should offer supreme fidelity otherwise the engineer has little control or choice of
recorded “color” and little recourse to undo after the fact. Devices or circuits that
can easily be bypassed are usually better choices when “color” is a consideration
and this particularly is an area where one might consider comparing several such
devices. Beware that usually deviations from linearity carry at least as much long-
term penalty as initial appeal, and that one should always be listening critically
when recording and generally “playing it safe” when introducing effects that cannot
be removed.
1. Tsutomu Oohashi, Emi Nishina, Norie Kawai, Yoshitaka Fuwamoto, and Hishi
Imai. National
Institute of Multimedia Education, Tokyo. “High Frequency Sound Above the
Audible Range,Affects Brain Electric Activity and Sound Perception” Paper read at
91st. Convention of the A.E.S.October 1991. Section 7. (1), Conclusion.
2. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina.
“Temporal resolution of hearing probed by bandwidth restriction”, M. N. Kunchur,
Acta Acustica united with Acustica 94, 594–603 (2008) (http://www.physics.
sc.edu/kunchur/Acoustics-papers.htm)
3. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina.
Probing the temporal resolution and bandwidth of human hearing , M. N. Kunchur,
Proc. of Meetings on Acoustics (POMA) 2, 050006 (2008)
HOW THE 5051 COMPRESSOR WORKS
A part of the audio signal is rectified and smoothed to produce a suitable control
voltage for the VCA. which has to respond very quickly and have low distortion.
If the response is too fast, low frequency signals will themselves, be “gain
controlled”! If the response is too slow, the signal will overshoot and the first few
cycles will not get compressed. The speed and accuracy of the response, known as
the “attack”, and the time frame that gain remains under the initial control, known
as “release” or “recovery”, play a large part in the way a compressor sounds.
The 5051 uses very accurate, low noise, low distortion VCA having essentially no
“signature” of its own. This leaves the designer free to use amplifier and transformer
combinations that are well proven and produce the desired sonic quality.
All Rupert Neve Designs modules use input and output transformers and class-A
amplifiers to produce the musical “signature” for which they are known. These are
factors that enable the 5051 to work unobtrusively within the context of a very high
quality audio chain.
If the VCA control voltage is taken from the 5051 compressor input, (i.e. before
the VCA) the VCA “knows” right away that a gain change is required and there
is an almost immediate response. This is known, logically, as a “feed-forward”
compressor. If the VCA control voltage is taken from the 5051 compressor output,
(i.e. after the VCA) it cannot act immediately on the VCA because it has already
been modified by settings of the VCA and circuits through which it has passed. This
