One might be forgiven for thinking there is little that hasn’t been done with the humble multimode filter, but Patching Panda have a binaural twist for you. The Moon Phase is a stereo filter which allows different filter modes for the left and right channels, and then messes with the dimensions of space by applying mid‑side processing afterwards.
Housed in a silky black 14HP module, everything revolves around two 12dB/octave analogue multimode filters, one for the left channel and one for the right. In the centre of the module is a button which rotates around the various filter‑type combinations (or moon phases). The button changes both filter types simultaneously, so they are always controlled as a pair. For example, you might have a band‑pass on the left and a high‑pass on the right, or low‑pass on the left and a band‑pass on the right, or two low‑pass, and so on. There are eight combinations to choose from and the labelling on the front panel, along with a hot pink LED to show which is selected, makes it very clear.
There are separate inputs for left and right. For mono signals, the left input is normalled to the right. There is a gain pot for each input so you can overdrive the filter, or back off for a cleaner sound. Both filters share a cutoff and resonance control, with a Span control separating the frequencies between the two. The stereo imager balances the Mid and Sides signals post filter. This allows anything from a pure mono signal to only the stereo content. The essence of Moon Phase is really this combination of different filters on the left and right channels, and the Mid/Sides processing afterwards.
There’s plenty of CV control too. Frequency, resonance, span, mid/sides imager, and the filter modes all have CV inputs with the filter frequency input getting its own attenuvertor as well. The Mode input is a special case. It’s a trigger input, so any trigger received here will move the filter modes to the next ‘moon phase’ in a clockwise direction, just like the central button. Stepping through modes is good fun in a sequencing environment, but I found myself wishing for a continuous CV input, which would have allowed direct selection of modes without having to step through the others in‑between.
Moon Phase makes it easy to create swirling, shifting stereo panoramas from just about any input source.
The filter itself has a fairly clean character. During my initial explorations, I wasn’t sure if it was analogue or digital (it’s analogue). The resonance has a vocal quality to it and with its ability to mix filter types, it’s great for creating formant timbres. It doesn’t self‑resonate.
The stereo abilities are the main attraction here. Moon Phase makes it easy to create swirling, shifting stereo panoramas from just about any input source. With creative use of the CV inputs, employing LFOs, envelopes and audio rate signals, the resulting stereo signal can sound wonderful and complex. I enjoyed using it to process wet effects signals, while keeping the dry signal mono. Moon Phase was a great source of stereo percussion too, employing sequenced envelopes for the filter cutoff, resonance and span whilst stepping through the filter modes using the Mode trigger input. Modular stereo processing seems to be in fashion right now and Moon Phase proves that even the standard multimode filter can produce complex new sounds with a fresh stereo perspective. It should offer something new to even those with many filters in their rack.