In real life acoustic situations the human voice is cable of producing sounds
that cover a wide dynamic range - from a gentle whisper to an ear-piercing scream.
The same can be said about electric and acoustic instruments. If these dynamics are
recorded linearly there is a tendency for softer sounds to drop below the threshold of
perception, particularly if the sound playback systems (amps and speakers) are not
aligned to real life volume, but are instead, adjusted for listening pleasure.
This creates a need to reduce the dynamic range of a sound so that it can fit into the
limited range of a playback or recording system.
This is where valves and audio compression enter the picture. The Thorax uses
a transformer coupled valve preamp to subtly act on the signal and reduce dynamic
range. The Class A circuitry running on High Voltage rails means that internally,
the signals can have a wide voltage swing that permits all the goodness of the valve
and transformer to come to the fore, shaping the signals naturally.
This preamp also features a passive EQ designed to accentuate the positive
aspects of the textures and harmonics generated in the valve. The frequencies
chosen are the ones that resonate best within the architecture of the circuit.
The preamp/EQ is followed by the optical compressor, there the user can
further interact with the signal process and apply audio compression as needed. The
dynamic range of the output can then be adjusted so that vocals, for example, sit
consistently and clearly present in a mix. The quieter moments won’t drop out and the
louder moments won’t distort or overload. Naturally this also applies to all
instrumentation.
For recording signals direct from electric instruments such as synthesizer,
electric guitars, Bass etc. the Thorax is also well suited as a valve D.I with the Direct
Input on the front panel. This is a High Impedance direct feed to the grid of the valve
and when levels are optimised will yied an excellent signal to noise ratio that is
perfectly suited to digital recording.
The running of pre-recorded tracks is another process the Thorax has been
designed for, signals can be fed into the Thorax and organically sculptured to suit.
Signals can be injected in up to three different ways by using the preamp XLR input,
preamp direct input or external line input for the compressor.
For creative applications the Compressor section of the Thorax has been
designed with added features such as compression mix, as well as, two modes of
compression based on where detection takes place - feedforward or feedback.
All these features, coupled with a well thought out and streamlined circuit,
is what makes the Sebatron Thorax a highly desirable and practical
recording tool solidly built to last a lifetime.
1. Introduction
