Transformers have been the backbone of Mr. Rupert Neve’s audio circuit design philosophy. His bespoke transformers appear in virtually every Rupert Neve Design product, and the new Master Bus Transformer (MBT) is no exception. Packed with those Rupert Neve Designs (RND) transformers, the MBT’s wide range of flavorful options enhance, sweeten, widen and transform source material, making it a powerful tool for musical coloration.
Occupying two rack spaces, this ruggedly built two-channel analog unit incorporates an internal power supply with IEC connector and recessed rear-panel power switch. Audio inputs and outputs appear on balanced XLR connectors. The clearly labeled front panel is segmented into processing sections. Detented potentiometers with color-coded aluminum knobs allow consistent repeatable settings and convenient recall sheets provided in the manual can be used to record favorite configurations. Pushbuttons for each processor segment illuminate when engaged and a “bypass all” pushbutton illuminates to show all processing is bypassed — allowing for quick in/out comparisons.
The Tonal Journey Begins
The input section’s fully Class-A line amplifier, designed to cleanly drive the more colorful MBT sections, offers ample input gain with minimal color. The input section includes a variable high-pass filter with a deep 15 Hz to 100 Hz range allowing users to achieve maximum loudness without compromising sonic tonality.
Following the input section is a 2-band shelf EQ. Designed around simplicity with elegance, each band offers a three-octave range with gentle slopes and minimal phase shift. This smooth musical EQ’s subtle tonal enhancement plays well with the other sections of the MBT. The low-frequency band is variable from 30 Hz – 240 Hz, while the HF band’s range is from 3k Hz – 24k Hz and each band offers a ±9 dB gain range. When used judiciously, the EQ gives a mix just the right amount of weight and power with sparkle and clarity.
Compress with Color…
Next in line, the optical compressor breathes a new sense of life to source material by accentuating the opto cell’s colorful characteristics. Incorporating two selectable compression ratios, sweepable high-pass side-chain filter, variable threshold, and release along with 20 dB of Class-A makeup gain, the color compressor adds lush depth and vibrant character.
Selecting the Low setting chooses a smooth 2:1 compression ratio, while the High setting’s 5:1 ratio offers more punch. The adjustable 20 Hz – 350 Hz high-pass sidechain filter leaves the low frequencies intact, allowing the compressor to focus on squashing the rest of the signal. Threshold is variable from 0 dBu to +24 dBu and a gain reduction LED illuminates as signal passes the threshold. When engaged, the Color Comp introduces pleasing audible non-linear harmonic content even with just a touch of gain reduction, becoming more apparent as the compressor settings become more extreme.
The unique Blend control varies the amount of compressed vs. uncompressed signal allowing the harmonic content or dynamic range to be dialed up or down as needed.
The compressor includes 20 dB of Class-A makeup gain. Besides the typical use of matching before and after compression levels, the Class-A amplifier can be used for driving the interstage transformers found in the Super Silk section for even larger harmonic enhancements.
Width — A New Dimension…
Following the Color Compressor is the width section, designed to increase the perceived stereo image spread. Based on the RND Stereo Field Editor used on its Master Bus Processor, the Width control is additive only, offering a greater range for more extreme operation. A variable high-pass filter (50 Hz – 800 Hz) permits low frequencies to remain more centered as the mid and high frequencies are spread to create illusion of more space. Finally, Width’s subtle high-frequency taper avoids overstating harsher HF tones.
Let’s Get Silky
Silk circuitry was introduced nearly 20 years ago and is favored by Rupert Neve Design product users. Using a form of transformer saturation, Silk enhances and controls the source material’s even-and-odd-order harmonic content. Initially, Silk had a simple on/off switch to engage the process. Over time, Silk evolved adding selectable Red and Blue modes with a control to vary Silk’s texture.
The MBT introduces Super Silk, offering independent Red and Blue texture controls that can be blended, along with a variable harmonics control and switchable Zener drive. Blue accentuates harmonics in the low and low-mid frequencies adding more depth, while Red focuses on the upper mid and high frequencies adding sparkle to the mix. The Harmonics control varies the amount of saturation desired, and the Zener drive, when engaged, introduces a soft-clip circuit for more aggressive tonality.
Super Silk includes a dedicated pair of RND custom transformers, which lets users get much closer to core saturation without saturating the bespoke transformers in the output stage. I noticed, that unlike the other illuminated buttons, the Silk on-off button is purple… a natural blend of Red and Blue.
Finally, the MBT’s output stage offers a second set of transformer-coupled, Class-A amplifiers. The output stage’s -12 to +12 dB trim control works in conjunction with the input level control allowing users to gain-stage and control overall level in the unit. Pushing Input Trim level up and backing down on Output Trim hits the processors harder resulting in more overall color, while backing off on the Input Trim and boosting the Output Trim provides a more subtle overall color without the need to readjust individual processor sections.
Experimentation is the Word
I connected the MBT between the output of my console and a pair of powered monitor speakers. The user guide provides several “starting point” examples for common scenarios including R&B, rock, jazz and pop music, along with several configurations for vocals, drums, guitar, bass and piano. I played back a familiar jazz mix and starting with the equalizer, began experimenting with the settings on each section. In all cases, I found the controls to be solidly responsive and the in/out switches allowed for quick comparisons.
I configured the Color Compressor using the starting point jazz mix settings. With the compressor engaged, I noticed more vibrance in the horns and richness in the low-end.
I found that driving the compressor with a bit more input trim level (two clicks above the starting point) opened the music up a bit more.
But the real magic happened when I engaged Super Silk. I tried several variations of Silk on my program material and found it added life to the mix, making it sound vibrant and full. When I bypassed Silk, the mix fell flat and sounded dull. After some experimentation I found that setting Red about three clicks hotter than Blue and adding just a touch of harmonics gave me a very pleasing result. I did some more tweaking and found out (as the user guide stated) it’s possible push the unit too far into the weeds, resulting in undesirable distortion; however, it’s easy to go back to the starting point by referring to the recall sheets.
With my favorite settings safely recorded on my trusty recall sheet(s), I packed up the MBT for an upcoming jazz gig.
Off to the Gala
The Gala featured a 14-piece jazz band with three singers doing their version of the Rat Pack. With the MBT inserted in the main mix outputs, I balanced gain structure and started out with the “Bypass All” button engaged. I played some prerecorded big band jazz and verified levels. I engaged the MBT and… Wow! The sound opened up in the room. I could hear more detail and vibrance in the mix. The vocals shined and the instrumentation came alive, adding excitement to my live sound mix.
I was thoroughly impressed with suddenly improved new sound of my small P.A. and give the credit to having the MBT. Although dialing in the MBT to get the personalized sound desired takes some time, and the $3,999 price point puts it out of reach for many, I had a blast using it. For the touring live sound pro looking for a well-built creative tool worthy of the Rupert Neve name, the MBT is worth it.
At a Glance:
Adding Life to the Mix
The Master Bus Transformer (MBT) from Rupert Neve Designs is a transformer-based analog “color box” that adds tone, character and excitement to your mix.
Rupert Neve Designs Master Bus Transformer
PROS
- Custom Rupert Neve designed transformers
- Super Silk transformer saturation
- Optical compressor
- Class-A line amplifiers
CONS
- Steep learning curve
- No instant recall (it’s analog!)
- Pricey
SPECS (with no features engaged)
Noise (22 Hz – 22kHz): Better than -95 dBu
THD+N (0 dBu @ 1kHz): Better than 0.004%
THD+N (+20 dBu @ 1 kHz): Better than 0.002%
Maximum Input Level: +25.5 dBu
Crosstalk @ 1 kHz: Better than -95 dB
Frequency Response:
<5 Hz – 30 kHz, ±0.1 dB
<5 Hz – 60 kHz, ±0.25 dB
<5 Hz – 180 kHz, ±3 dB
I/O Connections: XLR balanced
Power: 100-240 VAC; 50/60 Hz
Dimensions (WxDxH): 19 x 10.13 x 3.5”
Shipping Weight: 17 pounds
Price: $3,999
MANUFACTURER: Rupert Neve Designs
MORE INFO: www.rupertneve.com
