Rupert Neve Designs: Portico II Master Buss Processor

Rupert Neve Designs recently debuted the Master Buss Processor, adding to their Portico II range of processors that share the all-new, discrete, high-voltage, Class A circuitry that was developed for RND's 5088 mixer (Tape Op #73). The Master Buss Processor (MBP) was conceived as a stereo mastering processor, but with its unique features and flexibility, it provides powerful two-channel processing during tracking or mixing. True to all of Rupert Neve's designs, the MBP is

comprised of discrete gain blocks with routing options to create an extremely musical and flexible device. Custom transformers, discrete amplifiers, and mastering-grade pots and switches yield the most modern Neve design to-date. The MBP goes deep, so this review will cover the main features and functions, but one must spend a considerable amount of time really getting to know such a sophisticated box.

The rear panel of the MBP simply houses an IEC power connector, a chassis ground-lift switch, a pair of unbalanced 1/4'' inserts, and transformer-balanced XLR inputs and outputs. The output transformer is the largest toroid transformer Neve has ever employed in a line-level device. Impressive operating specs include the ability to output +25 dBu levels and a frequency response that is only 3 dB down at 120 kHz and 4 Hz. Rupert Neve relentlessly strives to maintain ultra-wide bandwidth and super-low distortion (except the artistically-applied kind) in order to maintain natural, lifelike sound reproduction. The manual, which is as educational as it is informative, explains some of the philosophy behind the design.

The front panel comfortably accommodates 16 knobs and as many buttons, which are color-coded and divided into channels and processor blocks. The clean look of the front panel layout belies the sophistication of the processing power and routing possibilities of the MBP. While the knobs have familiar labels, the actual behaviors of many parameters do not follow the same old rules and will open your ears to new approaches to signal processing. This box begs the user to crack open the manual and at least gain an overview of each processing section.

The first section I tried out was the RMS compressor. Compressor adjustments include the typical ratio, attack, release, and threshold controls, as well as the now-popular blend control. Threshold and ratio are pretty straightforward, with compression ratios ranging from a gentle 1.1:1 up to a hard-limiting 40:1, and the compressor threshold ranges from -30 to +20. The blend control allows the user to mix the uncompressed signal with the compressed signal without using additional buses or any console tricks. Another modern feature included in the MBP is the ability to choose between feedback or feed-forward compression modes. In short, vintage compressors typically use the smoother-sounding feedback circuit, while modern compressors provide more envelope-shaping options, including radical pumping effects through feed-forward architecture. A FF/FB push button switch on the MBP toggles the compressor between these two modes. Time would be well spent adjusting the timing controls and ratio in each of these two modes to explore the different compression flavors for both individual tracks and stereo program material. Further control of the compressor can be achieved with the S/C HPF, or high-pass filter side-chain selector. By inserting this 250 Hz high-pass filter into the compressor's detector circuit (not the audio path), program material can be compressed without the low-frequency information causing pumping or dulling of the high frequencies. I particularly like to employ the S/C HPF for vocal submixes and bass-heavy program material. The RMS mode of the compressor has moderately fast attack times, from 20-75 ms, and moderately slow release times, which range from 100 ms to 2.2 seconds. The Peak/RMS switch in the compressor section changes the compressor detector from an RMS, or average level detector, to a combination of Peak voltage and RMS level detection, and changes the attack time to a super-fast 0.1 ms. This novel Peak/RMS mode allows very fast attack times while still minimizing the distortion artifacts typical of true Peak detection compressors.

Alongside the comprehensive compressor section, you will find only a single knob labeled Limit. This knob sets the threshold for the limiter, but once the limiter becomes active, its action is quite sophisticated. Neve has coined the term Adaptive Release Technology to the way the limiter reacts to signals. Overall, the limiter behaves much like an opto limiter - clamping down and releasing quickly on highly transient material, while responding more slowly to mellower signals, thereby retaining a musical feel, without distortion artifacts on low-frequency signals. The limiter utilizes a variable knee, which reacts to signal level by become more sharp as the signal reaches and exceeds the threshold. The attack time is set to 0.03 ms, which can effectively flatten a 20 kHz sine wave, and a soft-clipper circuit catches any transients that sneak past the limiter during the "medium knee" action circuit. Neve also notes that the limiter shares the gain circuits with the compressor, so the limiter does not add any additional circuitry to the Class A dynamics section.

Alongside the compressor controls, a pushbutton can engage one of two Texture modes, called Silk and Silk+. When the pushbutton is blue, the Silk mode adds harmonic content by actually reducing the negative feedback on the output transformer while the red Silk+ mode enhances the low and low-mid harmonic content. The Texture knob controls the Silk or Silk+ content from almost completely off to about twice the level of coloration found on the original Portico series modules, which only had Silk on/off settings. Pressing the Texture button cycles through the red, blue, and off modes. Unlike many processors that have harmonic enhancers, I found the MBP's Silk modes extremely useful for shaping the overall tone of individual instruments and stereo program material, including full mixes.

The final control for the dynamic section is the Link switch, which assigns all dynamic control for both channels to the A channel controls. The only caveat here is that the Silk mode of both channels (red, blue, or off) must be matched before the Link button is engaged, or the Silk mode will be mismatched as you cycle through Channel A's (the stereo master) settings.

Perhaps the most mysterious and the most unique feature of the MBP is the Stereo Field Editor (SFE). This section behaves like an M/S equalizer, with a few added tricks. The basic premise is that the width and depth of a stereo signal can be manipulated independently by adjusting the Width and Depth controls. Additionally, these controls can each be applied to a specific frequency band by engaging the width and depth EQ buttons and then choosing one of four bands for each control. Specific frequency bands can be made wider or narrower and the overall ambience can be adjusted using these controls. Furthermore, the width and depth, or mid and side signals, can be fed to the compressor sections using the SFE to COMP button. This mode allows compression to be applied separately to the mono component or stereo component of a signal. This feature can be very useful in applying dynamic control to the lead vocal, bass, or other center-panned instruments, or it can allow the side information (usually ambience and effects) to be enhanced. The SFE section brings a powerful set of tools to the mastering process and can also do wonders in a mix session when only a stereo drum track is available.

Once I read the manual, and then reread it a few more times, I connected the MBP to my Avid HD I/O on a stereo insert and opened some recent mix sessions. My first experience with the compressor section was on the stereo bus of a mix session for the acoustic band Leiber-Helm. After a short while of playing with the controls, I found a very nice compression setting that brought an already good-sounding mix to an even more polished level. The side-chain high-pass filter allowed me to dial in a gentle compression that worked well in broken-down verses and didn't collapse the choruses, where the drums kicked in. I tried to ignore the meters and found that effective compression settings for full mixes often only lit up only the very top segment of the compression meter. These particular mixes were acoustic band recordings, and I wanted to keep a large, open sound, so I didn't get a chance to really squash a mix like I would in a more typical rock production. The red Silk mode opened the top end of the mix nicely and almost gave the impression of spectral compression, without any harshness or bite added to the high end. Just the right amount of top-end polish could be dialed in to make the mix sound even closer to a great master. The final touch was a subtle boost from the Width control, focused by selecting the high-mid EQ band. I found similar settings really helped bring a few mixes to a level that felt more like mastered records, and not just good finished mixes. Without any processing applied, the MBP imparted almost no perceivable color to the mix, showing off its high-quality signal path and wide-open transformers. Of course, the Silk and Silk+ controls allow you to dial in some of that vintage Neve tone, if that's what the program calls for.

On individual instruments, the MBP really shows its flexibility anddepthofprocessing.Drumtrackscouldbegentlycontrolled with the RMS compressor in feedback mode, or really hit hard in Peak/RMS mode with the feed-forward mode selected. The ability to switch between those extreme settings alone makes the MBP a pretty special box. The additional tone-shaping of the high-pass filter, external side-chain insert, and of course, the tone-shaping power of the Silk modes makes the dynamic section more powerful than any other piece of gear I can think of, including any software plug-ins. Add to all that the Limiter and the Stereo Field Editor, and the Master Buss Processor truly stands alone as a powerhouse audio processor.

For tracking, mixing, and mastering, the Portico II Master Buss Processor brings a diverse set of tools that can impart an incredibly-wide range of processing, both dynamic and spectral, to any production - and at a world-class level. Rupert Neve Designs has definitely hit one out of the park with this processor. Hopefully Neve can manufacture the boxes as fast as they leave the shelves. It is not inexpensive, but the price is a bargain for the kind of tool this box shows itself to be. ($3,995; www.rupertneve.com)

-Adam Kagan <adamkagan@mac.com>