Rupert Neve Designs MBT Master Bus Transformer

A New Analog Classic for the Master Bus

Designed as a central link between mixing and mastering, the MBT combines transformer-based analog circuits with modern tools dedicated to stereo bus processing. It captures the spirit of high-end summing processors while introducing a shelving equalizer and a "colored" optical compressor designed to interact musically.

For Mix & Mastering Engineers Seeking Controlled Character

The MBT is aimed at producers and mixers working both "in the box" and hybrid setups who want to add cohesion, weight, and controlled brilliance to the master bus, stems, or drum bus. Its philosophy encourages experimentation: engaging the EQ before or after the dynamics yields very different, always musical, results.

Creative Sections That Complement Each Other

Input and Spectrum Shaping

The Trim control +/-12 dB optimizes gain before processing. The continuous high-pass filter (15-100 Hz) cleans up sub-bass without phase distortion, preparing the ground for the equalizer.

2-Band Low-Phase-Shift Shelf Equalizer

Each band offers +/-9 dB over a 3-octave range with gentle slopes, ideal for grounding the low end (30-240 Hz) or opening up the high frequencies (3-24 kHz) while preserving punch and width.

COLOR COMP: Opto Compression and Harmonic Saturation

This optical compressor highlights the "colored" nonlinear distortion of the opto cell. Choose 2:1 for subtlety or 5:1 for a more pronounced effect. The sidechain HPF (20-350 Hz) allows the bass to breathe, the variable release (100 ms to 1.5 s) adjusts the recovery, and the BLEND control facilitates parallel compression directly on the source material.

Synergy with the "Super Silk" Section

The +20 dB Class A output gain is not just for level boosting: it also drives the interstage transformers of the "Super Silk" section to enrich harmonic texture, from subtle sheen to pronounced character.

Technical specifications

Category	stereo summing	Rack unit	2
EQ	2 channels

Input Trim	+/-12 dB, level/peak LED	Input Impedance	10 kohms
Input High-Pass Filter	sweepable from 15 Hz to 100 Hz	Noise (22 Hz - 22 kHz)	better than -95 dBu
2-Band Shelf Equalizer	gentle slopes, low phase shift, 3-octave ranges	THD+N (0 dBu at 1 kHz)	better than 0.004%
LF EQ	variable corner frequency 30 Hz to 240 Hz, +/-9 dB	THD+N (+20 dBu at 1 kHz)	better than 0.002%
HF EQ	variable corner frequency 3 kHz to 24 kHz, +/-9 dB	Maximum Input Level	+25.5 dBu
COLOR COMP Compressor	ratios 2:1 or 5:1	Channel Separation at 1 kHz	better than -95 dB
Sidechain HPF	20 Hz to 350 Hz	Frequency Response 5 Hz - 30 kHz	+/-0.1 dB
Release Time	100 ms to 1.5 s	Frequency Response 5 Hz - 60 kHz	+/-0.25 dB
BLEND	parallel compression	Frequency Response 5 Hz - 180 kHz	-3 dB
Gain Reduction Indication	green LED	Dimensions (W x D x H)	483 x 257 x 89 mm
Make-up Gain	+20 dB Class A (level matching and driving interstage transformers of the "Super Silk" section)	Weight	7 kg