RUPERT NEVE PORTICO 5024 4 Channel QUAD Microphone Preamplifier
Incorporating four channels of renowned preamplification, independent
silk controls, two channels of DI inputs, and an M-S Decoder into a 1U
enclosure, the 5024 is workhorse equipped to enhance the front end
performance of any digital or analogue recording system. Each channel
of the Portico 5024 is based around the custom transformers and class-A
circuitry found in the 5012.
In addition to 72 dB of gain, the 5024’s mic pres include
individually selectable phase, mute, phantom power, a selectable
frequency high pass filter, and the Silk circuit which yields the rich
warmth and presence of the renowned classic designs. Channels 1 & 2
of the 5024 feature a high-Z input designed for instrument level
sources. Channels 3 & 4 feature an M-S switch, which enables
Mid-Side decoding without the use of multiple console channels.
Microphone Input
The 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 permitting a full +25 dBu input signal to
be handled at unity gain without an input pad over the whole audio spectrum.
This combines the advantages of both an “Electronically Balanced” and true transformer input.
When the Phantom voltage is switched off, this input serves as a very high quality line input with an impedance of 10,000 ohms.
Low Noise, Low Distortion Operation
Much care was given in designing the 5012 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 5012′s sweet,
whisper quiet performance. For more information, go to Mr. Rupert Neve’s Design Notes
Why Transformers?
A complete discussion on transformers is out of place at this point
but a technical discussion will be posted at a later date. Here it is
helpful to review some of the essentials where it will be seen that a
design needs to be viewed as a whole, not simply from the point of view
of a single component.
The fine 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.
Incredibly 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.
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.
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 my
classic old favorite consoles 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.
In order 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 one of the reasons we use
transformers.
Silk
Much could 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 judgment.
M-S
The M-S button engages Mid-Side decoding on channels 3 & 4.
Channel 3 level controls the mid signal, and channel 4 level controls
the side signal.
Instrument Inputs
Balanced or unbalanced Hi-Z input for instruments using the Mic Pre's gain circuitry.
Level Meter
-30 dBu to +22 dBu
With reference to the output
Mute
Cuts of the output signal post metering and pre Buss Output. Be sure to mute the outputs before engaging phantom power.
High Pass Filter
The High pass filter is a valuable aid in any signal chain but
particularly so in a microphone preamplifier. Signals below 30 or 90 Hz
can be attenuated at 12dB / Octave, leaving the range above this
unaffected. This gets rid of building rumble, air handling motor hum
etc.
Phantom Power
Provides 48V phantom power to microphones
Phase Inverts
Flips the phase of an incoming source 180 degrees
