Studio Electronics Boomstar Modular System Modstar SE88 Filter Module

Originally debuted in their Omega Series synths and then repurposed for the Boomstar desktop modules, Studio Electronics SE88 is their version of the dual mode Yamaha CS-80 filter. They've twisted and turned the SE88 to 'unflatten the earth,' so to speak: the original CS-80 fed a high pass filter into a low pass filter, but with the SE88 you can select MODE 1's high pass or band reject to feed MODE 2's low pass or band pass, or patch it to reverse that path. The audio signal is completely controllable with input and output levels for each filter. Cherish and respect your filter's input gain stages for a smooth-yet-brassy sound, or shed your mercy to strike hard for boiling, snarling bite, even to the blackout/cutout point*; then — and only then — uniquely blend mode settings for the filter family values you prefer.

To get things merrily modulating, each filter employs attenuverters for frequency and resonance experimentation and decimation. While the SE88 does not self oscillate (Yamaha's didn't either), Studio Electronics did amp up the resonance level for full-throttle squelching. An additional master FM (frequency modulation) attenuverter-controlled level can feed both filters simultaneously, and tracking switches allow for individual keyboard response for each of the contrasting and complementary filter modes.

Of special note
Two audio paths are involved if you are running the '88 filter in series, so both input levels and the seeded output level of the first stage have to be taken into consideration if a clean sound is desired — either that or keep your resonance setting below 3:00 to avoid the fireworks. This beast's resonance is wide open, with no governor in place — hot-rodded — so expect voltaged chaos when you push it past its 'yama-clone' comfort zone.

• Module controls
• FREQUENCY MODE 1 knob: adjusts the frequency (cutoff) of Mode 1
• FM IN knob: adjusts the master frequency modulation input
• FREQUENCY MODE 2 knob: adjusts the frequency (cutoff) of Mode 2
• FM IN knob: adjusts the master frequency modulation input
• 2/3 / 1/3 TRACK switch: toggles tracking options for Mode 1
• FULL / HALF TRACK switch: toggles tracking options for Mode 2
• RESONANCE knob (left): adjusts the resonance of Mode 1's filter
• M1 FM knob: adjusts Mode 1's frequency modulation
• RESONANCE knob (right): adjusts the resonance of Mode 2's filter
• HP / BR switch: toggles between high pass and band reject filter modes for Mode 1
• LP / BP switch: toggles between low pass and band pass filter modes for Mode 2
• M1 RES CV knob: adjusts Mode 1's resonance control voltage
• M2 RES CV knob: adjusts Mode 2's resonance control voltage
• OUTPUT knob (left): Mode 1 audio attenuator
• M2 FM knob: adjusts Mode 2's frequency modulation
• OUTPUT knob (right): Mode 2 audio attenuator
• LEVEL knob (left): Mode 1 audio input attenuator
• LEVEL knob (right): Mode 2 audio input attenuator
• Patch points
  • 1 V/O input: one volt per octave control voltage input
  • FM IN input: frequency modulation control voltage input
  • M1 FM input: Mode 1 frequency modulation input
  • M2 FM input: Mode 2 frequency modulation input
  • M1 RES CV input: Mode 1 resonance control voltage input
  • M2 RES CV input: Mode 2 resonance control voltage input
  • M1 IN input: Mode 1 audio input
  • M1 OUT output: Mode 1 audio output
  • M2 IN input: Mode 2 audio input
  • M2 OUT output: Mode 2 audio output
• Physical specifications
• Size: 20hp
• Module depth: 39.7mm (with ribbon cable attached)
• Power usage: 42mA @ +12V, 42mA @ -12V

*BYSIB (Before You Send it Back)
This filter can be 'input driven' to the cutout/cutoff/blackout point, for angry, aggressive unpredictability and staggered, shell-shocked recovery. Studio Electronics wanted it that way; it’s perfectly harmless OpAmp smashing, for smashing good fun. Think 'traumatic movie scene after which an actor’s hearing momentarily disappears (extreme wooziness overtakes the balance of his senses—and camera work), high-pitched sounds follow, and then blessed normalcy of awareness and sensory perception gradually, grudgingly return.' That. No reboot necessary: just sweep the frequency counterclockwise until it snaps back to its 'right mind' and rein in the input and resonance levels—resonance levels below 9:00 are safe, unless of course you want 'that' to keep happening. Taunting the edge is entertaining, too!