A simple musical accessory that creates smooth compression and limiting to squash the dynamic range of a signal whilst enhancing the percussive and harmonic qualities of it.

It uses a simple analogue circuit for the ultimate in sound quality and transparency of tone.

The gain may be selected (common to both effect and bypass modes) either at Unity (0dB) gain, -3dB attenuation or +3dB boost, depending on the position of the 'Axematch' 3-position toggle switch. This feature allows matching of the disparate levels found between the three most common guitar pickup types, namely large single coils such as the P90 (preferred switch position: centre), twin coil 'Humbucking' (preferred switch position to the left/attenuate -3dB) and standard single coil types such as on most classic Fender® guitars (preferred switch position to the right/boost +3dB).

Subsequently connected devices will then require less gain adjustment. A slide-switch inside the unit allows for parallel mix mode SB or "Straight Blend", whereby the compressed signal is added in-phase with the dry input signal and gives a relative boost. The "Z" mode/position makes the output "Balance" control go to zero signal when fully anticlockwise like on a conventional compressor. This internal slide switch is situated beneath the bottom right-hand edge of the printed circuit board, and is factory set for "Z" mode. This pedal is designed to be positioned near or preferably at the very start of an effects chain: immediately after the (good quality!?) cable coming from a guitar.

This makes it an ideal low-noise line driver and master gain-setting device, for getting the best results from your FX rig. It also performs usefully with the above features as a handy D.I. box for studio applications, despite having an unbalanced output. Another application, for example would be to connect the output of a close-positioned microphone (from a guitar amp cab) straight into the input and feed the OTC-201's output direct to a PA or recording console. The 3-position "Axematch" switch also allows for optimum headroom adjustment when used in a mixing console insert do try using it in this way: the OTC-201 sounds good with all kinds of recorded instruments and on (mono/bussed) programme material.

Why its different…

This design uses optical modulation to allow for quiet, low-noise operation and a natural envelope characteristic. The attack of a guitars note is allowed to pass through relatively unchanged, owing to a fairly slow attack time. The release time is dependent upon programme content (i.e. what kind of signal level has passed before) so is best described as medium with auto/variable release. In other words, it responds faster to higher signal levels than to lower ones. The circuit is designed to emphasise gently the treble frequencies on the attack of notes and for the bandwidth to narrow slightly as the notes decay, also conveniently reducing noise. This is dependant upon the "Sustain" control setting which narrows the bandwidth more at the higher settings. When "Sustain" is set towards or near zero there is little or no treble emphasis, as well as far less compression.