5U Synthesizer Modules

This section contains modules that can be used to modify the frequency spectrum of incoming waveforms under voltage control, to modify the overall distribution of fundamental or harmonic components or to emphasize or remove specific frequency bands.

PM Resonator™ - 3 Channel Formant Filter

The PM Resonator™ is a recreation of the formant filter section of a Polymoog™ synthesizer in a standard MU double-width modular panel.

GMS-294A 4 Pole Low Pass  Filter

A transistor ladder made with vintage transistors gives the same sonic character to the GMS-294A Four Pole Low Pass filter recreation that the original 904A Four Pole Low Pass filter possesses.

GMS-209 State Variable Filter

This state variable 2 pole (12 dB/Octave) filter has two signal inputs mixed at unity gain with low pass, bandpass, and high pass outputs.

GMS-272MU Parametric Equalizer

The GMS-272MU Parametric Equalizer offers sound shaping ability similar to those found in studio mixing desks.

GMS-214 Multimode Filter

The GMS-214 Multimode Filter can select from one of fifteen possible combinations of number of poles and filter types. It also has voltage controlled resonance.


We produce electronic synthesizer modules in the two most popular formats, MU (Moog compatible 5U) and EU (Eurorack compatible 3U). A wide range of voltage controlled modules including oscillators, amplifiers, mixers, envelope generators, special effects units, wave generators, filters, power systems and cases allow users complete freedom to configure any desired electronic music instrument.


Grove Audio builds microphones, preamplifiers, equalizers, compressors and other professional audio equipment for performance and studio use. We build units in popular formats such as 19 inch rack mount and 500 series 3U modules. We can also produce custom designs on request. Contact us for a consultation.


You can explore all of our products, download spec sheets, and purchase our products in the Grove Audio Synth Store. You can also learn about our periodic specials and new product introductions. Click the button below to go directly to the store.

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Grove Audio has been manufacturing professional recording and modularized electronics for musicians and performers since 1995.