Rupert Neve Shelford 5051 Inductor EQ / Compressor - Manual (Page 5)

5
THE NEED FOR DYNAMIC CONTROL OF SOUND LEVELS
The dynamic range of sounds we hear around us in normal life greatly exceeds the capability of our
best recording and processing equipment - but even if this were not so, the scale of dynamic range
must be accommodated to the venue in which it is to be reproduced. For example, actual volume
levels of the dance hall would be deafening in a students bedroom. In the same way, late night
listening in a quiet living room demands careful adjustment of dynamic range. In the constantly
changing background noise of a car, drama dialog does not work without constant attention to the
level control. In the field of communications, it is often necessary to ensure that the best possible
signal-to-noise ratio is obtained, in the interest of intelligibility, within the limited performance of,
say, a reporter’s recording device.
Digital recorders are unforgiving when overloaded. Overload can be avoided with careful use of
high ratio compression - on the verge of limiting - with careful choice of time constants. A
recording that still sounds “loud” can be produced without non-musical harmonic distortion.
A compressor-limiter is one of the most powerful, yet subjective items in the sound engineer’s
armory. Compression should never be obvious to the listener and this needs intuitive and effective
controls on the part of the designer together with considerable skill on the part of the sound
engineer.
A NOTE ON DISTORTION
The human hearing system is a remarkably complex mechanism and we seem to be learning more
details about its workings all the time. For example, Oohashi demonstrated that arbitrarily filtering out
ultrasonic information that is generally considered above our hearing range had a measurable effect on
listener’s electroencephalo-grams. Kunchur describes several demonstrations that have shown that our
hearing is capable of approximately twice the timing resolution than a limit of 20 kHz might imply
(F=1/T or T=1/F). His peer reviewed papers demonstrated that we can hear timing resolution at
approximately with 5 microsecond resolution (20 kHz implies a 9 microsecond temporal resolution,
5051: Block Diagram
Compressor S/C
Thresh Attack
Release Ratio
VCA
HPF S/C Send/Return
Inpu t
Tran sformer
Ou tput
Tran sformer
Meter
Ou tput
Redu ction
Meter
EQ In
HPF In
G ain
Compressor In
EQ Pre/Post
FF/FB
Mid Band Shelves
HPF
IP 1
IP 2
Input Select
Link