Studio Electronics Boomstar Modular System Modstar 4075 Filter Module

Studio Electronics 4075 filter is a voltage-controlled discrete analog 24 dB/octave cascaded transconductance low pass filter employing hand-matched transistors. In its lowest FREQUENCY setting it shaves off higher frequency harmonics; its RESONANCE or Q circuit pushes those harmonics past the self-oscillation boiling point, projecting a thumpy, thrashing squeal with explosive low- to mid-range power and depth. The design is actually pulled from the four-pole ARP 4072 (better: more parts and trims), sans the 12kHz design flaw which hamstrung the original's high end. The 4075 name has stuck, though — no correcting Studio Electronics' little misnomer.

The 4075 filter has been the most requested of the Boomstar filter models, perhaps owing to its uniqueness. Has there ever been a better match for a square wave? It weaves dreams with 'glidey' 70s basslines, is a natural in the lead department and feels as if a temper tantrum simmers a mere micron beneath its veneer of faux respectability. Aggressive and articulate, this fresh ARP can snap out punishing kick drum sounds as well as color with bright, edgy, stringy tones for essential arpeggiations.

Potentiometer potential
Seven attenuation pots control the FREQUENCY, RESONANCE, FREQ CV 1, RESO CV, FREQ CV 2, INPUT and OUTPUT, delivering smooth, detailed and complex expression.

Switch it up
Classic Minimoog FULL and HALF strength filter frequency keyboard/voltage tracking for rounder low end with brilliant highs.

Patch it up
Seven patch points — 1 V/O, FREQ CV 1, FREQ CV 2, RESO CV, INPUT and 2x OUTPUT — direct the deepest manipulation.

• Module controls
• FREQUENCY knob: adjusts the frequency (or 'cutoff') of the filter.
• RESONANCE knob: adjusts the resonance (or 'Q') of the filter. (From 7:00 (0) position to 9:00, Studio Electronics' 'Negative Resonance Saturation' adds beefiness, boosting the waveform amplitude and taming waveform transients; set to 9:00 to achieve the cleanest tone possible.)
• FULL/HALF TRACK switch: switch between full and half keyboard/voltage tracking.
• FREQ CV 1 knob: frequency control voltage 1 input attenuverters.
• RESO CV knob: resonance control voltage input attenuverters.
• FREQ CV 2 knob: frequency control voltage 2 input attenuverters.
• INPUT knob: adjusts the audio input level.
• OUTPUT knob: adjusts the audio output level.
• Patch points
• 1 V/O input: one volt per octave control voltage input.
• FREQ CV 1 input: frequency control voltage 1 input.
• FREQ CV 2 input: frequency control voltage 2 input.
• RESO CV input: resonance control voltage input.
• INPUT: audio input.
• OUTPUT (×2): audio outputs.
• Physical specifications
• Size: 12hp
• Module depth: 39.7mm (with ribbon cable attached)
• Power usage: 23mA @ +12V, 30mA @ -12V