Rupert Neve Designs Portico 5015 Product Features
independent transformer-coupled mic preamp and compressor-limiter sections
identical to those found in the 5012 and 5043 modules, the fully analogue
Portico 5015 combines the outstanding sound quality expected from a Rupert Neve
design with the total flexibility required by modern recording studios.
Available in both Vertical and horizontal configurations, when used with the
5033 five band EQ it is possible to create a Portico channel strip with
preamplification, dynamics processing and equalization. As an additional
routing option, the mic pre output may be routed directly to the compressor
section without patching by pressing the To Compressor switch.
microphone input is balanced but not floating, being a variant of an
instrumentation amplifer using a Transformer-Like-Amplifier (T.L.A.)
configuration with a toroidal Common Mode Rejection Low Pass Filter that excludes
frequencies above 150 kHz. The T.L.A. is followed by an actual input
transformer designed by Mr. Neve that permits a full +25 dBu input signal to be
handled at unity gain without an input pad over the whole audio spectrum. This
innovative solution combines the advantages of both an Electronically
Balanced and true transformer input.
to the 72 dB of gain, the 5015 mic pre includes individually selectable phase,
mute, phantom power, a swept high pass filter from 20-250 Hz, and the Silk circuit
which yields the rich warmth and presence of the renowned classic designs.
compressor has fully variable threshold, ratio, attack, release and makeup gain
with two selectable VCA modes that provide for exceptional control of any
In order to
control gain, a V.C.A. or Voltage Controlled Amplifier (or Attenuator) is used.
There are many types of V.C. including the use of tubes, discrete and
integrated solid state circuits and naturally non-linear devices, each one
having its characteristic behavior that reflects sonically on the final
performance, and gives it a character or signature that can be musically
attractive or not! The Portico 5043 makes use of a very accurate, low noise,
low distortion V.C.A. having, essentially, no signature of its own.
A part of
the audio signal is rectified and smoothed to produce a suitable control
voltage for the V.C.A. 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 and plays a large part in the
way a compressor sounds.
modules use input and output transformers and, almost entirely discrete
component amplifiers. In fact the Line amplifiers on their own, inserted into
the signal chain, are capable of enhancing the sonic quality of many signal
sources, especially those of digital origin. These are some of the factors that
enable, the Portico 5043, to work so unobtrusively within the context of a very
high quality audio chain.
Forward or Feed Back?
5043 provides a choice of feed-forward or feed-back compression modes. The FB
Button allows the user to switch between the two modes.
V.C.A. Control voltage is taken from the 5043 input, (i.e. before the V.C.A.)
the V.C.A. knows right away that a gain change is required and there is almost
immediate response. This is known, logically, as a Feed-Forward compressor.
V.C.A. Control voltage is taken from the 5043 output, (i.e. after the V.C.A.)
it cannot act immediately on the V.C.A. because it has already been modified by
settings of the V.C.A. and circuits through which it has passed. This is known
as a Feed-Back compressor. The two compression characteristics are quite
different; there is more Overshoot and both the attack and recovery ramps are
changed, providing the user with powerful choices. Almost all of Neves earlier
designs were Feed-Back. They were more musical and sweeter than with
Feed-Forward designs; however the Feed-Forward design provides greater
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.
Threshold are closely inter-dependent. If a RATIO as high as 40:1 has been set,
then if the THRESHOLD is set at 0 dBu, 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.
control covers the Range from below -30dB to +22dBu. When THRESHOLD set at a
low level, with a fairly high RATIO the amount of gain reduction will be
considerable and it may be necessary to use some GAIN after the compressor to
restore the apparent signal level. ATTACK TIME
time is the time taken for the compression circuits to start compressing. A
long ATTACK time allows short duration peaks to escape and go through
uncompressed. This may cause overload on subsequent digital circuits. A very
short attack time sounds un-natural and robs the signal of life by removing
transients. Some transients are extremely fast and have little effect on the
sound quality. Setting a long attack time often means that almost no gain
reduction occurs because the transient is history (!) before compression has
had time to operate. However, even the fastest circuits take time to operate
which means that there is always some Overshoot. Small amounts of Overshoot
are musically desirable - there are exceptions, of course.
right values of RELEASE and ATTACK is what compression is all about! Once the
principles are understood a Compressor-Limiter such as the 5043 provides a
powerful tool that actually appears to enhance the dynamic range of a recording
and so provide greater musical enjoyment.
above explain how the 5043 handles signals of constant amplitude such as pure
tones. Real program signals, however, are continually changing in level. The
way in which a compressor deals with actual program material depends upon the
magnitude and duration of peaks in the program level. If the RELEASE TIME is
set to be very short, a short duration signal will be compressed but the gain
will return to normal very quickly, giving a fluctuating and un-natural sound
known as Pumping when the background, or other signals, are forced up and
down. The gain will also tend to follow the wave form of low frequency signals.
RELEASE TIME should be set long enough for the gain to remain reasonably
constant between each bass note or between speech syllables.
subtleties of circuit design relating to sonic performance are gradually
becoming more clearly understood. For example, research has shown conclusively
that frequencies above 20 kHz affect the way in which humans perceive sound
quality. But, long before scientific evidence emerged a substantial body of
musicians and engineers knew that equipment with apparently the same technical
measurements could sound very different.
small amounts of musically dissonant odd harmonics have a disastrous effect on
the sound quality. Extraneous noise or interference that finds its way into a
signal path seriously impairs performance of the whole chain. Since many
control rooms make use of outboard gear that is not well protected from
external signals. Poor grounding of such equipment can be a serious problem.
Electronically balanced circuits much used in modern equipment, can give very
good measurements on the test bench but they do not provide adequate rejection
of the stray fields found in every working environment.
these issues, input and output circuits must be freed from ground dependence so
that only the wanted signal enters and leaves the processing path.
Transformers are the ideal solution. The sweet and silky sound of Mr. Neves
classic designs was achieved with big transistors and large high quality
transformers. Rupert Neve Designs Portico modules achieve similar quality today
without the bulk or the cost.
that modules can work together as would be expected (i.e. in a proprietary
console configuration) without producing hum, R.F. interference, or other
interactions, the connecting interfaces, grounding, levels and impedances must
receive careful attention. Each Portico module is a complete integral signal
processor that delivers its specified performance independently. This is why we
LOW DISTORTION OPERATION
was given in designing the 5015 to produce as little noise and non-harmonic
distortion as possible. Carefully implemented signal paths and Class A
operation are a large part of the 5015s sweet, whisper quiet performance.
be written about this feature, suffice to say, that it gives a subtle option to
enhance sound quality in the direction of vintage modules. The Silk button
reduces negative feedback and adjusts the frequency spectrum to provide a very
sweet and musical performance. We suggest you try it and make your own
-30 dBu to
+22 dBu With reference to the output
Cuts of the
output signal post metering. Be sure to mute the outputs before engaging
pass filter is a valuable aid in any signal chain but particularly so in a
microphone preamplifier. Signals between 20 and 250 Hz can be attenuated,
leaving the range above this unaffected. This gets rid of building rumble, air
handling motor hum etc.
48V phantom power to microphones
phase of an incoming source 180 degrees
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 that has been set.
provided is from -6dB to +20 dB. ?As already noted, when compression has taken
place, it may be necessary to increase the overall gain to restore the apparent
1:1 to LIMIT (i.e. 40:1)
-30dBu to +20dBU
20 mS to 75 mS.
RELEASE time is 100 mS to 2.5 Seconds.
LINK Push-Button is engaged on two channels of Portico compressors connected
via the link inputs set to approximately the same values, gain reduction on
both channels will be the same to preserve Stereo balance and center imaging.
LINK Push-Button is engaged and the link input is connected to another Portico
series compressor with LINK engaged, the signal passing through one the
compressors, may be used to control the amplitude of the Portico compressor its
LED METER is provided that show GAIN REDUCTION in the compressor.
is calibrated in dB covering the range -1 to -22 dBu, reading from right to