MATRIXSYNTH: Classic vibes and analog mojo in 6 drum modules from GRB Instruments

video upload by bajjjan records

"6 New GRB Instruments drums for eurorack.
The modular analog drum machine with a classic vibes is almost ready!
There are 11 patterns/jams in this video."

GRB Basic Kick & GRB Hi-Hat || Modular DEMO

video upload by bajjjan records

CYMBAL

Sound is synthesized by a system of oscillators based on Schmitt triggers, that recreates the classic, complex sound of an analog cymbal. The sound is synthesized by a system of oscillators based on Schmitt triggers, operating at different frequencies. The mixing of these signals creates the rich, chaotic, and metallic spectrum.

You have direct control over the resulting texture. The TUNE knob shifts the overall frequency range of the metallic noise, while DECAY sets the length of the sound's wash and sizzle. The TONE control further shapes the character of the ringing, allowing you to fine-tune the brightness and timbre. This combination of controls lets you sculpt everything from a short, bright metallic click to a long, decaying noise.

For dynamic performance, the module features an ACC input (0V to +5V) to modulate the accent level and is triggered via the standard GATE input (+5V to +12V). The final, complex cymbal sound is available at the OUT jack.

MARACAS

At its core is a source of white noise, shaped by a envelope generator.

The ATTACK knob sets the sharpness of the initial hit, the DECAY control determines the length of the rattle, and the TONE parameter filters the white noise spectrum, shifting it from a dark, grainy texture to a bright, sandy hiss. This allows you to create a wide range of sounds — from a subtle, tactile rustle to a sharp, noisy accent.

DECAY time can be modulated via the CV input (0V to +5V), and dynamic accents are applied through the ACC input (0V to +5V). The module is triggered by a GATE signal (+5V to +12V), with the final audio available at the OUT jack.

RIMSHOT/CLAVES

Synthesizing two distinct types of percussion using a classic analog approach: the sharp crack of a rimshot (snare drum rim hit) and the dry, wooden click of claves. In both modes, the sound is based on a tonal impulse generated by a resonant circuit. The RIMSHOT/CLAVES switch changes the voice architecture, altering the filtering and envelope parameters of this impulse.

In RIMSHOT mode, the circuit produces a short, bright click with a rich overtone structure. In CLAVES mode, it generates a longer, more focused, and purer tone with a precise attack. The shared TUNE control allows you to adjust the fundamental pitch of the sound in both modes, enabling you to seamlessly fit it into the harmonic context of your composition.

TUNE can be modulated via the CV input (0V to +5V), and dynamic accents are applied through the ACC input (0V to +5V). The module is triggered via the GATE input (+5V to +12V), with the final audio available at the OUT jack.

SNARE DRUM

Sound is built from two core components: a bridged-T network, which acts as a damped oscillator to generate the tonal 'body' of the snare when excited by a pulse, and a filtered white noise generator, responsible for the characteristic 'snap' and texture. This architecture provides independent control over each element.

You have direct command over the tonal via TUNE, sharpness of the initial hit ATTACK, and DECAY length of the tonal decay. The noise component is precisely shaped by the SNAPPY control, which sets its decay time. This separate control over pitch, attack, tonal decay, and noise duration unlocks a wide palette of sounds — from percussive clicks to full, noisy snare hits.

For modular integration, the tonal frequency and noise decay can be modulated via their respective CV inputs (0V to +5V). Dynamic accents are applied through the ACC input (0V to +5V), and the module is triggered via the GATE input (+5V to +12V). The final mixed signal is available at the main OUT, while the raw white noise is also accessible separately at the WN OUT for further processing.

BASS DRUM

The core sound is generated by a bridged-T network — a resonant band-pass filter that acts as a damped oscillator when excited by a trigger pulse. Its main frequency is set by the TUNE knob. Envelope generator modulates this network, where DEPTH controls the range of the initial pitch sweep, PUNCH sets its recovery speed, and DECAY determines the overall length of the sound. The character is shaped by the TONE control, a low-pass filter that attenuates the high-frequency attack click, and by the DRIVE circuit with its HARD/SOFT intensity switch, which adds variable saturation.

The CV input allows for external voltage control (0V to +5V) of the main frequency (TUNE), the ACC input (0V to +5V) modulates the accent level, and the GATE input (+5V to +12V) receives the trigger signal. The processed audio is available at the OUT jack.

This design offers versatile sound shaping, suitable for everything from subtle, deep kicks to aggressive, distorted tones.

BASIC KICK Classic analog kick

Roland Style Bass Drum. You can make a kick like on the 606/808/909. This module incorporates everything we love so much about classic analog kicks. And even more...

HI-HATS

Sound originates from a system of oscillators based on Schmitt triggers, generating a harmonically rich signal with a metallic character. This signal is then shaped by a resonant filter and amplifier with envelope, get the distinctive "tssss..." sound.

The module provides individual control over the closed (CH) and open (OH) hi-hat sounds. The TONE knob adjusts the brightness and character of the metallic ring, while DECAY independently sets the length for each type of hi-hat. The MAIN TUNE control shifts the overall frequency spectrum of the noise source. The feature is the CHOKE function, which emulates a hi-hat pedal by muting the open hat sound whenever a closed hat is triggered, enabling authentic, dynamic rhythmic patterns from tight accents to evolving textural backgrounds.

DECAY time can be modulated via the CV input (0V to +5V), and dynamic accents are applied through the ACC input (0V to +5V). The module is triggered via the GATE input (+5V to +12V). The processed sounds are available at two separate outputs: CH OUT for the closed hi-hat and OH OUT for the open hi-hat, allowing for individual mixing or processing.