Ted Fletcher’s New Feed-forward Compressor Design

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Despite previously saying that tfpro will no longer be manufacturing 500 series modules, we are excited to announce that the new tfpro 588 module will be available on a limited basis to celebrate Ted Fletcher’s new feed-forward compressor design! Future availability of the 558 design will be through Ted’s ‘Alice’ company, as with tfpro’s other legacy 500 series modules. This new feed-forward design will also be available in a stereo version exclusively under Pye as a 19″ rackmount unit once completed.

Digital compressors and ‘plug-ins’ excel as volume limiters but often fail to match the effects possible on analogue devices.

Analogue compressors are particularly good at controlling volume levels and work as useful tools for individual instruments in a recording.

An ongoing problem with all types of compressor whether new or old, is to get a fast smooth attack without compression overshoot, that is, when there is an audible ‘ripple’ immediately following a sudden transient. It is an effect that even shows itself on BBC TV in some classical music feeds.

Analogue compressors are generally ‘feedback’ types, they operate by sensing audio levels at their output and then applying correction to a gain reduction stage near the input. This arrangement works well, but it is liable to suffer from ‘overshoot’ where when faster attack times are demanded, the control system fails to react efficiently causing momentary peak overloads and dipping effects.

Digital compressors are normally ‘feed-forward’ types where the incoming signal is sensed and used to control the gain of the audio path. Most are modelled on historic analogue compressors with varying accuracy.

The 588 operates as a ‘feed forward’ compressor sensing the incoming signal and immediately sending a control signal to a gain-setting circuit near the output. The control signal circuitry sets the momentary compression ratio and the audio signal is instantly controlled by the control signal and the switchable attack time.

The ‘sound’ of this compressor is consistently superior because of tonal effects created during the compression process. A digital compressor handles audio totally symmetrically; any minor distortion produces symmetrical (odd order) harmonics. These extremely small errors influence the sound in an unnatural way, they produce a slightly flat clinical effect.

The 588 compressor operates more naturally; the harmonics generated by the compression process are asymmetric (even order) similar to effects common in nature and pleasant to the ear.

This sounds technical and complicated but the effect is clear and simple; The 588 brings audio into focus; it is like having a variable contrast control, particularly effective for clarity and for bringing a solo voice forward and more present in the mix.

The first 10 units of the tfpro 588 are available to order now at an introductory price of £220, before increasing to £315. Read more and order your tfpro 588 now!

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