FILTERLOPE is an analog-flavoured filter effect with built-in envelope follower. It was inspired by the vintage “auto-wah” designs prevalent in the 70s and 80s, but we’ve added a few twists of our own!

FILTERLOPE can be used as a standard lowpass filter driven by its own LFO, or the filter sweep can be set to follow the gain of the input signal, or an external sidechain.

FILTERLOPE is a stereo in / out module. When either input is used on its own, it will be routed to both outputs.

FREQ sets the start or centre frequency depending on the mode of operation. In LFO mode, the filter’s cutoff frequency will be swept either side of this frequency according to the SWEEP and RATE settings. In ENV mode, FREQ sets the initial frequency and when the envelope kicks in, the frequency will be swept up or down according to the SWEEP and ENV settings.

PEAK sets the resonance of the lowpass filter. Increasing this control results in a more pronounced / obvious effect.

SWEEP determines the range of the filter frequency sweep in both LFO and ENV mode.

The LFO / ENV switch determines whether FILTERLOPE uses its own LFO (left position) to sweep across the frequency range (set by SWEEP) or whether to follow the envelope (ENV) of an incoming signal (right position).

RATE varies the LFO rate from 0.01 to 5.0 Hz.

The DRIFT button, when turned on will introduce gradual variation to the LFO speed so the repeating cycle is not obvious and locked to a set time. This can be a useful effect when used with slower LFO rates.

SENSITIVITY varies the threshold of the envelope follower and determines the amount of effect applied, according to the level of the input signal. When used in stereo, the average of the left and right channels is fed into the envelope follower.

The INVERT button, when turned on inverts the response of the envelope follower so that stronger signals close the filter (downwards sweep) instead of opening it (upwards sweep).

The LED between the RATE and SENSITIVITY knobs indicates the amount of effect or a representation of the envelope follower depending on the LFO / ENV switch. When in LFO mode, the LED shows the amount of modulation. In ENV mode, the LED shows the envelope state.

The ENV section has dedicated knobs for attack, hold and release. This allows you to customise the response and feel of the envelope follower depending on your audio source. For example, for rhythmic material, you might want to use very low attack, hold and release times for a “snappy” response. Alternatively, when emulating a wah-wah pedal used with guitar for example, longer attack and / or release times can produce very authentic results.

ATK varies the envelope follower attack time from 5-1000ms.

HLD varies the envelope follower hold time from 10-1000ms.

REL varies the envelope follower release time from 10-2000ms.

Please note that the envelope follower applies damping to its input to help achieve a smooth response and nice “feel”. Because of this, you may still notice some “ramping” up or down, even at very short attack or release times.

Below the IN jacks is an ENV sidechain input. When an audio signal is connected to this jack, the gain of the incoming audio at this input is used to drive the envelope follower. Please note the ENV input is designed to accept audio and is not a +/-5.0 CV jack, i.e. negative values will be treated as positive.

We hope you might consider enveloping your sound in filtered goodness with FILTERLOPE!

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