Moonmodular 504 Low Pass Filter

Moog or modern? – The 504 is a traditional ladder-type circuit with switchable edge steepness. In detail, values between -6 dB and -24 dB per octave can be selected. The module’s cutoff frequency and resonance are manually adjustable plus there are several CV inputs. With the help of a jumper, a bass compensation can be activated. Thus, you have the choice between classic Moog character with thinned out bass range at high resonance settings or more modern, constantly fat sound.

The 504 VC Low Pass Filter is a classic, ladder-style circuit with some clever additions. The module’s cutoff and resonance parameters can be adjusted using potentiometers. In addition, there are two frequency CV inputs. One of them features a bipolar attenuator. A third CV input can be used to modulate the resonance. The 504’s edge steepness is determined by a three-way switch. However, in total there are four options. Two jumpers decide whether the module operates at -6 dB or -18 dB per octave in the middle position of the switch. The options always available are -12 dB and -24 dB per octave. Another jumper makes it possible to (de)activate the bass compensation of the filter. Thus, you can choose between classic Moog behavior, meaning the low frequency range drops more and more in amplitude while the resonance is increased, or a modern character without any loss in bass.