Rupert Neve Designs MBT User manual

MBT
Master Bus Transformer
Operations ManualOperations Manual

1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat registers,
stoves, or other apparatus (including amplifiers) that produce heat.
9. Do not defeat the safety purpose of the polarized or grounding-type
plug. A polarized plug has two blades with one wider than the other.
A grounding-type plug has two blades and a third grounding prong.
The wide blade or the third prong are provided for your safety. If the
provided plug does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.
10. Protect the power cord from being walked on or pinched particularly at
plugs, convenience receptacles, and the point where they exit from the
apparatus.
11. Only use attachments/accessories specified by the manufacturer.
12. Use only with a cart, stand, tripod, bracket, or
table specified by the manufacturer, or sold with
the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination to
avoid injury from tip-over.
13. Unplug this apparatus during lightning storms or
when unused for long periods of time.
14. Refer all servicing to qualified service personnel. Servicing is required
when the apparatus has been damaged in any way, such as power-
supply cord or plug is damaged, liquid has been spilled or objects have
fallen into the apparatus, the apparatus has been exposed to rain or
moisture, does not operate normally, or has been dropped.
15. This apparatus shall not be exposed to dripping or splashing, and no
object filled with liquids, such as vases or beer glasses, shall be placed
on the apparatus.
16. Do not overload wall outlets and extension cords as this can result in a
risk of fire or electric shock.
17. This apparatus has been designed with Class-I construction and must
be connected to a mains socket outlet with a protective earthing
connection (the third grounding prong).
18. This apparatus has been equipped with a rocker-style AC mains power
switch. This switch is located on the rear panel and should remain
readily accessible to the user.
19. The MAINS plug or an appliance coupler is used as the disconnect
device, so the disconnect device shall remain readily operable.
20. NOTE: This equipment has been tested and found to comply with the
limits for a Class B digital device, pursuant to part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against
harmful interference in a residential installation. This equipment
generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause
harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation.
If this equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment o and
on, the user is encouraged to try to correct the interference by one or
more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and the
receiver.
• Connect the equipment into an outlet on a circuit different from
that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for
help.
CAUTION: Changes or modifications to this device not expressly
approved by Rupert Neve Designs LLC, could void the user's authority to
operate the equipment under FCC rules.
21. This apparatus does not exceed the Class A/Class B (whichever is
applicable)
limits for radio noise emissions from digital apparatus as
set out in the radio interference regulations of the Canadian Department
of Communications.
ATTENTION — Le présent appareil numérique n’émet pas de bruits
radioélectriques dépassant las limites applicables aux appareils
numériques de class A/de class B (selon le cas) prescrites dans le
réglement sur le brouillage radioélectrique édicté par les ministere des
communications du Canada.
22. Exposure to extremely high noise levels may cause permanent hearing
loss. Individuals vary considerably in susceptibility to noise-induced
hearing loss, but nearly everyone will lose some hearing if exposed to
sufficiently intense noise for a period of time. The U.S. Government’s
Occupational Safety and Health Administration (OSHA) has specified
the permissible noise level exposures shown in the following chart.
According to OSHA, any exposure in excess of these permissible limits
could result in some hearing loss. To ensure against potentially
dangerous exposure to high sound pressure levels, it is recommended
that all persons exposed to equipment capable of producing high
sound pressure levels use hearing protectors while the equipment
is in operation. Ear plugs or protectors in the ear canals or over the
ears must be worn when operating the equipment in order to prevent
permanent hearing loss if exposure is in excess of the limits set forth
here:
Important Safety Instructions
CAUTION AVIS
RISK OF ELECTRIC SHOCK. DO NOT OPEN RISQUE DE
CHOC ELECTRIQUE. NE PAS OUVRIR
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK DO NOT REMOVE COVER (OR BACK)
NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL
ATTENTION: POUR EVITER LES RISQUES DE CHOC ELECTRIQUE, NE PAS ENLEVER LE COUVERCLE. AUCUN
ENTRETIEN DE PIECES INTERIEURES PAR L'USAGER.
CONFIER L'ENTRETIEN AU PERSONNEL QUALIFIE.
AVIS: POUR EVITER LES RISQUES D'INCENDIE OU D'ELECTROCUTION, N'EXPOSEZ PAS CET ARTICLE A LA PLUIE
OU A L'HUMIDITE
WARNING — To reduce the risk of fire or electric shock, do not
expose this apparatus to rain or moisture.
Duration,
per day in
hours
Sound Level
dBA, Slow
Response
Typical Example
8 90 Duo in small club
6 92
4 95 Subway Train
3 97
2 100 Typical music via head phones
1.5 102
1 105 Siren at 10 m distance
0.5 110
0.25 or less 115 Loudest parts at a rock concert
PORTABLE CART
WARNING
The lightning flash with arrowhead symbol within an equilateral triangle is intended to
alert the user to the presence of uninsulated "dangerous voltage" within the product's
enclosure, that may be of sufficient magnitude to constitute a risk of electric shock to
persons.
Le symbole éclair avec point de flèche à l'intérieur d'un triangle équilatéral est utilisé
pour alerter l'utilisateur de la présence à l'intérieur du coffret de "voltage dangereux"
non isolé d'ampleur suffisante pour constituer un risque d'éléctrocution.
The exclamation point within an equilateral triangle is intended to alert the user of the
presence of important operating and maintenance (servicing) instructions in the
literature accompanying the appliance.
Le point d'exclamation à l'intérieur d'un triangle équilatéral est employé pour alerter
les utilisateurs de la présence d'instructions importantes pour le fonctionnement et
l'entretien (service) dans le livret d'instruction accompagnant l'appareil.
This symbol indicates that this product must not be disposed of with other waste.
Instead, it is your responsibility to dispose of your waste equipment by handing it
over to a designated collection point for the recycling of waste electrical and
electronic equipment. The separate collection and recycling of your waste equipment
at the time of disposal will help conserve natural resources and ensure that it is
recycled in a manner that protects human health and the environment. For more
information about where you can drop off your waste equipment for recycling, please
contact your local city recycling office or the dealer from whom you purchased the
product.

Table of Contents
Introduction
Block Diagram
Front Panel
Rear Panel
MBT Features
Specifications
Limited Warranty
1
1
2
4
5
8
13

MBT Block Diagram
Rupert Neve Designs Master Bus Transformer
Thank you for purchasing the Rupert Neve Designs Master Bus Transformer. We hope you enjoy using this prod-
uct as much as we have enjoyed designing and building it. The MBT features a shelving EQ, an opto compressor,
a stereo field processor and an upgraded SILK section. The MBT is designed to provide a range of tonal options
with EQ, compression, and harmonic control, ensuring it will be useful in a wide variety of both mix bus & individual
source applications.
1
2
3
INPUT L
+ - + -
+ +
HPF FREQ
+
S/C HPF
+
+
THRESHOLD
HPF
INPUT TRIM
EQUALIZER
COLORCOMP
-
CW
BLUE
CW
RED
+
GND
- +
GND
OUTPUT TRIM
- -
+
GND
+
GND
2
3
LEFT OUTPUT
SUPER SILK
2
3
RIGHT OUTPUT
BYPASS L (-) BYPASS L (+) BYPASS R (-) BYPASS R(+)
BYPASS L (-) BYPASS L (+)
OPTOCELL
+
+
BLEND
+
GAIN
+
-
+ +
CW
WIDTH
+
WIDTH
CW
CW
RELEASE
GND
RATIO LO HI
+
+
+
OPTOCELL
+
+
+
CW
CW
GND
2
3
INPUT R
BYPASS R (-) BYPASS R(+)
- -
+
HF FREQ
+
LF FREQ
CW
HF
CW
LF
- -
+ +
CW
CW
GND GND
- -
ZENER DRIVE
+
WIDTH HPF
CW
CW
BYPASS ALL
BYPASS ALL
24 22 20
0 6 9
12 16 18
INPUT LVL - L INPUT LVL - R
DRIVE
GR
CW
HARMONICS
CW

GAIN 31-detent potentiometer that controls the compressor make-up
gain within a range of 0dB to +20dB
THRESHOLD
31-detent
potentiometer that
controls the compressor
threshold range
from +24dBu to
0dBu RELEASE
31-detent potentiometer that controls the RELEASE range from 100mS to 1.5S
COMP IN Push-button switch that illuminates GREEN when the compressor is engaged
HPF FREQ
31-detent potentiometer that adjusts
the cutoff frequency for the high pass
filter within a range of 15Hz to 100Hz
INPUT LVL
LED meter that illuminates GREEN when input
signal reaches -20dBu and illuminates RED
when signal reaches +23dBu
Indication is post input trim
HPF IN
Push-button switch that engages
the variable high pass filter
LF FREQ
31-detent potentiometer that controls
the low frequency shelf within a range
of 30Hz to 240Hz
HF FREQ 31-detent potentiometer that controls the high frequency shelf within a range of 3kHz to 24kHz
S/C HPF 31-detent potentiometer that controls the side-chain high pass filter within a range of 20Hz to 350Hz
RATIO Push-button switch that selects between a 2:1 (LO) and 5:1 (HI) ratio
LF
31-detent potentiometer that controls the
low frequency shelf gain with a range of
+/- 9dB
EQ IN
Push-button switch that illuminates GREEN
when the EQ section is engaged
HF 31-detent potentiometer that controls the high frequency shelf gain with a range of +/- 9dB
GAIN REDUCTION LED meter that illuminates GREEN to indicate compressor gain reduction
INPUT TRIM
31-detent potentiometer
that controls the input level
within a range of +/- 12dB
MIN MAX
MIN MAX
MIN MAX
70Hz
15Hz 100Hz
MIN MAX
+8dB
0dB +20dB
400mS
100mS 1.5S
+12
0dBu +24dBu
110Hz
30Hz 240Hz
11kHz
3kHz
24kHz
170Hz
20Hz 350Hz
50
0 100
400Hz
50Hz 800Hz
0
-9dB +9dB
0
-9dB +9dB
0
-12dB +12dB
0
-12dB +12dB
MBT
Master Bus
Transformer
INPUT TRIM
HPF IN EQ IN SILK
IN
LR
OUTPUT TRIM
POWER
COMP
IN
RATIO WIDTH
IN
HF
LF
ZENER
DRIVE
OUTPUT
dBu
THRESHOLD RELEASE WIDTH HARMONICS
GAIN
24 22 20 18 16 12
6 0
RUPERT NEVE DESIGNS
LO
HI
EQUALIZER SUPER SILKWIDTHINPUT COLOR COMP OUTPUT
BLUE RED
HPF FREQ LF FREQ HF FREQ
GAIN
REDUCTION
L - INPUT - R
LVL
S/C HPF HPF
BYPASS
ALL
BLEND %
DRIVE
BLEND 31-detent potentiometer that controls the wet/dry mix of the compressed signal (100%) and the input signal (0%)
MBT Front Panel
2

MBT Front Panel (continued)
3
WIDTH HPF
31-detent potentiometer that controls
the WIDTH high pass filter within a
range of 50Hz to 800Hz
WIDTH IN
Push-button switch that illuminates
GREEN when WIDTH is engaged
WIDTH
31-detent potentiometer that controls the
amount of stereo field width processing
MIN MAX
MIN MAX
MIN MAX
70Hz
15Hz 100Hz
MIN MAX
+8dB
0dB +20dB
400mS
100mS 1.5S
+12
0dBu +24dBu
110Hz
30Hz 240Hz
11kHz
3kHz
24kHz
170Hz
20Hz 350Hz
50
0 100
400Hz
50Hz 800Hz
0
-9dB +9dB
0
-9dB +9dB
0
-12dB +12dB
0
-12dB +12dB
MBT
Master Bus
Transformer
INPUT TRIM
HPF IN EQ IN SILK
IN
LR
OUTPUT TRIM
POWER
COMP
IN
RATIO WIDTH
IN
HF
LF
ZENER
DRIVE
OUTPUT
dBu
THRESHOLD RELEASE WIDTH HARMONICS
GAIN
24 22 20 18 16 12
6 0
RUPERT NEVE DESIGNS
LO
HI
EQUALIZER SUPER SILKWIDTHINPUT COLOR COMP OUTPUT
BLUE RED
HPF FREQ LF FREQ HF FREQ
GAIN
REDUCTION
L - INPUT - R
LVL
S/C HPF HPF
BYPASS
ALL
BLEND %
DRIVE
BLUE
31-detent potentiometer that controls the
amount of low frequency SILK pre-emphasis
DRIVE
LED that illuminates RED when the signal level reaches
the optimal range for SILK transformer harmonics
RED
31-detent potentiometer that controls the
amount of high frequency SILK pre-emphasis
BYPASS ALL Push-button switch that illuminates RED when the MBT is hard-wire bypassed.
OUTPUT METER 16-segment LED meters that indicate OUTPUT level in dBu
SILK IN
Push-button switch that illuminates
PURPLE when SILK is engaged
HARMONICS 31-detent potentiometer that controls the amount
of SILK transformer harmonics added to the signal
ZENER DRIVE Push-button switch that illuminates AMBER when the soft clip circuitry is engaged
OUTPUT TRIM 31-detent potentiometer that controls the
OUTPUT TRIM level within a range of +/-12dB
POWER LED that illuminates GREEN when POWER is ON

GROUND LIFT
Slide switch that lifts XLR Pin 1 from
chassis ground to isolate ground
interference
POWER IEC AC Power Inlet with power switch 100-240VAC, 50/60Hz 35 Watts MAX AC Power Consumption
OUTPUT Balanced XLR outputs using custom Rupert Neve Designs transformers
INPUT Balanced XLR combo jack line inputs ZIN = 10kΩ
Model MBT
Chassis Rear Artwork P/N 710-00153 Rev C
For Chassis P/N 430-00362
1/12/2023 DA
Rupert Neve Designs, LLC Model MBT
MADE IN USA
CAUTION
Risk of Electric Shock
Disconnect from outlet
before removing cover
POWER
100-240 VAC
50/60Hz
70 Watts
INPUTOUTPUT
L RL R
GND
LIFT
MBT Rear Panel
4

5
MBT Front Panel Features
INPUT LEVEL
LED indication that illuminates GREEN when the input signal reaches -20dBu and illuminates RED to show when
the input signal reaches +23dBu. This indication is post input trim control.
INPUT TRIM
31-detent potentiometer that controls the input level within a range of +/- 12dB.
HPF FREQ
31-detent potentiometer that controls the HPF frequency within a range of 15Hz to 100Hz.
HPF IN
Push-button switch that illuminates GREEN when the 6dB/octave HPF is engaged.
LF
31-detent potentiometer that controls the Low Frequency Shelf gain within a range of +/- 9dB.
LF FREQ
31-detent potentiometer that controls the Low Frequency Shelf corner frequency within a range of 30Hz to
240Hz.
HF
31-detent potentiometer that controls the High Frequency Shelf gain within a range of +/- 9dB.
HF FREQ
31-detent potentiometer that controls the High Frequency Shelf corner frequency within a range of 3kHz to
24kHz.
EQ IN
Push-button switch that illuminates GREEN when the equalizer section is engaged.
THRESHOLD
31-detent potentiometer that controls the compressor threshold within a range of +24dBu to 0dBu.
S/C HPF
31-detent potentiometer that controls the corner frequency of the S/C HPF within a range of 20Hz to 350Hz.
COMP IN
Push-button switch that illuminates GREEN when the compressor section is engaged.
GAIN REDUCTION
LED that illuminates GREEN when gain reduction is occuring. The LED indicates compression for left and right
channels.

6
MBT Front Panel Features (continued)
RELEASE
31-detent potentiometer that controls the Release time of the compressor within a range of 100mS to 1.5S.
RATIO
Opaque push-button switch that toggles between a LO (OUT) 2:1 ratio and a HI (IN) 5:1 compressor ratio curve.
BLEND
31-detent potentiometer that controls the amount of dry (0%) vs. wet (100%) compressed signal in the audio path.
GAIN
31-detent potentiometer that controls the amount of compressor make-up gain within a range of 0dB to +20dB.
WIDTH IN
Push-button switch that illuminates GREEN when the WIDTH section is engaged.
WIDTH HPF
31-detent potentiometer that controls the corner frequency of the width processing HPF within a range of 50Hz
to 800Hz.
WIDTH
31-detent potentiometer that controls the amount of Width stereo field processing within a range of MIN to MAX.
SILK IN
Push-button switch that illuminates PURPLE when the SUPER SILK section is engaged.
BLUE
31-detent potentiometer that controls the amount of low frequency SILK pre-emphasis.
DRIVE
LED that illuminates RED when the signal level reaches the optimal range for transformer harmonics. The LED
indicates drive level for left and right channels.
RED
31-detent potentiometer that controls the amount of high frequency SILK pre-emphasis.
HARMONICS
31-detent potentiometer that controls the amount of transformer harmonics added to the audio path.
ZENER DRIVE
Push-button switch that illuminates AMBER when the soft clip circuitry is engaged.

BYPASS ALL
Push-button switch that illuminates RED when the master bypass is engaged. This master bypass is a true hard-
wire bypass that ensures the MBT will pass audio in the event that power is lost.
OUTPUT TRIM
31-detent potentiometer that controls the amount of output trim within a range of +/- 12dB.
OUTPUT METERS
Stereo 16-segment LED meters that indicate output level in dBu.
POWER
LED that illuminates GREEN when POWER is ON.
7
MBT Front Panel Features (continued)

MBT Rear Panel Features
POWER
IEC standard 3 pin grounded switched AC power inlet with an input range of 100-240 VAC. 70 Watts maximum
AC power consumption.
GND LIFT
Slide switch that lifts XLR Output Pin 1 from chassis ground to minimize ground loops.
OUTPUT
Balanced XLR outputs with custom Rupert Neve Designs transformers capable of handling up to +25.5 dBu at
1kHz.
INPUT
Balanced XLR combo jack inputs capable of handling up to +25.5 dBu at 1kHz.
8

MBT Specifications
Note: All specifications are typical, all measurements recorded using 25ft XLR output cables with Balanced
ZSOURCE = 40 ohm
Input Impedance 10 kilohm
No features Engaged
Noise (22 Hz - 22 kHz) Better than -95 dBu
THD+N (0 dBu @ 1 kHz) 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
HPF Engaged
Noise (22 Hz - 22 kHz) Better than -95 dBu
THD+N (+20 dBu @ 1 kHz) Better than 0.002%
Equalizer Engaged
Noise (22 Hz - 22 kHz) Better than -93 dBu
THD+N (+20 dBu @ 1 kHz) Better than 0.002%
Compressor Engaged
Noise (22 Hz - 22 kHz) Better than -92 dBu
THD+N (+20 dBu @ 1 kHz) Better than 0.002%
Width Engaged
Noise (22 Hz - 22 kHz) Better than -88 dBu
THD+N (+20 dBu @ 1 kHz) Better than 0.002%
9

MBT Specications (continued)
SILK Engaged
Noise (22 Hz - 22 kHz) Better than -95 dBu
THD+N (+20 dBu @ 1 kHz) Better than 0.003%
Product Dimensions (W x D x H) 19” (48.3 cm) x 10.125” (25.7 cm) x 3.5” (8.9 cm)
Shipping Dimensions (W x D x H) 22” (55.9 cm) x 18“ (45.7 cm) x 8.7” (22.1 cm)
Shipping Weight 17 lbs. (7.7 kg)
10

MBT Shelf EQ Frequency Response
11

MBT Compressor Ratio Curves
12

775-00048 Rev A
PRODUCT WARRANTY
Rupert Neve Designs warrants this product to be free from defects in materials and workmanship for a period of
three (3) years from date of purchase, and agrees to remedy any defect identified within such three year period
by, at our option, repairing or replacing the product.
LIMITATIONS AND EXCLUSIONS
This warranty, and any other express or implied warranty, does not apply to any product which has been improperly
installed, subjected to usage for which the product was not designed, misused or abused, damaged during
shipping, damaged by any dry cell battery, or which has been altered or modified in any way. This warranty is
extended to the original end user purchaser only. A purchase receipt or other satisfactory proof of date of original
purchase is required before any warranty service will be performed. THIS EXPRESS, LIMITED WARRANTY IS IN
LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, TO THE EXTEND ALLOWED UNDER APPLICABLE
STATE LAW. IN NO EVENT SHALL RUPERT NEVE DESIGNS BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF THIS PRODUCT. Some states do not allow the
exclusion or limitation of consequential damages or limitations on how long an implied warranty lasts, so this
exclusion may not apply to you.
WARRANTY SERVICE
If you suspect a defect in this product, please contact our support sta for troubleshooting by phone (512-847-
3013) or email ([email protected]). If it is determined that the device is malfunctioning, we will issue a
Return Material Authorization and provide instructions for shipping the device to our service department.
Rupert Neve Designs
PO Box 1969
Wimberley TX 78676
www.rupertneve.com
tel: [phone]
fax: [phone]