Rupert Neve Designs Portico 5024 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 Rupert Neve Designs Portico 5024 is a 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 best-selling 5012.

In addition to 72dB of gain, the Rupert Neve Designs Portico 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, 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.

When the Phantom voltage is switched off, this input serves as a very high quality line input with an impedance of 10K Ohms.

Low Noise, Low Distortion Operation

Much care was given in designing the 5024 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 5024′s sweet, whisper-quiet performance.

All Portico 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 5024 to work so unobtrusively within the context of a very high quality audio chain.

Why Transformers?

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 20kHz 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 can 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.

To correct 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. Neve’s 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.

In order for modules to 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 use transformers.

Features:

• 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.

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Frequency Response:

• Main Output, no load,
• –3 dB @ 2 Hz
• –3 dB @ 160 kHz

Noise:

• Measured at Main Output, unweighted, 22Hz-22kHz,
• Terminated 150 Ohms.
• With gain at unity better than –92 dBu
• With gain at 66 dB better than –56 dBu
• Equivalent Input Noise better than –123 dBu

Gain:

• Unity to +66dB in 6 dB steps,
• Trim continuously adjustable from –6dB to +6dB

Line Input:

• Trim continuously adjustable from –6dB to +6dB

Maximum Output Level:

• Maximum output from 20 Hz to 40 kHz is +25 dBu

Phantom Power:

• 48 Volts DC +/- 1%

Total Harmonic Distortion and Noise:

• @ 1kHz, +20 dBu output: Better than 0.002%
• As above, Silk Engaged: Better than 0.2% Second Harmonic
• @ 20Hz, +20 dBu out Better than 0.004%
• @ 20Hz, +20 dBu out Better than 0.020%
• IM Distortion: Better than 0.002%

• Slew rate Better than 4 V/uS
• High Pass Filter:
• Frequency: Selectable either 30Hz or 90Hz
• Slope: 12 dB/Octave Bessel