- Effect/Bypass (2x)
- When in bypass mode audio in is connected directly to audio out.
- Envelope Source (2x)
- Selects which signal drives the envelope follower circuit.
In INT. position the sound being treated is used as the control signal for the envelope follower.
In EXT. position the external control input becomes the envelope follower control signal.
- Env/Gate (2x)
- In Env mode the envelope follower acts as its name implies, precisely following the amplitude of the control signal and producing a rapidly varying control signal which can be used to sweep the Cut-Off frequency of the Filter and/or volume level of the VCA. In Gate mode the envelope follower is either full on or completely off, depending on whether a controlling signal is above or below the gate threshold as set by the sensitivity control.
When MIDI is implemented this switch also routes MIDI note on/off information to either gate or LFO re-trigger.
- Sensitivity (2x)
- In Env mode this sets the optimum drive level for the envelope follower circuit. Too low and the LED only glows faintly, too high and the LED is driven hard on. The optimum setting is when the LED peaks in brightness at the loudest points of the control signal.
In Gate mode the sensitivity control sets the threshold level at which the gate operates.
- Attack (2x)
- This adds an attack time (fade-in) at the front of the envelope. When set to zero (fully anti-clockwise) it has no effect on the envelope contour - fully clockwise it gives up to 2 seconds of fade-in.
- Release (2x)
- This adds a variable release â€œtailâ€ to the envelope. Even after the control input signal has died away up to 5 seconds of fade-out may be added by this control. Setting this control to small amounts can be useful for smoothing out rapidly changing envelopes when in Env mode.
- Rate control (of LFO) (2x)
- This changes the sweep rate of the low frequency oscillator, from about one cycle every ten seconds to 100 cycles per second. Note that when the Link switch is on only the rate control of Channel 1 has any effect as it is being used to control both channels (LFO 2 is switched out when Link is in).
- Waveform (2x)
- Selects between the four available low frequency oscillator waveforms - Triangle, Square, Ramp up and Ramp down.
- LFO Depth (2x)
- Determines the amount of LFO sweep sent to the filter and/or voltage controlled amplifier.
- VCA/Both/VCF (2x)
- Selects whether the output of the LFO sweeps the voltage-contolled amplifier, the Voltage-controlled filter, or both simultaneously.
- Envelope Sweep (2x)
- Determines the amount of filter frequency sweep (up or down) being sent to the voltage controlled filter from the envelope follower.
- Cut-Off Frequency (2x)
- This sets the centre roll-off frequency of the voltage-controlled filter.
- Resonance (2x)
- Sets the Resonance (or Q) of the VCF. High values produce self-oscillation.
- VCA In/Out (2x)
- Selects whether the final output goes through the voltage-controlled amplifier or is taken from the VCF output.
- Link Normal/Invert
- LFO 1 can be sent to channel 2 for stereo panning/cross-modulation effects. The Normal/Invert switch inverts the output of LF0 1 that is being sent to channel 2. This is particularly useful for stereo effects.
- Link In/Out
- When in, LFO 1 is sent to both channels (for stereo effects), when out, LFO 1 affects channel one, and LFO 2 affects channel two.
After more years than I would care to mention of being a recording engineer, I have come to a definite conclusion. True stereo filtering seems to alter spatial perceptions in a bizarre and unexpected way. I first came to this conclusion many years ago whilst slaving away on reggae sessions trying to create the ultimate dub.
After hours of total self gratification - fiddling with the EQ sweeps of my mixing desk, I sheepishly turned round to see whether the band had lost the will to live or at the very least abandoned all hope of leaving the studio with a finished master.
To my utter astonishment and ego enhancement I was presented with several pairs of feet pointing towards the heavens with quivering smiles of ecstacy plastered across their lips. It wasnÂ't their music any more - it had turned into something strange and indescribable - but somehow it didnÂ't seem to matter.
Several years later I was re-creating this effect on the majority of my sessions and was beginning to feel slightly miffed at the dull, nagging ache I was developing in my back from bending over the desk like a bloody contortionist to get to all those darned EQ pots.
Â“Hark!!Â” I thought to myself Â“What if all these knobs were in one unit - what if all these wonderful sounds could be produced from one box - what if Pamela Anderson really was my girlfriend - what if one piece of outboard could produce stereo filtering, frequency dependent panning, gating, LFO blah blah blah blah...”
The Mutator was born.