K P T synthesis
is a modular synth on the go
Small modular synth aimed towards drones, noise, and experimental sound. It is powered by USB, so any 5 volt USB power source will turn the unit on. Almost every parameter has voltage control via the banana jacks. The green jacks are inputs for a signal to be processed, the black ones are voltage control inputs and the red jacks are the outputs. It can be used to process external sources, or used as a sound source by itself. The unit contains 2 oscillators, 2 lowpass filters and 2 VCA's. Beside those modules there's a couple of interfacing modules, to connect the synth to the outside world. This type of banana jacks were chosen because you can not only patch them with cables, but they can also be touched, and control the synth that way! A closer look at the modules available:
USB power and external input
The power is drawn from the USB port. A tiny LED just above the upper knob indicates that the synth is on. The 2 mini-jack connectors are external inputs. They have attenuators for lowering the input amplitude and have overvoltage protection after the attenuators. The inputs are DC coupled, so you can connect external control voltages here (or your laptop, or any other audio source, as long as it's loud enough).
The VCO's have 2 voltage control inputs for adjusting the frequency, and 2 inputs for adjusting pulse width. It has 2 outputs which give a saw wave and a pulse width modulated output, whose width is dependant on the setting of the PWM knob and the voltage at the PWM inputs. Frequency voltage control input is linear-ish, but don't expect a nicely scaled VCO here!
The filter is a 12db/octave resonant lowpass filter, which can really mess up your signal. It has voltage control over the resonance and cutoff frequency. It's all based on nice and fast vactrols, but they're still vactrols, so the reaction of the filter can be sluggish.
2 vactrol based VCA's in one module, both have 1 input, 2 voltage control inputs and one output. Input is attenuated according to the knob setting and the voltage at the control inputs.
Dual attenuator and output
The 2 attenuators can be used to lower the amplitude of any signal. They both have 1 input and 1 output. The jack output has corresponding inputs to the tip and the ring of the jack. The left input is the tip, the right is the ring. The output is AC coupled, so you can safely connect headphones here. Please, do use an attenuator if you use it with headphones, because the output can be loud!
5 v USB
2x filters HP / LP / res
fat analog sound
inc 12 banana plugs
come and test the errorlab
made by Daan J