Bastl Instruments - Tromsø


Tromso contains three separately useable circuits: a voltage controlled triangle wave oscillator, a comparator and finally a sample & hold which can be used as a track & hold alternatively.
So far it is a handy small tool but normalizations between the individual sections make it even more interesting because in this case the module is great for analog downsampling of audio signals i.e. as a sample rate reducer.



Once there was an entirely analog downsampler box from Norway called Distortotron, made to imitate and exaggerate the artefacts of old samplers. The Tromsø module is a tribute to this machine which was responsible for the specific sound of some artists from Norwegian town of Tromsø.

VCO: Simple oscillator which generates a triangle wave. It has one CV input which tracks 1V/oct when the attenuator is fully open. A switch alternates between two ranges: LFO (50s - 50Hz) and VCO (15Hz - 45kHz).

Comparator: A signal at the input is compared with the voltage which is either set with the Threshold potentiometer or by a CV plugged into the threshold input. If the input is higher than the threshold then the gate at the comparator's output will go high. If the signal drops blow the threshold, the gate will go low again.
The VCO's triangle output is prepatched to the comparator input so the output is a square wave with the pitch of the VCO. By changing the threshold you can set the pulse width.

The sample & hold has an input for the sample signal, a gate input which determines the moment of sampling and finally an output. The comparator's gate output is pre-patched to the S&H's gate input.
This section has a second mode, track & hold, which will output nothing when the gate is low and will pass the input when the gate is high.

For downsampling effects just keep the normalizations and patch the signal which you would like to process to the S&H's sample input. Play with the Threshold potentiometers and use the T&H mode as well to vary the effect.


VCO: exponential FM input, triangle output
comparator: Threshold input, signal input, output
S&H: input, gate input, output


3U Eurorack module, 5HP wide, 45mm deep
maximum current draw: 35mA at +12V and 35mA at -12V

0.1 kg
Article Number
former retail price: €109.24

This item is discontinued or sold out and no longer available, please feel free to look for comparable new stuff in the following categories.


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