Rupert Neve Portico 5043 - Compressor / Limiter Duo - Manual (Page 3)

INTRODUCTION
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In a traditional console large, bi-polar regulated supplies were used, necessarily having a shared
common 0 "ground" wire. Crosstalk between modules resulted, often accompanied by R.F.
interference due to the unbalanced loop "antennas" that were inevitably present. This interference,
in some cases, could actually be heard, but even at low levels below audibility there was a potential
intermodulation with the desired signal. Of course this represented both a quantitative and
subjective intrusion affecting sound quality.
One of the advantages of the Portico TM method of feeding equipment is that external power units
will work from almost any of the very wide range of mains supply voltages and frequencies that are
found world-wide. While many different types of mains power wall sockets are found in different
countries, Portico TM 5043 module power units leave the factory with standard US plugs. If
required, any suitable connecting cord may be substituted.
Avoid using a mains power outlet that is on the same circuit as air conditioning of other equipment
that regularly switches on and off. Unplug your Portico TM power units during a thunder storm or if
it will be unused for a long period.
Portico TM modules can alternatively be powered from a 12 volt battery, in which case the supplied
AC power unit is not needed. When using a 12 volt battery, choose one that has enough capacity to
power your Portico TM 5043 - or your complete assembly of Portico TM modules - for the expected
duration of your session.
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.