Rupert Neve Portico II - Channel - Manual (Page 8)

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of a de-esser that pulls down the volume of the whole signal if it senses an “ess”. And it should be noted
that the built-in Channel Strip De-Esser acts in a different way and only reduces the narrow area of
frequencies that the High Mid EQ is set for. You would be correct if you thought that both of these types
of de-essing can be used independently for a “difficult” track.
A few notes about these jacks. They are unbalanced and ideally best suited to be used with unbalanced
equipment. However most balanced EQ’s will work fine interfaced to these jacks. The simple symptom
of a balanced / unbalanced mismatch is that the “compression meter” will indicate a significant change
of compression depth (like zero) when the EQ is set flat. Keep in mind that nobody hears this signal path
so that any old nasty sounding EQ you tossed in a closet years ago might be perfectly suited for a side
chain insert task.
THE LINK CONNECTORS
These jacks are used when one is lucky enough to have two (or more) Portico Channels and would like
to use them with a stereo source and specifically when one wants to have the two compressors follow
and match each other. This helps to preserve the stereo image because both the compressor for the left
and the compressor for the right will then raise and lower gain the same amount.
MICROPHONE PREAMPLIFIER DESIGN NOTES
In former years, before the introduction of solid state amplifiers, transformers were necessary to
step up to the very high input impedance of tubes, and to provide a balanced input for the
microphone line. An input impedance of 1,000 or 1,200 ohms became established for microphones
having a source impedance of 150 or 200 ohms, with connection being made on a twisted twin
screened cable (This type of cable, while excellent for low impedance work, has high capacitance
between its conductors and between each conductor and screen. Resultant high frequency losses
are excessive with piezo pickups and may cause resonances with magnetic pickups.) Thus
microphones were not heavily loaded. Condenser microphones worked off high voltage supplies
(300V!) on the studio floor which polarized the diaphragms and powered a built-in pre-amplifier.
More and more microphones were needed as “Pop” music gained ground and this led to the popular
and efficient method of 48-volt “Phantom” powering that was built into the multi-channel recording
Console – in place of numerous bulky supplies littering the studio, a miniature pre-amplifier now
being fitted inside the microphone casing.
The 48-volt supply was fed to the microphone through balancing resistors so it was impossible for
this voltage to actually reach the microphone, resulting in low polarizing volts and virtual
starvation of the little pre-amp inside the microphone. Nevertheless amazingly good microphones
were designed and made, becoming the familiar product we use today. If a low value resistive load
is connected to the output of an amplifier, that amplifier has to produce power in order to maintain a
voltage across that load. Obviously if we want more voltage (output from the microphone) we need to
provide a larger supply for the amplifier or settle for a lighter load. A microphone is a voltage generator,
not a power amplifier. Most microphones give their most accurate performance when they are not
loaded by the input impedance of a traditional preamplifier. If the microphone uses an electronic circuit
(transformerless) output, a low value of load impedance can possibly stress the little microphone pre-
amplifier, causing slew rate and compression at high levels.
On the other hand, a high value of load impedance allows the microphone to “breathe” and give of
its best, this being particularly advantageous with very high level percussive sounds. If the microphone
has an inductive source (such as would be the case if it has a transformer output) a low value of load