904A Low Pass Filter

Aion Modular 904A

Aion Modular expands their line of Eurorack-format Moog clones with a module inspired by the greatest filter of all time: the Moog 904A Voltage Controlled Low Pass Filter. Not to be confused with the Minimoog's lowpass filter, the 904A is the original source of a sound that has come (to many) to define the word "synthesizer": a huge-sounding 24dB lowpass with buttery resonance and a warmth unmatched by anything that has followed.

On the front panel, the 904A is simple: three selectable frequency ranges (with range 2 being the typical "audio" range), Regeneration control (resonance), Fixed Control Voltage (filter cutoff frequency), and three CV inputs. With a sound like this, though, no more bells or whistles are required—plug in a mix of waves (perhaps combined with a CP3), slowly open the filter, and listen to years of rich history gradually peek through. And Aion's 904A isn't a cheap imitation—it is as close to the original as a Eurorack module has ever come.

Note: combining the 904A with a 904B High Pass Filter and 904C Filter Coupler gives you the same triple-threat filter arrangement found in many original Moog systems—capable of variable-width band reject, bandpass, and countless remarkable filtering effects.

904A Features

• Faithful Eurorack-format clone of the the greatest filter of all time: the Moog Modular 904A Low Pass Filter
• Classic 24dB response
• 1V/Oct operation with three CV inputs
• Continuously variable Regeneration (resonance)
• Fixed Control Voltage knob offers 12-octave sweep
• Three selectable frequency ranges: 1Hz–5kHz, 4Hz–20kHz, 16–80kHz