Dupertuis Electronique SA

Audiophile Circuits League DISCRETE CORE LADDER VCF
Width 18 HP
Audiophile Circuits League Discrete Core Ladder VCF is a beautifully liquid sounding Moog-inspired transistor ladder design filter, with four outputs (6dB, 12dB, 18db, and 24db). We believe ours sounds fantastic, but there are many great sounding filter modules available, so we wanted to do something new, and designed a filter that addresses traditional limitations and offers new possibilities.
Our VCF features a ‘BOOST’ control. In most ladder VCF designs, the lower frequencies get attenuated (i.e the bass is lost), when you dial up the resonance. BOOST restores the low frequencies, boosting them at high resonance settings, allowing you to play extreme squealing basslines that are still… basslines.
Furthermore, our Discrete Core Ladder VCF features four separate buffered outputs for 6dB, 12dB, 18dB, and 24dB/octave sloped filters. This offers many many advantages over a simple switch selecting one slope setting or another.
Each of the outputs taps consecutively into the signal path as it is progressively filtered, and all of them can be routed and used separately… and simultaneously. Things get interesting then, because each stage is phase shifted by 90° from the previous. This offers very creative possibilities for combining these signals, as when you combine phase-shifted signals, some frequencies are cancelled. When combining them using a mixer that allows you to invert the waveforms of some of these, you can create fascinating bandpass filters, and everything in between low- and high-pass filters. It is similar to Oberheim’s Expander Filter, but with its own unique character, since our filter is modelled on a Moog design.
We have not limited ourselves to features, of course: Signal path is key to making a filter sound fantastic. A fully discrete, low noise, low distortion audio path is used throughout the circuitry. And we designed it to saturate at exactly the point our experience has taught us responds best, and works well with other modules. When approaching 8V PP (Peak-to-Peak), the filter will create an awesome creamy and compressed sound that bends and evolves ever more as you push the input signal harder. And yet at lower signal levels, low distortion discrete buffers ensure the overall distortion of the signal is quite low, enabling a very clean sine wave when the filter is self-oscillating a little.
The end result offers the lush characteristics of a Moog filter, but with creative and practical possibilities unique to our VCF.