Rupert Neve Designs Portico 5015 Mic Pre Compressor
The Rupert Neve Designs Portico 5015 is a fully analogue hardware unit, which combines independent transformer-coupled mic preamp and compressor-limiter sections, identical to those found on the 5012 and 5043 modules. The Portico 5015 features a highly transparent, low-noise mic-input for near-zero sonic colouration, a fantastic professional compressor/limiter, and a few additional functions such as the famous 'Silk' button.
- Fully analogue mic preamp and compressor/limiter
- Extremely low-noise and transparent pre-amp
- Silk button adds a subtle vintage effect to the sound
- Selectable Feed-Forward and Feed-Back compression modes
- Fully variable high-pass filter
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The microphone input is balanced but not floating, being a variant of an instrumentation amplifier 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.
In addition 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.
The Compressor Section
The 5015's compressor has fully variable threshold, ratio, attack, release and makeup gain with two selectable VCA modes that provide for exceptional control of any source material.
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 behaviour that reflects sonically on the final performance, and gives it a character or signature that can be musically attractive (or not)! The Portico 5015 makes use of a very accurate, low noise, low distortion V.C.A. having, essentially, no signature of its own.
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.
Feed Forward or Feed Back?
The Portico 5015 provides a choice of feed-forward or feed-back compression modes. The FF/FB Button allows the user to switch between these two modes.
The two compression characteristics are quite different. Almost all of Neve's earlier designs were 'Feed-Back'. These were more musical and sweeter than with 'Feed-Forward' designs, however the 'Feed-Forward' design provides greater accuracy.
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. 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 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 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 5015 module is a complete integral signal processor that delivers its specified performance independently.
Low Noise, Low Distortion Operation
Much care was given in designing the Portico 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 5015's sweet, whisper quiet performance.
Rupert Neve Designs Portico 5015 Specifications
Input Impedance: 10,000 Ohms +/- 20%
Main Output T.H.D: Better than 0.001%