Analogue Solutions has upped the ante in the stompbox filter wars by introducing the Phobos Filtered Coffee ($325). The feature-packed single-rackspace unit is an accurate-sounding analog emulation of the filter section from the venerable Korg MS-20 synthesizer.
The Filtered Coffee is housed in a plastic case, and its sturdy metal front panel is tightly packed with controls. The unit's 15 knobs have a rubberized coating that makes them easy to grasp and tweak. All the switches and pots are solidly mounted and have no wiggle or play. Some knobs also operate as switches when you pull them, allowing you to invert control voltage (CV) sources.
Fourteen ¼-inch jacks provide three audio inputs, three audio outputs, six CV inputs, and two CV outputs. By providing the means to route outputs to inputs, the rear panel permits the sort of flexibility you would expect in a modular synthesizer. The CV inputs allow you to manipulate audio signals using expression pedals and external control sources such as analog synth modules. A 15 VAC wall-wart adapter is included.
Grounds for Examination
A lowpass and a highpass filter are at the heart of the Filtered Coffee. When you insert a signal into the line-level Signal In jack, it's routed to both filters. Fortunately, a Signal In Thru jack lets you reroute the main audio input to the lowpass filter or voltage-controlled amplifier (VCA). Alternatively, you can insert a signal directly into the lowpass and VCA audio inputs. (The Signal In Thru and CV outputs are also useful if you're processing in stereo with a pair of units.)
Both filters sound quiet and musical, and both let you turn up the resonance to the point of self-oscillation. The Cutoff controls for both filters have limited ranges; consequently, sweeping the frequency above audibility requires the use of a modulation source. Lamentably, you can't modulate the highpass filter below its minimum cutoff of about 140 Hz, which means that any deep bass in your source will be attenuated, regardless of the cutoff and modulation settings. That also means you can't set the highpass filter's frequency low enough to boost bass drums and deep bass lines with high resonance settings. However, you can simply bypass the highpass filter by patching audio directly to the lowpass filter, but that's just not as interesting as using two filters simultaneously.
The Filtered Coffee contains an envelope follower that tracks any audio input's changes in level. Two triangle-wave LFOs provide internal modulation sources. All external CV inputs are summed with the internal modulation paths.
I appreciated the inclusion of multiple modulation sources with individual attenuation and inversion controls. Each filter has two three-position switches for selecting two modulation sources, CV1 and CV2. The first switch toggles between LFO1 and Pedal, and the second toggles between the envelope follower and LFO2; each switch's center position turns modulation off. You can attenuate modulation depth with the CV1 and CV2 Level knobs.
Pulling out a CV Level pot inverts a modulation source's signal. If you select LFO2 on both filters and invert the signal from one, you can create a cyclic bandpass response with a fluctuating width. Then, to punch things up even further, you can add pedal modulation to one filter and LFO1 modulation to the other. You can also apply LFO modulation to the VCA for tremolo effects.
A Fine Cuppa Joe!
Although it is more expensive than some standalone filters, the Filtered Coffee is a useful tool for creating satisfying musical effects without the need for any additional gear. It adds plenty of analog character and motion to almost any type of source material. Effects such as audio-rate FM, for example, impart a wonderfully gritty character to your sounds. The unit's manipulation and mangling of audio can be simple or drastic, and its capabilities should provide you with plenty of new ideas and unusual results. If you're searching for a means to spice up your sound, be sure to check out the Phobos Filtered Coffee.