SEM

Voltage Controlled State Variable Filter

Sensei Caswell:
"Our SEM is known as a 'Voltage Controlled State Variable Filter' because it provides simultaneous high pass, low pass, and band pass outputs, all with a 12 dB/oct slope. The notch is the inverse of the bandpass, achieved by summing the Low Pass and high pass outputs. This version is a combination of the original SEM filter and the newer design from the OBX, along with improvements by SE. It has a modest current draw, which it pulls evenly from the plus and minus rails."

If you've heard the SEM filter in our Boomstar desktop: / you also know that this 12 dB favorite is "capable of lighter, more subtle tones than the other three models. This isn't to suggest the filter's Low Pass mode can't cater for fat and punchy, because it can." - Paul Nagle, Sound on Sound. Looking for deeply gratifying tonal variance and this emotional warmth? Try: —our friend Fred Falke's favorite—it can reach into your head and heart, and stay as long as desired. Thank you Lord Tom Oberheim for this marvelous design/template from which we were able to work our very own Studio Electronics eurorack filter enchantments—we do like to hit our SEM a bit harder though ;)

Potentiometer Potential
Three attenuverter and four attenuation pots control the FREQUENCY, RESONANCE, FREQ CV 1, RESO CV, LP HP, INPUT and OUTPUT, delivering smooth, detailed, and complex expression.

Switch it Up
FULL and HALF strength filter frequency keyboard/voltage tracking, and BP / LP-HP modes.

Patch it Up
Seven patch points: 1 V/O, FREQ CV 1, FREQ CV 2, RESO CV, INPUT, BP LP-HP, and OUTPUT direct the deepest manipulation.

All Controls and Patch Points
FREQUENCY – Adjusts the frequency, or cut-off of the filter.
RESONANCE – Adjusts the resonance of the filter.
FULL HALF TRACK – Switch between full and half keyboard/voltage tracking.
FREQ CV 1 – Frequency control voltage 1 input attenuverter.
RESO CV – Resonance control voltage input attenuverter.*
LP HP – Low Pass / High Pass attenuverter.
INPUT – Adjusts the audio input.
OUTPUT – Adjusts the audio output.
1 V/O – One volt per octave control voltage input.
FREQ CV 1 – Frequency control voltage 1 input.
FREQ CV 2 – Frequency control voltage 2 input.
RESO CV – Resonance control voltage input.
INPUT – Audio input.
BP LP-HP – Switch between Band Pass and Low Pass - High Pass modes.
OUTPUT – Audio output.

BYSIB (before you send it back)
This filter (and the SE88) can be ‘input driven’ to the cutout/cutoff/blackout point, for angry, aggressive unpredictability, and staggered, shell-shocked recovery. We 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 forward and back, and pull back the input level, unless of course you want "that" to keep happening. Taunting the edge is entertaining too.

• From 7:00 (0) to 9:00 our “Negative Resonance Saturation” adds beefiness, boosting the waveform amplitude and taming waveform transients (most pronounced in the 3003 filter): set to 9:00 to achieve the cleanest tone possible.

http://www.studioelectronics.com/products/synths/boomstar-modular/sem/#modstar