The Klavis Tweakers is a 3HP Eurorack module for shaping control voltages. It has two channels, each with gain, offset, polarity switching and mute. It suits patches where a modulation source needs scaling, shifting or inverting before it reaches a CV input that has no attenuator or offset control of its own.
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Two independent channels, each with an input, an output, a gain pot, a bipolar offset pot and a three-position switch
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Gain from zero to about x2.1, so it can amplify weak signals as well as attenuate them
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Bipolar offset that is zero at centre and is not affected by the polarity switch
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Inverted / off / normal switch per channel, for flipping or muting a signal on the fly
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Normalled input and output that turn the module into a splitter or a two-channel mixer without extra cables
The normalling is what makes the module more than two plain attenuverters. With nothing patched into input B, input A feeds both channels, so one source can be processed two ways without a multiple. With nothing patched into output A, output B carries the sum of both channels.
Using both paths at once gives a useful performance trick. Channel A holds a base setting, such as a transpose voltage. Flipping the switch on channel B then adds or subtracts a prepared variation without muting A. The same approach works for switching between preset pitch offsets during a live set.
The Tweakers is DC-coupled and runs from DC to beyond audio rate, so it also works on audio. The manual describes using it as a simple audio mixer. It also describes overdriving waveforms on purpose to clip them and change their harmonics, for example turning a triangle or saw into a half-trapezoid, then re-centring the result with the second channel. A slow modulation can make that waveshaping move over time.
The offset can also convert a unipolar signal to bipolar and back. The module comes with either a silver or a black aluminium panel.