABS, Feedback Modules has produced a pair of VCS3-inspired VCOs. They are available in “Standard” and “Premium” versions, which is a very interesting approach.
The snappily named VCZIIIA is based on VCO1 from the classic British synth and has variable sine and sawtooth waveforms. The other one, the VCAIIIB, is based on VCO2 and VCO3, which feature variable triangle and pulse waveforms. They both have the usual FM, Sync and 1v/oct inputs, plus some CV control over the Shape. A Mix Out gives you a blending of the main waveforms, but there are also individual waveform outputs.
The difference between the Standard and Premium versions is in the tuning knob. The Premium has a multi-turnm high precision fine-tuning knob, just like the original synth. A lot of work has gone into preserving the playful character of the original VCOs while introducing better temperature stability and reliable components.
I am really enjoying the green and orange LED rings, which give them a very distinctive look.
Pittsburgh Modular Local Parks
We’re now into Series 7 of Pittsburgh Modular’s strange adventure safari into organically inspired modules. Local Parks is an experimental high harmonic analogue oscillator and comes out of Pittsburgh’s experience of trying to bend waveforms.
The result is a bunch of waveforms that can be pushed and manipulated in all sorts of unexpected directions. It uses Pulse Width and Pulse Shift modulation to produce additional harmonics. The waveform that generates the pulse can also be switched from sine to sawtooth for additional variations.
The intriguing Blade Wave is a morphing sawtooth waveform that’s pitched an octave above the core and somehow shifts back, creating a chorus effect without losing any tuning. Then, we have the binary logic waveshaper, which can combine the pulse and blade into even more interesting tones.
Local Parks is undoubtedly a waveform powerhouse of epic harmonics and is covered in gorgeous flowers – awesome.
Instruo dåpf
The curious dåpf module is a pair of All-Pass filters. The obvious question this throws up is that if it lets everything pass, twice, then what bloody use is it? Ah, well, All-Pass filters are actually about phase relationships rather than frequency attenuation.
So, what you get is two circuits that can provide phase shifting, psychoacoustic stereo enhancement and synthetic doppler effects. You can also use them independently or cascaded for double the phase relationship action.
As ever, Jason’s in-depth video explanation of how he came to design the module is completely fascinating.
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