0HP Eurorack Modules from Mystic Circuits

Mystic Circuits is known for some far out module design, like their extremely fun gate sequencer, Vert. Now Eli and the Mystic Circuits team have developed a new floating module system in the tradition of external mults, called 0HP. These innovative, business card sized modules dangle from or rest on your eurorack system, performing basic but crucial functions.

0HP “modules” are ingenious. Simple passive circuits (requiring no additional power source) rest at the heart of these open source devices. Available assembled or in DIY kit form, the 0HP line provide important tools that any modular user might need.

We all need more VCAs. Perhaps the most useful device in the line is the VCA/AND Gate, a passive VCA with an additional trigger output. When a signal is patched to the input, AND the CV input recieves a high voltage, the signal is sent to the output. With a gate, we get the AND logic functionality. When an envelope is used instead, we can shape the amplitude of the input signal over time. The circuit might be passive, but it can handle audio rate modulation, applying amplitude modulation to the incoming signal for some deep tonal manipulation.

The OR gate is another handy device, combining two CV or gate signals to a single output. This circuit can be used as a simple mixer with no attenuation, making it useful for many purposes. The module works well as a gate sequence mixer as well, allowing the signals from both input 1 OR input 2 to pass to the output, a fun tool for combining a steady a pattern with a more complex one for fills or embellishments.

Mystic Circuits has just released two more 0HP modules, a vactrol based VCA and a vactrol based low pass gate, offering more options for shaping the character of your patches without the cost in rackable modules.

What external devices are you using with your modular system? Tell us about it in the comments!

Chirping with the Moffenzeef Kriket

Moffenzeef Modular is known for the sometimes odd, quirky approach to Eurorack design, and Kriket is no exception. A strange device at first glance, Kriket is an interesting percussion module, generating anything from cowbells to snares to castanets.

Moffenzeef (who just opened their new online web shop!!!) generally has some fairly complicated modules, but modules that have some clear definition. The GMO operates as a sample or wavetable voice, with start and end point controls for the audio clip (head and tail, as the case may be). Deviant is a dirty random stepped module, fairly straight forward. Kriket, however, might leave you wondering, what is this for?

The module is effectively 4 oscillators running through 4 vcas, summed from to the output. Each voice includes a cv input to control the amp, and a knob to control frequency. A strange arrangement for most modular oscillators, where most might expect cv control of the pitch! However, pitch control comes in the form of the Kriket input at the bottom of the module. When voltage is sent to this input, a vactrol on the back of the module is illuminated, raising the pitch of the 4 oscillators.

Kriket can be gated to open and close the oscillator voices, creating tonal results. However, things start getting interesting when shorter pulse widths are used. Triggering the channels may be the best method to getting tight, popcorn-y percussive sounds. When the Kriket input triggered, these poppy, clicky sounds take on entirely new forms, becoming laser like zaps and snaps. Send in some alternating currents, and the Kriket input starts frequency modulating the pitch, shaping entirely different and complex warbles and hums.

Kriket may be best served with an actual envelope and vca following the mix output, for more shaping options. While this module may seem strange and simple, it begs to be tweaked in any way, shape or form.

How are you getting more complicated percussion sounds in your Eurorack system? Tell us about it in the comments!!

Troika From Instruo Eurorack Triple Oscillator

The first module from Glasgow-based maker Instruo, Troika appears fairly simple at first glance, with 3 nearly identical oscillators contained in a single module. However, a closer look reveals some interesting depth to this device, making it a powerful tool for classic subtractive sounds or complex tone shaping.

Troika has three individual oscillators, each with independent coarse and fine tuning controls ranging from LFO to supersonic frequencies, 1 volt per octave cv inputs, sync cv inputs and linear fm inputs with attenuators. Each oscillator has a dedicated output port, as well as a level knob to control the signal level to the summed mix out. The 1 volt per octave control for Oscillators 2 and 3 can be linked to the oscillator 1 1v/oct cv control using the by flipping the switches along the left side of the module into the down position, for key tracking and unison performance.

The waveform sections on each voice are each unique, despite the similar appearance. The first oscillator includes the 4 basic wave shapes, crossfading between either sine and triangle shapes, or square and saw. The second channel contains the same shapes, however this time the shapes are switched, crossfading instead between sine and square, or triangle and saw. The third oscillator crossfades between sine and saw, or switches to a pulse wave with control over the pulsewidth via knob or cv.

Troika really comes to life when you start patching the outputs back to the inputs. Since the oscillators can dip down to low frequencies, we can use them as modulation sources for the linear FM inputs on the other channels. In the video, I use oscillator 3 as a modulation oscillator, turning the level knob down so the low frequencies do not pass out of the mix out. The dedicated channel 3 output is not attenuated by the level knob, so I route it to the channel 1 linear FM input, slightly adjusting the FM knob to create some vibrato. As the oscillator 3 frequency and the linear FM knob rise, more sideband frequencies are generated, creating gorgeous atonal results.

The sync inputs are also incredibly useful for shaping complex harmonic content in Troika. Routing one dedicated oscillator output to another channel sync input, forces the synced oscillator to restart it’s wave cycle whenever the leading oscillator wave cycle rises in voltage. This causes the synced oscillator to generate musical harmonics, while retaining a similar pitch to the leading oscillator.

Troika can create incredibly complex tones when you begin to combine these many functions or incorporate a few external modules, from Moog-style layering to additive klangs. What are you using to generate complex tones in your system?

Radio Music Adds Pitch Control & Wave Files

Radio Music from Music Thing Modular is one of the more popular DIY projects in Eurorack, for it’s fairly simple build and extremely useful functionality. A new update has added some long awaited features including wave file support, a 1 volt per octave tuning option and more…

It’s been a good year for Radio Music owners. A few months ago, the new Chord Organ alternate firmware was announced by Tom Whitwell, developer of this and other modules under the brand Music Thing Modular. Now, a new beta firmware for the Radio Music has been released with a number of new and exciting features that make this device even more of a bargain, perhaps even a force to be reckoned with.

One of the most obvious and outstanding feature upgrades is support for standard wave audio files. Until now, replacing the samples on the module was a cumbersome process, involving persnickety naming conventions and rarely used RAW audio files. This meant loading files into Audacity or a similar sample editor to convert them one at a time, or using a shaky batch conversion process.

Now you have access to virtually any wave file, including all of those sample libraries that have been taking up disk drive space, or those fresh field recordings you made on the way to your modular gig… Or our student created open source sample library, the Voltage Control Lab Sound Study!

Another massive upgrade in this latest firmware version, the Start knob (which has traditionally been used to control the start position of the current sample) can be repurposed to instead control the pitch of the sample. Similar to other sample players in Eurorack, Radio Music can now perform 1 volt per octave pitch tracking on the samples with nearly a 2 octave range above and below the original tuning of the file.

There are even more added features in this beta, including better handling of audio rate triggering (up to a certain rate) among other fixes. Moreover, two very useful websites have been created to help navigate the modes for both Radio Music and Chord Organ. Polyfather.com offers a centralized location to download the most current firmware, as well as edit and then download the critical settings files that the module needs.

What will be the next adventure for Radio Music? If you dream up some wild use, the module is open source so you can re-imagine it yourself!

What modules would you like to see us discuss in the future? Let us know in the comments!

MSG Expansion Chips for Moffenzeef Muskrat

A couple of weeks ago, Ross Fish from Moffenzeef Modular sent us the new Muskrat module, a dirty percussion voice based on his MSG experimental sound box. This week, we tested the MSG expansion chips, 5 additional firmware versions that can be swapped out of the Muskrat to dramatically alter it’s functionality.

The Muskrat is already an amazing synth, but the MSG expansion chips each provide a new view into the potential of this module. The additional chips contain different firmware code, adding to the existing wavetable and phase distortion techniques on the original chip with frequency modulation, amplitude modulation, phase modulation, wavetable synthesis with amplitude modulation and granular synth.

The F chip performs frequency modulation using two internal oscillators, a carrier and a modulator. The scratch control modulates the FM index or the amplitude of the modulator, while dig controls the rate of the modulator with the switch at the bottom toggling between LFO and audio rate modulation. The carrier pitch is controlled by the chew knob, which acts as the main pitch knob for every mode. The bang input envelope follower and the tail and envelope range switch act the same in every mode as well, triggering and attenuating the voice. The A or amplitude modulation chip works in a similar way, with the scratch knob acting as a detune function for the modulator voice. This chips can generate some really nice atonal results.

The phase modulation chip, indicated by the P on the chip is a bit different. The Muskrat switch swaps between a grungy triangle wave and a squished sawtooth wave, while the scratch knob acts as a bit shifter generating some gritty high end frequencies. The dig knob controls rough phase shifting which tends to sound like octave transposition, or different intervals when bit shifted.

The wavetable with AM mode is very similar to the original firmware, but slightly less aggressive. Instead of wavetable phase distortion and folding, the wavetable is amplitude modulated, with the rate of modulation controllable via the scratch knob. The Muskrat switch toggles between LFO and audio rate modulation.

The granular chip, marked with a G, is wild. The module chooses from a collection of short samples selected by the dig knob, looping the sample with control over loop length (aka grain size) via the scratch knob. The bottom switch reverses the grain. This one can create some really glitchy, vocal style tones. Some real magic here.

These chips, originally intended for the MSG pocket synth, can expand this single, unique module into 5 additional modules. The real trouble is picking which one is your favorite…

What modules would you like to see us cover in future videos? Tell us in the comments!