EM-402 Sunless City Transistor Ladder Filter is an exceptional transistor-based cascade ladder low-pass filter. The module attenuates frequencies above the fixed control voltage cutoff point at a rate of 24 dB per octave and 18 dB per octave. The respective four-pole and three-pole ladder positions can be selected via the Slope Type slide switch.
The VCF’s two signal inputs are attenuated using the independent Drive controls. Increasing these attenuators towards maximum level can produce gently overdriven sound characteristics.
The module creates widely varying timbres utilizing classic subtractive synthesis techniques. The design features a robust exponential current converter and temperature compensation circuit, which produces precise voltage tracking.
The principal low-pass frequency is determined by the combination of the Cutoff Frequency position and the control input signals—the latter of which are denoted as 1 V / Oct and Variable. The variable Frequency Modulation level can be attenuated via the dedicated F.M. slide potentiometer.
The filter’s cutoff ranges from 10 Hz to 35 KHz.
The Response control varies the filter’s resonance. Increasing this parameter will narrow and boost the strength of the cutoff peak, while simultaneously decrease the amplitude of the lower frequencies.
At relatively high resonance settings, varying the control input voltages will emphasize the upper harmonics of the sound—to the point of selecting pitches in counterpoint to the movement of the signal frequency itself.
Significantly increasing the Response level will lead to uninhibited self-oscillation, wherein the oscillation will permeate well over the totality of the audio bandwidth. This regeneration event results in forming a ‘clean’ sine waveform, which can be further utilized for ‘ping’ filtering, and/or for generating dynamic percussive patterns.
Specifications:
Model: EM-402
SKU: 400-0402
Dimensions: 12 HP (3U)
Skiff: 28mm
Panel: 2.00 mm Anodized Aluminum
Power: +/- 12 V | 50 mA
1-Year Limited Warranty
Notice to customer: Please use the enclosed IDC connector. Problems arising from use of another connector will not be covered and may void your warranty. Modifications or alterations to your module will void the warranty as well. For assistance please contact .
circuits.la/warranty
![LA Circuits - EM-402 Sunless City [Transistor Ladder Filter]](http://www.noisebug.net/cdn/shop/files/SunlessCity.png?v=1707246582)