Rupert Neve Portico 5043 - Compressor / Limiter Duo - Manual (Page 8)

FEATURES
7
THE 5043 LINE AMPLIFIER
The Portico™ 5043 consists of two identical Line Driving amplifiers having transformer balanced
inputs and outputs. The sonic quality of these amplifiers is such that, by providing galvanic
isolation, simple single-sided circuit topology, and freedom from grounding problems, they are
capable of enhancing the sonic quality of many signal sources, especially those of digital origin.
The sonic "signature" is one of extreme purity and the image is consistent with that of Mr. Rupert
Neve's original designs of 35 - 40 years ago. More detailed discussion on the sonic image and the
way in which an analog designer's approach can sweeten and "warm" some of the cold, storage and
editing processes may be found on www.rupertneve.com.
PRINCIPAL FEATURES
There are two identical channels, A and B, in the Portico™ 5043 Compressor- Limiter. The
controls of each channel can be adjusted independently. A "LINK" Push-Button is provided on each
channel that, when operated, connects the DC control lines together and enables the gains to work
together.
COMPRESSION
For signals below the "threshold" level that has been set, a compressor provides a linear path
allowing signals to be amplified without the gain being adjusted in any way. When signals exceed
the "threshold" level, the gain is reduced in a controlled manner that depends on the Ratio setting.
RATIO
Range 1:1 to LIMIT (i.e. 40:1)
Above a given THRESHOLD signals are reduced by an adjustable amount ranging from 1:1,
(which is linear, or no reduction at all), to more than 40:1 which is a very high ratio, equivalent to
that of a limiter.
RATIO is sometimes referred to as "Slope" because when depicted on a graph, the "slope" of the
graph representing Output versus Input, is what changes. RATIO is measured in dB (Decibels).
The 40:1 figure mentioned above, means that a change in input signal level of 40 dB only results in
1 dB change in output level!
RATIO and THRESHOLD are closely inter-dependent. If a RATIO as high as 40:1 has been set,
and if the THRESHOLD is set at 0 dBu, then even when a massive signal of +40 dBu (unlikely!) is
presented to the input, the output signal will only be +1 dBu. RATIOS as high as this would
normally be set somewhere above 0 dBu - say at +14 dBu, in order to prevent the output signal
level exceeding just over +14 dBu to protect, for example, a digital recorder. Similarly, if a RATIO
of 5:1 has been set, an input signal which is 10dB above THRESHOLD will only rise by 2dB
above that THRESHOLD at the output.