Mystic Circuits 0HP Modular – PCB+Baseplate

£1.80 (Excl. VAT)

0HP is a line of passive external modules by Mystic Circuits

This page is for PCB and acrylic baseplate packs only – these are not full kits.

These are not Eurorack Modules but fully Eurorack compatible standalones! Zero hp!

£1.80 (Excl. VAT)

In stock

SKU: Group_Mystic_0HP-PCBs Categories: , , , , , , Brand:


These products contain ONE PCB and ONE Baseplate.

0HP is a new line of passive external modules by Mystic Circuits. Whether you need some extra utilities for your studio behemoth or you need to save space on the road, 0HP gives you extra options outside of your case. Modules are designed as a small circuit board mounted to a colourful piece of laser cut plexiglass, with a small chance to get one of our fabulous rare colours. More 0HP videos can be found here: Mystic Circuits on Youtube


0HP – Filter

An audio filter in a tiny package! A blend between the “AND – gate” and “Vactrol Low Pass Gate” circuits, the cutoff frequency can be modulated at audio rate. It also features a voltage controlled clipping circuit which allows for further wave shaping.  The response of this circuit is much faster than that of the Vactrol Low Pass Gate, so it will react to very plucky envelopes and even triggers.

Filter: Video Build Tutorial

0HP – Eyetenuator

Control your synth with the power of light!  Two signals coming through this 0HP module are attenuated based on the amount of light hitting their respective photo detector.  Normalized jacks allow one input to be sent to each attenuator or for both attenuators to be summed together at one output.

Eyetenuator: User ManualVideo Build Tutorial

0HP – Vactrol Low Pass Gate / VCA

Both of the Vactrol based modules use the same PCB design but involve slightly different components. 0HP Vactrol based modules take advantage of an outdated part to rough the edges of your sound. What sets Vactrol-based circuits apart is that they will slow down any incoming control voltages, allowing them to convert a gate or trigger CV input into very musical envelopes. Both the Vactrol Low Pass Gate and the Vactrol VCA modulate the amplitude of a signal under voltage control, but the VCA does so with minimal alteration to the sound whereas the LPG filters the sound to give it some extra weight. Both modules feature a ‘mix input’ allowing for passive mixing with other sound sources or daisy chaining of multiple Vactrol modules. Please note that all Vactrols are unique snowflakes and as such each module will have a slightly different response curve.

Vactrol LPG / VCA: User ManualAssembly GuideVideo Build Tutorial

0HP – AND Gate & VCA

The 0HP VCA/ AND gate acts like a faucet: When a high control voltage is present, the input is allowed to flow to the output. When there is a low control voltage, the flow is restricted and nothing is present at the output. Using a high speed optocoupler, the module accepts audio at all inputs so audio-rate amplitude modulation is possible for pseudo-ring modulation effects. When used with gates at both the input and the CV input, the module acts as a logical AND gate (an AND gate outputs a high voltage when both of the inputs are high.) A built in trigger converter outputs spike whenever the main output transitions from low to high.

And Gate: User ManualAssembly GuideVideo Build Tutorial

0HP – OR Gate

The 0HP OR Gate can be used to combine different signals, usually gate or clock signals.  The output will give a high voltage whenever a high voltage is present at either of the inputs.  This can be useful for combining multiple different gate sources together to trigger the same module, such as using a gate sequencer and a burst generator on a drum module to get drum fills.  This module can also process fluctuating voltages, outputting the maximum of the two inputs (the highest of the input voltages above 0).  The built in trigger converter outputs a spike whenever the main output transitions from low to high.

Or Gate:  User Manual – Assembly Guide – Video Build Tutorial


Since the modules are passive, some signal loss and distortion should be expected. The user is expected to keep cables away from the top of the circuit board. While in 99.9% of cases an accidental short circuit is not an issue, Mystic Circuits, Eli Pechman and Thonk assume NO RESPONSIBILITY for modules that are accidentally damaged by doing so. This expectation follows the same logic as not plugging an output into another output or touching your cables to the panels, which are common safety practices expected to be followed by the end user.

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