Master Buss Processor


    One of our best-selling units: Now with new black cosmetics for 2020 by popular request, celebrating the 15th Anniversary of Rupert Neve Designs.

    Based around the high voltage, discrete and class-A signal paths made famous in the 5088 Mixer and the Portico II Channel, the Portico II Master Buss Processor is a creative tool that redefines the boundaries and limitations of traditional 2-channel compression and limiting. Though originally developed for mastering applications, the MBP has quickly become a favorite of mix engineers, tracking engineers, and even FOH engineers. From mixing bass-heavy EDM to a delicate master of a chamber ensemble, it has something to offer everyone – no matter the use or genre.

    With input and output transformers designed and implemented by Mr. Rupert Neve, the high-voltage 72V topology found in the Master Buss Processor will integrate flawlessly with virtually any system. Additionally, the MBP incorporates mastering-grade detented pots throughout to fine-tune its revolutionary dynamics, tone, and stereo field controls. This new topology is a significant evolution of Mr Rupert Neve’s classic designs with appreciable benefits to headroom, dynamic range, distortion, noise, slew rate, bandwidth, and accuracy while still providing the sweet, musical performance that has been a part of countless recordings.

    The Compressor

    The MBP’s two compressor sections allow virtually limitless possibilities in dynamics for either dual mono or stereo sources, with controls for ratio, threshold, attack, release, blend, side chain HPF, limit and make up gain. When engaged, the compressor section can be used in both feed-forward and feed-back modes to provide a transparent modern response (feed-forward), or a smoother, more musical vintage response (feed-back). Peak mode alters the compressor’s attack to react to peak transients with a roughly .1ms response time. When the Peak switch is disengaged, the compressor responds to the RMS signal in conjunction with the attack and release settings. SC HPF inserts a high pass filter at 125 Hz into the side chain to deal with intense low frequencies that may skew the response of the VCA with certain songs and instruments. “Blend” creates a parallel mix between the compressed and dry signals. By mixing the compressed and dry signals, it is possible to increase the volume of quieter elements in the source material (for instance, delicate snare brushing on a track with much louder hits), while maintaining a natural dynamic feel for the louder elements.

    To further control the side chain, there is also an insert “send” and “return” that may be paired with an external EQ or other filters for additional manipulation. The “return” may also be used as a “Key” input for ducking one signal to another (for instance, a voice-over keying the compressor to duck a background music track).

    With the stereo link control engaged, Ch. A settings act as the master control for convenient operation.

    The Limiter

    The Portico II Master Buss Processor also features an extremely versatile, transparent and musical limiter. At first glance, one might scoff at the single knob operation – however, this limiter is extremely intelligent, knowing how to appropriately respond to the various signals presented to it. Our new Adaptive Release Technology is behind this revolutionary performance. Using a blend of release time constants, this limiter will simultaneously respond quickly to transient material (such as the “snap” of a snare drum) and slowly to more sluggish signals (such as a bass guitar). This configuration allows the limiter to grab a transient and let go just an instant later, while also dealing with more constant signals in a slower, more musical way. In this manner, the MBP’s limiter can provide a much more aggressive amount of limiting than typically possible, while maintaining the essential character of the music and remaining free of the modulation distortion usually found in a fast-acting limiter.

    Typically there is a tradeoff between how fast a limiter can react and the amount of modulation distortion in the lower frequencies. This is due to the lower frequencies finding their way into the side chain signal, triggering the compressor on and off very quickly, which ends up modulating the overall signal. This is interesting to look at with sine waves, but sounds quite undesirable with music. The MBP does not have this tradeoff, and one is able to have the best of both worlds: a quick, snappy response while maintaining the integrity and smoothness of the low end. In addition to the adaptive time constant circuitry, the release time is also varied with the position of the knob. As the knob is turned counter-clock-wise, the release time is increased accordingly, as typically one would want a longer release time with a larger amount of reduction.

    “It initially caught my attention because of the limiter section. I was in need of a transparent limiter before my A/D converter; one that didn’t crap out or fold up with certain types of songs. I bought it for that use, but I found myself using the piece much more than expected.”
    Michael Romanowski, Mastering Engineer

    The new limiter found in the MBP is designed to respond as fast as .03 mS in order to reduce the first half of a 20 kHz waveform over the threshold. It has a “medium knee” initial ratio and within 3 dB of the threshold attains a better than 10:1 ratio. A soft-clip circuit catches transients that may have been in the “knee” when the threshold knob is set quite high. Both the limiter and soft clipper are switched out of circuit with the knob is fully clockwise. The release times are fully automatic and adjust depending both on the average depth of limiting and the duration of the transients above the threshold. The limiters share the same discrete, class-A gain module and VCA with the compressors, so using the Limiter does not introduce more stages that the music would have to pass through. This combination of features provides exceptionally transparent limiting, and often allows twice as much gain reduction compared to other limiters before objectionable artifacts become apparent.

    The Stereo Field Editor

    The stereo field editor on the MBP takes traditional M-S techniques to new heights with width, depth and corresponding bandpass filters.

    The width control enables the user to increase or decrease the width of a stereo image (wide/mono) and adjust the amount of ambience inherent in the recording. As the width control is rotated toward wide, the amount of difference material is boosted, often resulting in more ambient material, and accentuated stereo reverbs. Conversely, the stereo field is contracted when rotated to mono, and, if the left and right channels are highly coherent (i.e. both channels include closely similar material that is in phase), this mono content is enhanced. If the phase of one of the input channels is then reversed the mono content may be virtually eliminated. Because the amount of effect the width control has is entirely dependent on the amount of stereo information in the original source material and the interplay between the stereo field editor′s other controls, listening and experimentation are essential for the best results.

    The depth control adjusts the spatial positioning of elements in the sound stage. Center-panned elements like solo instrument or vocal can be brought forward in a mix, in relation to supporting instruments. In many cases, these same elements may be virtually eliminated without adversely affecting the music bed. Used in conjunction, the depth and width controls effectively alter the perceived room ambience and dimension.

    “The MBP is a must-have. I’ve been using it inserted across my Stereo Buss in concert for the last couple of years, and to be honest I can’t live without it. I thought my mix was good…and then I added the MBP.”
    Garry Brown – FOH Engineer

    To fine tune the SFE, there are individual filters that allow a fine tuning of what information is reintroduced from the width and depth circuits, thus tailoring each effect to a specific bandwidth. For example, if one wanted to increase the amount of low frequencies in the center image, engaging the SFE Depth and Depth EQ, set to LF, would filter out everything in the Mid signal except what is below the filter point (in this case, 250 Hz), and once reintroduced to the original would result in a perceived increase in the low frequencies in the center image. It is also possible to do the same thing with the Width EQ, except instead of boosting the width, cutting it, which removes low frequencies from the Sides, tightening up the low frequency perception in the center. Using the Width EQ again, this time set to HM (or LM as the case may be), increasing the amount of band-passed Side information can provide a wonderful spreading of instruments, reverberation and background vocals, giving the illusion that the sounds are spread further out, enveloping the listener.

    Another technique available on the SFE is routing the Mid and Side signals to the Channel A and Channel B compressors, respectively. Now whatever amount of Depth or Width is introduced is first routed to the compressors, allowing the user to utilize the compressor features on the Mid and Side information. Now it is possible to not only increase the side information, but to utilize the compressor to bring up some of the low level side information, or allow the user to tame an overly expressive lead singer. With the addition of using the EQ section on the Depth and Width, a wide range of tools is available to the engineer.



    For signals below the “threshold” level that has been set, a compressor provides a linear path allowing signals to be amplified without the gain being adjusted in any way. When signals exceed the “threshold” level, the gain is reduced in a controlled manner that depends on the Ratio that has been set.


    GAIN range provided is from 0dB to +20 dB. When compression has taken place, the gain control is necessary to increase the overall gain to restore the program level.


    Musically transparent brick-wall limiting activated when the signal reaches the limiter threshold. Attack time is .03 mS in order to reduce the first half of a 20 kHz waveform over the threshold, with Serial Adaptive Release.

    Bypass All

    Hardwire bypass for MBP, including the input and output transformers


    Continuously variable control for Silk and Silk+ modes allows the engineer to fine tune the harmonic ratio and tonality of each channel


    Changes the VCA Detection from a forward feed design (fast, more accurate attack & release) to a feed back design (smoother, more musical response)

    Peak / RMS Compression Selection

    When engaged, the MBP compressor uses a combination of peak and RMS (average) detection to trigger the VCA set below 1ms. When disengaged, it follows RMS alone.

    SC HPF

    Introduces a HPF at 125Hz to the VCA side chain signal. This allows the compressor to disregard sustained low frequency content.


    Range from 1:1 to LIMIT (i.e. 40:1)


    Range from -30dBu to +20dBU

    Attack Time

    Range from 20 mS to 75 mS.

    Release / Recovery Time

    Range of RELEASE time is 100 mS to 2.5 Seconds.

    Stereo Operation

    When the LINK switch is engaged, channel A becomes the master control, and any gain reduction happens simultaneously in both channels

    LED Meters

    Four Peak LED METERS are provided that show stereo output levels and gain reduction.

    Output level meter covers the range from -10 to +22 dBu and above which is regarded as overload.

    The reduction is calibrated in dB covering the range 1 to 22 dBu, reading from top to bottom

    Side Chain Send/Return

    External compressor side chain send and return on 2 x TRS jacks. The send is always active and normalled to the return (NOTE: If the send and return are connected to a patchbay, the send should be normalled or connected to the return by default, as the compressor will not trigger if the return has no signal)


    Using the Master Buss Processor and the 5059 Satellite to Improve a Mix

    Using the MBP with Jerry Tubb at Terra Nova Mastering

    Master Buss Processor Examples


    Using compression, texture, and HMF width.. normalized. Song: “Florence” by Auroravore

    UNPROCESSED: “Florence” by Auroravore

    Using the MBP limiter on a Jazz Trio with 4dB GR

    UNPROCESSED: Jazz Trio Improv


    “One thing about us Neve MBP owners that I’ve found we all have in common is that we don’t really tell people we own one in our studios. Why? Well because it’s arguably a modern day classic compressor and we don’t want to let that secret out! It really does something other compressors can’t or don’t do that are currently on the market. ”

    “5/5 sound quality & features: I think this device will have to be pried from my cold dead hands before I will ever go another session without its use. Thank you Mr. Neve for paving the way to a brighter, smarter future and for conceiving this most ultimate of audio witchery.”

    “The MBP is a remarkable piece of analog hardware. The compressor and limiter in concert provide clean, transparent, musical and precise dynamics control along with lots of other features that let you change the sound more drastically when necessary.”

    “ “The MBP has new colors, new wrinkles on old themes, and so far I haven’t put anything through it that didn’t sound better!””

    “”It initially caught my attention because of the limiter section. I was in need of a transparent limiter before my A/D converter; one that didn’t crap out or fold up with certain types of songs. I bought it for that use, but I found myself using the piece much more than expected.” – Michael Romanowski”

    “”The most surprising feature, and one that I didn’t think I would use at all, is the ability to adjust the width or depth of selected frequency ranges…I have found it to be an excellent tool to help polish challengingly difficult songs.” – Michael Romanowski”

    “Brilliant and flexible….The Portico II sounds big with transparent effects.”

    “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.”

    “The Rupert Neve Designs Master Buss Processor is, in my opinion, a “must audition””

    Tech Specs

    Frequency Response:

    Main Output, no load,
    –3 dB @ 4 Hz
    –3 dB @ 120 kHz

    Maximum Output Level:

    Maximum output from 20 Hz to 40 kHz is +24.5 dBu.

    Total Harmonic Distortion and Noise:

    @ 1kHz, +20 dBu output: Better than 0.006%
    @ 20Hz, +20 dBu output: Better than 0.20%

    • As above, Silk Blue Engaged, Texture fully CW: Better than 2.5%
    • As above, Silk Red Engaged, Texture fully CW: Better than 3.5%
      @ 20kHz, +20 dBu output: Better than 0.020%

    Slew rate

    Better than 4 V/uS


    Threshold: Variable from -30dBu to +20dBu
    Ratio: Variable from 1.1:1 to 40:1 (LIMIT)
    Blend: Variable from 0% to 100% Compressor
    Gain: Variable from -6 dB to +20 dB
    Attack: Variable from 20 mS to 75 mS (0.1mS with “FAST”)
    Release: Variable from 100mS to 2.2 Seconds

    Power Consumption

    .65A @ 117 VAC, .35A @ 220 VAC


    5mm x 20mm, 2.5 Amp, fast acting, ceramic body – Bussman type GDA 2.5A or equivalent


    3.5”H (2U), 19”W, 12”D

    Shipping Size

    5”H (2U), 23”W, 12”D

    Shipping Weight

    20 lbs