The Sherman Filterbank defies categorization. Lying somewhere between the average filter processor and a full-blown analog synth, the Filterbank is both and neither. The Filterbank can transform small tones into huge menacing sounds, and it can twist and deform beautiful patches or samples into a delightfully distorted lo-fi din. Although it's not a studio necessity like a good compressor or preamp, the Filterbank is something that you'd end up using a lot if you had one.
Sherman ceased production of the original Filterbank at the beginning of 2001, replacing it with the Sherman Filterbank 2. Fortunately, the Filterbank 2 offers all of the same features and sounds as its predecessor, with the addition of five three-way switches, two LEDs and a pedal input. Sherman also reduced the output noise to enhance the overall sound quality. Like the original version, the Filterbank 2's knobs are color-coded to make it easier to identify which function you are adjusting, but instead of being housed in a cream-colored case, it now comes in an industrial gray box.
TWO FILTERS ARE BETTER THAN ONE
In essence, the Sherman Filterbank 2 consists of two synchable multimode 12dB filters, a preamp, two envelope generators, an envelope follower, two VCAs and an LFO. The lack of a VCO keeps the Filterbank from being a traditional synth and instead allows you to use any sound source — such as a synth, a sampler, a guitar, a drum machine or a miked instrument — in place of oscillators. The unit has 24 knobs and six switches for manipulating sounds, but it has no memory for saving settings. If you stumble across a sound you can't live without, you should record it immediately, as chances are you'll never be able to duplicate that exact sound again. However, the possibility of always stumbling upon a new sound is part of the Filterbank's allure.
The Filterbank's rear panel boasts 11 ¼-inch inputs and outputs and five MIDI jacks (one In, one Out and three Thrus). In addition to a mono audio input and output, the unit offers FM and AM inputs, a link input and output (for chaining multiple Filterbanks together to create a 48dB, 72dB or 96dB filter and so on), AR and ADSR trigger inputs, an ADSR output, a separate audio output for filter 1, and a pedal input for controlling bypass and the frequency of filter 1. Unfortunately, the Filterbank's knobs do not transmit MIDI (only two trigger notes, F#4 and A#4, on channel 16 are transmitted via the unit's MIDI Out), so you can't save your knob tweaks to a sequencer. However, you can trigger a wide variety of the Filterbank's functions and control various functions via an external MIDI controller or sequencer. If you want to duplicate any knob movements, you're best off recording your experiments in a sequencer. It's unclear why the unit has three MIDI Thrus, but at least it will save you from needing to buy an extra MIDI Thru box in the future.
The two filters operate in Parallel mode (as two separate filters) or in Serial mode (the output signal of filter 1 is routed into filter 2, enabling the Filterbank to operate as a 24dB filter); you can also crossfade anywhere between both modes. Unlike most filters in synths, samplers or stand-alone units — which provide high-, band- and lowpass switches — the filter curves for both filters are continuously variable from highpass to bandpass to lowpass settings. Both filters also include unique “correction” knobs that let you adjust each filter's output and enable the filters to operate as notch filters.
One particularly cool and unusual feature is the 12-position Harmonics switch included with filter 2. This switch lets you sync the filters and adjust the cutoff frequency of filter 2 to a fixed ratio (from equal tuning to four octaves down) to filter 1's cutoff frequency. Experimenting with this switch provides many fascinating tonal variations — much more than you'll ever get out of an ordinary filter.
Both filters' Frequency and Resonance controls cover a wide range, making it easy to generate extreme highs or lows that can quickly burn up your speaker coils. Sherman is up front about this: The back of the unit features a cartoon character that resembles Edvard Munch's “The Scream” and a warning to watch your speakers. Even after you've become accustomed to using the unit, it's best to proceed carefully and with caution because a few tiny knob adjustments can take the frequencies beyond the range of your hearing but not out of the range in which they'll blow your speakers. The greatest benefit of that range is that the Filterbank can help you pull frequencies out of tired old equipment that they never had in them before. If you're looking for a way to beef up the sounds of a drum machine or add vigor to a wimpy-sounding groovebox, the Filterbank is the only way to go.
The original Filterbank offers extremely versatile possibilities for creating new sounds, but the five new three-position switches on the Filterbank 2 expand those opportunities even more. Switches include high-frequency boost/cut, trigger sensitivity/limiting, +octave/+quint (an interval of a fifth) transpose, normal/low tracking and sawtooth wave-shape/AR-retriggering LFO settings. If you want the Filterbank 2 to operate exactly the same as the original unit, you simply need to position each switch to the center setting. The tracking and +quint functions work best with monophonic sound sources, but even the glitches created by running chords or samples of musical passages through these processes often generate musical, useful results — particularly if you're into tweaking sounds beyond recognition.
Indeed, the Sherman Filterbank 2 is best-suited for musicians and sound creators who prefer to deconstruct sounds rather than sweeten them. It is very easy to overdrive the Filterbank's analog circuitry by boosting the input level, resulting in some nasty, warm and complex sounds that scream. This is an organic-sounding distortion that complements the aggressive tones that the Filterbank generates. If you listen closely, you can hear subtle tone variations that shift over time, which can result in no two notes ever sounding exactly the same. If you're tired of the predictability of your digital virtual analog synth, the Filterbank can transform it into the analog beast you've always wanted it to be. It's no wonder that artists such as the Chemical Brothers, Chicks on Speed, Nine Inch Nails and Prodigy love their Filterbanks.
BEYOND THE BOX
Although uses for the Filterbank may not be immediately obvious, it takes only a little experimentation to realize some of its potential. Running a Roland 808 or 909 drum machine through the Filterbank can result in some incredibly huge-sounding drum patterns, and you've never really heard a TB-303 scream until you've tried processing one through a Filterbank. This is not a unit for engineers who like to process sounds by the book; rather, it is the perfect tool for creative thinkers who prefer to explore new possibilities and applications.
At a suggested list price of nearly $800, the Filterbank 2 is not cheap, especially compared to other filter processors. Although you can buy a pretty impressive synth for that price, the Filterbank is still a good value. I've owned an original Filterbank for more than four years, and I've used it on every recording I've made. Whenever my bass lines needed to sound bigger or my drum patterns demanded more variation and punch, I turned to the Filterbank, and it never let me down. But the Filterbank has probably been most useful for those occasions in which I've faced a blank canvas and needed to create a new sound to inspire me. In those cases, satisfaction has only been a knob-twist or two away.
Pros: Extremely versatile analog dual-filter processor. Generates an endless variety of rich, warm, complex tones. Incredibly extended frequency response.
Cons: No patch memory. Knobs don't transmit MIDI information. Frequencies can damage speakers.
Overall Rating: 4