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GMS294A 4 Pole Low Pass

Transistor Ladder Filter for Eurorack

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.

 A rotary switch selects the frequency range and a panel fine tune potentiometer allow setting the exact filter frequency. Gain controls are provided for the audio input and the frequency voltage control inputs.

The EU version is housed in a 12 HP (2.4 inch wide by 5.04 inch high) panel with Eurorack compatible power connector.


Technical Specifications

Filter topology
4 pole low pass transistor ladder filter
24dB per octave overall

Low Frequency Range
1Hz - 5KHz

Medium Frequency Range
4Hz - 20KHz

High Frequency Range
16Hz - 50KHz

Typical Input Impedance
100K Ohms

Typical Output Impedance
1K Ohms (short circuit protection)

Frequency control inputs
2 - Input 1 fixed 1V/Octave,
Input 2 with attenuator

Module Power
+12 Volts 35 mA.
-12 Volts 25 mA.

Module Size
Panel height - 5.03 inches (128 mm)
Panel width - 2.4 inches (61 mm)
Depth (behind panel) 2.1 inches (53 mm)

Kit - $165.00

Assembled - 234.00


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. 


A wide range of electronic parts, kits, tools and accesories is available on the Strange Hardware site. Fast order response, free shipping specials and prompt service will get you the parts you need for your building, restoration or repair projects. You will find high tech hardware sure to inspire the inventor in you. 


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.


256 N Main St.
Cottage Grove WI 53527

Phone: 608 886-6503

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