Rupert Neve Designs Portico

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Duo Mic Preamp & 5-band Equaliser

Published in SOS April 2007
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Reviews : Preamp

Photos: Mike Cameron

Rupert Neve is a name that virtually everyone involved in professional audio will know, and the legendary classic Neve designs are as revered today as they ever were. However, it would be wrong to assume that the 'Neve' sound is restricted only to vintage designs — Mr Neve continues to develop and refine his analogue engineering, and the latest products from his drawing table are available in the form of the Portico range of modular signal processors from Rupert Neve Designs, his independent business incarnation.

The Portico product range currently includes seven units, with three different mic preamps, a stereo sound-stage controller, a tape emulator and line driver, a dynamics processor and a 5-band EQ. As standard, these units are all 1U-high, half rack-width horizontal modules — although they can optionally be converted for a vertical mounting format — with cases that are constructed from heavy folded steel to minimise electromagnetic interference.

Portico 5012

The 5012 is a dual microphone preamplifier with two independent channels, each equipped with the standard facilities, plus a variable high-pass filter. The rear panel features XLRs for the two mic inputs and main line outputs, plus two pairs of TRS quarter-inch sockets for buss linking. There are separate linking busses for each mic channel (labelled A and B), and the two sockets for each allow the buss signal from another unit to be patched in and then the combined output passed on to another unit. In essence, this creates a stereo mix buss which is intended to terminate at a dedicated buss amp-cum-monitoring module, such as the 5014 MS-stereo buss mix and stereo field module. Since the interface is unbalanced and high impedance, and operates at a slightly depressed nominal level compared to the main output, these buss outputs cannot be used easily for any other purpose.

There is also a coaxial DC power inlet socket and adjacent power on-off button (with a supplied but optional clamp to retain the cable). The unit contains two DC-DC converters which regenerate the required ±17.5V internal rails plus a +48V phantom supply, and these can happily accept any DC source between 9V and 18V. The supplied in-line universal mains unit puts out 15V at up to three amps, such a hefty supply being required because the 5012 dissipates about 35 Watts.

The front panel is clean and simple, with the two channel sections being arranged side by side. Each channel is provided with push buttons to select phantom power, polarity inversion, main output mute and high-pass filter, and to activate the mix-buss feed. These neat buttons look black when switched out, but illuminate when activated, so the current status is always obvious.

The rear panel of the 5012 features XLRs for the two mic inputs and main line outputs, plus two pairs of TRS quarter-inch sockets for buss linking. The rear panel of the 5012 features XLRs for the two mic inputs and main line outputs, plus two pairs of TRS quarter-inch sockets for buss linking. The rear panel of the 5012 features XLRs for the two mic inputs and main line outputs, plus two pairs of TRS quarter-inch sockets for buss linking.

The main gain control is a 12-position rotary switch with 6dB between each stop, spanning 0-66dB in total. In addition, a continuously variable trim control provides another ±6dB of gain. The second order (12dB/octave) high-pass filter can be adjusted between 20 and 250Hz, or bypassed completely, and the bar graph meter spans -30 to +22dBu with eight LEDs.

The only shared control is a button labelled 'Silk', which alters the circuitry to use less negative feedback and tweaks the tonality slightly to give a slightly tailored sound character. Reducing the level of feedback makes the harmonic distortion figure rise slightly at 1kHz, from 0.001 percent to 0.002 percent, but at 20Hz it rises much more, from 0.002 percent to 0.2 percent — with predominantly second-harmonic distortion. It is this that gives it a slightly richer and more 'vintage' character, along with a slightly different dynamic response.

The circuitry is built almost entirely using conventional-sized components, with the old familiar NE5534 op-amps doing the bulk of the work, supplemented with separate transistors in appropriate places. Rupert Neve's designs traditionally employed single-sided class-A topologies, and it is hard to square that approach with these Portico circuit boards covered in op-amps. The secret missing ingredient is that he uses a circuit technique with the 5534 op-amps which offsets the DC point of their output stages, so that for signals below about 0dBu they are effectively running in a single-sided class-A mode. This removes crossover distortion artifacts completely and is a significant contributor to the sound of this preamp.

The entire design approach is equally unorthodox. Unusually, although the input does have a transformer, this is not the first thing the mic input signal sees. Instead, after a common-mode torroid ensures that nothing above 150kHz can get into the preamp, the signal is handled by Rupert Neve's own 'transformer-like amplifier' (TLA) configuration. This is a variation on the familiar instrumentation amplifier theme, and presents the input with an unusually high input impedance — 10k(omega), in fact — which minimises the microphone loading and is claimed to improve 'transparency.'

The input transformer follows this TLA stage, and overall, the input stage can tolerate a massive +26dBu without needing a pad. Given the relatively high input impedance, the mic input is quite happy serving as a line input — provided phantom power is switched off, of course.

A second transformer has two secondaries, with one feeding the main output and the second feeding the buss output, meter, and output stage negative feedback. The main output is fully floating (ground free), to minimise the risk of ground loops and radio-frequency interference. The maximum output level is +25dBu, which is more than enough for even the hottest of A-D converters! The signal bandwidth is flat out to a -3dB point at 160kHz, and is only -0.2dB down at 10Hz. Mr Neve takes care to maintain the LF phase integrity, and he claims all his designs maintain phase below five degrees down to 10Hz. At unity gain, the unweighted noise is a very impressive -100dBu, helped, no doubt, by the fact that the mains power supply is external.

The 5088 Analogue Mixing Console Rupert Neve is, of course, best known for his analogue consoles and it is fantastic that even at 81 years of age he is still contributing to the art of the analogue console. The new 5088, currently in pre-production, essentially sums up his life's work of maximising the technical and aesthetic capability of analogue audio circuitry. The first production console is expected to be delivered in May this year, and will go to Sonic Distribution's new demo studio in the UK. The smallest desk configuration has 16 input channels, feeding eight groups and a stereo master, and the basic console is designed as a line-level-only device, with 'buss' and 'tape' inputs on each channel. There is no EQ or dynamics processing at all, but there are eight aux sends per channel, and every channel also has a direct output. Additional 16-channel input sections can be added to increase the console capacity, and it is claimed that there is no upper limit to the potential channel count! The basic 16:8:2 console is expected to cost around $30,000, with a 32-channel desk costing about $43,000. In addition to the optional input expanders, there are also optional meter bridges, with moving coil VU or LED bar-graph meters. For those who require mic inputs or signal processing, a penthouse can be attached to accommodate any of the Portico modules (in vertical format). The console channel spacing is designed specifically to make this arrangement practical. Optional 'Flying Fader II' fader automation can also be included if required. The desk — the first Rupert Neve has designed from scratch since the Focusrite consoles — has several interesting features. Perhaps the most significant on a technical level is that the 5088 has 10dB more headroom than any previous design, while maintaining the very wide bandwidth with which Rupert Neve's consoles have become associated. Every input and output on the desk is transformer coupled, and the entire circuitry is all discrete single-sided class-A. From an operational perspective, the 5088 is very straightforward. Large illuminated solo and cut buttons sit above the fader scribble strip, along with a bypassable stereo pan control. Above this the eight aux sends are grouped for control in pairs, with slightly differing facilities. Aux pairs 1/2 and 3/4 can each be used as independent mono sends or as a stereo pair, and if used as stereo can have an independent pan control or follow the channel pan. Pre-fade and mute buttons are included. Aux pair 5/6 is fixed post fade and can also be used as two mono or one stereo feed, but with an independent stereo pan — it can't follow the channel pan at all. However, the outputs can be sent to the channel group routing, if required, which effectively doubles the number of potential aux sends available from the desk. The final pair, 7/8, can be switched pre-fade, but are always separate mono sends — there is no stereo option at all. Above the channel aux controls are nine push buttons used to select routing to the main stereo and/or eight groups. Finally, three more buttons select the buss or tape inputs and polarity inversion, and a large rotary control adjusts the gain trim over a ±10dB range. On the master section of the desk, the eight groups are arranged across four channel-module widths, with pairs of faders in each section. Buttons are provided for solo and cut, as well as stereo pan and group insert bypasses. Above these controls are the eight aux master send level controls with cut buttons, and then four stereo effects returns, each with full routing to groups and main output, with solo and cut buttons. The main stereo output also has a switchable insert point. The monitoring section features a pair of VU meters which can be switched between the master stereo buss, the monitor selection and the solo buss. The solo monitoring can be switched between AFL/PFL and solo-in-place modes, and there is an alignment oscillator facility and switching for up to three pairs of monitoring speakers. Talkback can be routed to the first three six auxes in pairs, as well as the main output, and there is a stereo insert. Finally, the monitoring selector includes the stereo buss, aux 1/2 and three external sources. Provision is also made for sending the selected external source to aux 1/2 and to sum the monitoring to mono. A huge volume control is provided, along with a large, illuminated Dim button. The basic 5088 console is clearly primarily intended for analogue summing, remixing and mastering applications in the stereo market, allowing studios and producers to integrate their own outboard effects and signal processors, rather than forcing them to use whatever is built into the console. However, the ability to include the Portico modules, as mentioned earlier, does allow a fully specified 'traditional' console to be constructed, and gives the ability for users to create a custom-designed and -equipped remixing console, with more elaborate EQ, tape simulators, MS processing and more.

In Use

The 5012 is a delightful mic preamp. It is exceptionally quiet, even at high gain settings, and has a full bodied, solid sound that gives that slightly larger-than-life character that is the trademark of a really top-class preamp. It sounds clean and detailed in normal use, without that edgy crispness that can detract in some designs. It's not what I would call transparent or totally accurate, but it sounds pleasant and attractive, and is probably aimed more at the rock/pop market rather than the orchestral niche. When the Silk mode is switched in, the sound becomes a little smoother, rounder, and sweeter still in the upper mids. The high end gains a little more air, and the bottom end becomes a tad richer and thicker. 'Vintage' is actually a very apt description, and there is a very obvious colouration to this sound that will undoubtedly appeal to many potential users. Obviously, it's a case of horses for courses, but it's a very nice option to have.

The high-pass filter does its job well and is easy to fine-tune, and being able to bypass that stage completely when it's not required is useful. The metering is clear and informative, as are the illuminated buttons, and I can find nothing to fault with this unit at all. It does exactly what it says on the box, and to the very high standards that we have all come to expect from the Rupert Neve stable.

I'm a fan of high input impedances on microphone inputs and routinely run my Focusrite ISA428 with the impedance at its highest setting. The 10k(omega) input on the 5012 is higher than many would dare, but it does seem to work well, and there is certainly no obvious noise penalty.

If you're looking for a compact, high-performance mic preamp with top-notch performance and only the most essential facilities, this model is certainly one to consider carefully. The variable HPF and Silk mode endow it with some useful and interesting tonal character flexibility.

Portico 5033

The Portico 5033 is a single-channel 5-band equaliser, very reminiscent of the old Focusrite console channel designs. The same all-steel case is used as the 5012, and the rear panel carries a single female input XLR and a male output XLR, plus a pair of TRS sockets for the Portico buss linking, a coaxial DC power inlet and an on-off button. Both the input and output stages feature transformers, and the unit can serve as a very capable line-driver if the EQ is bypassed.

Each of the 5033's five bands has an adjustment range of ±12dB. The LF and HF bands are standard shelving filters and can be switched in or out as a pair, independently of the other EQ sections. Each of the 5033's five bands has an adjustment range of ±12dB. The LF and HF bands are standard shelving filters and can be switched in or out as a pair, independently of the other EQ sections. Each of the 5033's five bands has an adjustment range of ±12dB. The LF and HF bands are standard shelving filters and can be switched in or out as a pair, independently of the other EQ sections.

The front panel has 14 rotary controls, with slightly larger grey knobs on the centre-detented gain controls, and red caps on the frequency and Q controls. The leftmost control on the bottom row adjusts the input trim over ±12dB, and an illuminated push button above provides an overall bypass mode which removes the equalisers from circuit, but leaves the input and output buffer amplifiers.

Every band has an adjustment range of ±12dB, and the LF and HF bands are standard shelving filters that can be switched in or out as a pair, independently of the other EQ sections. The section turnover frequencies span 30-300Hz and 2.5-25kHz, respectively. The HF section has been designed to allow the introduction of 'air' and 'sparkle' to a mix, while the LF section can help to tame boomy bass instruments or help to add some weight to a thin recording.

The three middle bands are all fully parametric, with variable Q between 0.7 and 5, and overlapping frequency ranges. The LMF band spans 50-400Hz, while the MF covers 330Hz to 2.5kHz and the HMF extends between 2kHz and 16kHz. Each section has its own illuminated bypass button, although the frequency response is flat when the gain control is in its centre detent position.

The line input has a standard 10k(omega) impedance and is both floating (ground free) and balanced via the input transformer, which can accommodate signals of +20dBu without compromising low-frequency distortion. The output is also via a large transformer, driven by single-sided discrete electronics, able to produce up to +25dB at the floating output. Most of the active circuitry is built around standard NE5534 op amps running on internal ±18V rails provided by an internal DC-DC converter.

Alternatives When it comes to the 'Neve' sound, there are plenty of alternatives, most being copy-cat clones of classic 1073 and 1081 modules. But these Portico units are original designs built with the best of modern components and custom transformers, building on all of Rupert Neve's experience and knowledge to date. In that respect, they are matchless.

In Use

The 5033 is, as you would expect, very musical and sweet-sounding. Even with everything bypassed, its transformers add a certain quality to the sound — a subtle richness and fullness — which will appeal to those who feel digital recordings have an unpleasant sterile quality.

The overlapping EQ bands are well chosen and ensure that no part of the spectrum is beyond reach. The high and low shelving filters allow gentle tonal sweetening — the gentle warming of the bass region, or adding silky air to the top — while the three mid bands allow surgical correction without drawing attention to their work. The variable bandwidth allows precise or broad adjustment, and although the ±12dB range is less than many equalisers, it proved to be more than was necessary during my tests. With this equaliser, less is quite definitely more!

If you found this equaliser on a console you would never need an outboard unit again. As an outboard unit, it does a sterling job and few others can equal its sonic performance, let alone better it. The only criticism I could raise is the difficulty in matching settings accurately between a pair of units when processing a stereo signal. But I doubt that will become a real issue for the vast majority of its potential users.

Conclusion

These Portico units are extremely well engineered, mechanically and electronically. High-quality components have been used throughout — nothing really exotic, just good, solid, well-proven devices that do what they are required to do. The attention to detail and the technical specifications are faultless and generous. There is massive headroom, exceptionally low noise floors and careful grounding. There is nothing frivolous or gimmicky about anything, either. The controls and interfacing are all clearly designed by someone who understands precisely what the user needs to do with these tools. And the tools themselves do exactly what they are intended to do, effectively and flexibly. In a simple phrase, these are professional products, designed to deliver professional results to professionals who understand and appreciate what that term means. Expensive, but very desirable! 

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