Sonifex Redbox Series Instruction Manual

Manufacturers of audio & video
products for radio & TV broadcasters
Redbox
User Handbook No 3
HANDBOOK
RB-UL1 Single Stereo Unbalanced To Balanced Converters
RB-UL2 Dual Stereo UnbalancedTo Balanced Converters
RB-UL4 Quad Stereo Unbalanced To Balanced Converters
RB-LU4 Quad Stereo Balanced To Unbalanced Converter
RB-BL2 Single Bi-Directional Matching Converter
RB-BL4 Dual Stereo Bi-Directional Matching Converter
RB-PA2 Dual Stereo RIAA Phono Amplifier
RB-LI2 Stereo Line Isolation Unit
RB-PLI6 6 Way Mono Passive Line Isolation Unit

Redbox Handbook 3
Redbox User Handbook No 3
Stock Code: 30-339
Artwork: AW10833
Revision 3.01, September 2019
©Sonifex Ltd, 2019
All Rights Reserved
Sonifex Ltd, 61, Station Road, Irthlingborough,
Northants, NN9 5QE, England.
Tel: [phone]
Fax: [phone]
Email: [email protected]o.uk
Website: https://www.sonifex.co.uk
Information in this document is subject to change without notice and does not represent a
commitment on the part of the vendor. Sonifex Ltd shall not be liable for any loss or damage
whatsoever arising from the use of information or any error contained in this manual.
No part of this manual may be reproduced or transmitted in any form or by any means, electronic
or mechanical, including photocopying, recording, information storage and retrieval systems, for any
purpose other than the purchaser’s personal use, without the express written permission of Sonifex
Ltd. Unless otherwise noted, all names of companies, products and persons contained herein are
part of a completely fictitious adaptation and are designed solely to document the use of Sonifex
product.
Made in the UK by
For the latest Sonifex handbook information please visit the
Sonifex website at www.sonifex.co.uk

Contents
Contents
Product Warranty - 2 Year Extended ii
Sonifex Warranty & Liability Terms & Conditions ii
1. Definitions ii
2. Warranty ii
Unpacking Your Product iii
Repairs & Returns iv
Conformity iv
Safety & Installation of Mains Operated Equipment iv
Voltage Setting Checks iv
Fuse Rating iv
Power Cable & Connection iv
WEEE Directive v
Atmosphere/Environment v
Fitting Redboxes v
1 RB-UL1 Single Stereo Unbalanced To Balanced Converters 1
Introduction 1
System Block Diagram 1
Rear Panel Connections and Operation 1
Technical Specifications RB-UL1 2
2 RB-UL2 Dual Stereo UnbalancedTo Balanced Converters 3
Introduction 3
System Block Diagram 3
Rear Panel Connections and Operation 3
Technical Specifications RB-UL2 4
3 RB-UL4 Quad Stereo Unbalanced To Balanced Converters 5
Introduction 5
System Block Diagram 5
Rear Panel Connections and Operation 5
Technical Specifications RB-UL4 6
4 RB-LU4 Quad Stereo Balanced To Unbalanced Converter 7
Introduction 7
System Block Diagram 8
Rear Panel Connections and Operation 9
Technical Specifications RB-LU4 9
5 RB-BL2 Single Bi-Directional Matching Converter 11
Introduction 11
System Block Diagram 11
Rear Panel Connections and Operation 12
Balanced to Unbalanced Connections 12
Unbalanced to Balanced Connections 12
Technical Specifications RB-BL2 13
6 RB-BL4 Dual Stereo Bi-Directional Matching Converter 14
Introduction 14
System Block Diagram 14
Rear Panel Connections and Operation 15
Balanced to Unbalanced Connections 15
Unbalanced to Balanced Connections 16
Technical Specifications RB-BL4 16
7 RB-PA2 Dual Stereo RIAA Phono Amplifier 17
Introduction 17
System Block Diagram 17
Rear Panel Connections and Operation 18
Technical Specifications RB-PA2 19
8 RB-LI2 Stereo Line Isolation Unit 20
Introduction 20
System Block Diagram 20
Rear Panel Connections and Operation 21
Technical Specifications RB-LI2 22
9 RB-PLI6 6 Way Mono Passive Line Isolation Unit 23
Introduction 23
System Block Diagram 23
Rear Panel Connections and Operation 24
Technical Specifications RB-PLI6 25

Figures
Figures
Fig A: RB-RK1 Small Redbox Front Rack-mount Kit . v
Fig B: RB-RK2 Small Redbox Rear Rack-mount Kit. vi
Fig C: RB-RK3 Large Redbox Rear Rack-mount Kit. vi
Fig 1-1: RB-UL1 Front Panel 1
Fig 1-2: RB-UL1 System Block Diagram 1
Fig 1-3: RB-UL1 Rear Panel 2
Fig 2-1: RB-UL2 Front Panel 3
Fig 2-2: RB-UL2 System Block Diagram 3
Fig 2-3: RB-UL2 Rear Panel 4
Fig 3-1: RB-UL4 Front Panel 5
Fig 3-2: RB-UL4 System Block Diagram 5
Fig 3-3: RB-UL4 Rear Panel 6
Fig 4-1: RB-LU4 Front Panel 7
Fig 4-2: RB-LU4 System Block Diagram 8
Fig 4-3: RB-LU4 Rear Panel 9
Fig 5-1: RB-BL2 Front Panel 11
Fig 5-2: RB-BL2 System Block Diagram 11
Fig 5-3: RB-BL2 Rear Panel 12
Fig 6-1: RB-BL4 Front Panel 14
Fig 6-2: RB-BL4 System Block Diagram 14
Fig 6-3: RB-BL4 Rear Panel 15
Fig 7-1: RB-PA2 Front Panel 17
Fig 7-2: RB-PA2 System Block Diagram For a Single
Stereo Channel 17
Fig 7-3: RB-PA2 Rear Panel 18
Fig 8-1: RB-LI2 Front Panel. 20
Fig 8-2: RB-LI2 System Block Diagram 20
Fig 8-3: RB-LI2 Rear Panel 21
Fig 8-4: RB-LI2 Jumper Positions on the PCB 22
Fig 9-1: RB-PLI6 Front Panel 23
Fig 9-2: RB-PLI6 System Block Diagram 23
Fig 9-3: RB-PLI6 Rear Panel 24
Fig 9-4: RB-PLI6 Ground-link Jumper Settings 24

Warranty Registration
Sonifex Limited y 61 Station Road y Irthlingborough y Northamptonshire y NN9 5QE y United Kingdom
Tel: [phone] y Fax: [phone] y Email: [e-mail] y Internet: www.sonifex.co.uk
Register Online for an
Extended 2 Year Warranty
As standard, Sonifex products are
supplied with a 1 year back to base
warranty.
If you register the product online, you
can increase your product warranty
to 2 years and we can also keep
you informed of any product design
improvements or modifications.
To register your product, please go online to www.sonifex.co.uk/register
Product:
Serial No:

ii
Warranty
Product Warranty - 2 Year Extended
As standard, Sonifex products are supplied with a 1 year back to base
warranty. In order to register the date of purchase and so that we can keep
you informed of any product design improvements or modifications, it is
important to complete the warranty registration online. Additionally, if you
register the product on the Sonifex website, you can increase your product
warranty to 2 years. Go to the Sonifex website at: https://www.sonifex.
co.uk/technical/register/index.asp to apply for your 2 year warranty.
Note: For your own records the product serial number is recorded on the
CE certification page of this handbook.
Sonifex Warranty & Liability Terms & Conditions
1. Definitions
‘the Company’ means Sonifex Ltd and where relevant includes companies
within the same group of companies as Sonifex Limited.
‘the Goods’ means the goods or any part thereof supplied by the Company
and where relevant includes: work carried out by the Company on items
supplied by the Purchaser; services supplied by the Company; and software
supplied by the Company.
‘the Purchaser’ means the person or organisation who buys or has agreed
to buy the Goods.
‘the Price’ means the Price of the Goods and any other charges incurred by
the Company in the supply of the Goods.
‘the Warranty Term’ is the length of the product warranty which is usually
12 months from the date of despatch; except when the product has been
registered at the Sonifex website when the Warranty Term is 24 months
from the date of despatch.
‘the Contract’ means the quotation, these Conditions of Sale and any
other document incorporated in a contract between the Company and the
Purchaser.
This is the entire Contract between the parties relating to the subject
matter hereof and may not be changed or terminated except in writing in
accordance with the provisions of this Contract. A reference to the consent,
acknowledgement, authority or agreement of the Company means in
writing and only by a director of the Company.
2. Warranty
a. The Company agrees to repair or (at its discretion) replace Goods
which are found to be defective (fair wear and tear excepted) and
which are returned to the Company within the Warranty Term
provided that each of the following are satisfied:
i. notification of any defect is given to the Company immediately
upon its becoming apparent to the Purchaser;
ii. the Goods have only been operated under normal operating
conditions and have only been subject to normal use (and
in particular the Goods must have been correctly connected
and must not have been subject to high voltage or to ionising
radiation and must not have been used contrary to the
Company’s technical recommendations);
iii. the Goods are returned to the Company’s premises at the
Purchaser’s expense;
iv. any Goods or parts of Goods replaced shall become the
property of the Company;
v. no work whatsoever (other than normal and proper
maintenance) has been carried out to the Goods or any part of
the Goods without the Company’s prior written consent;

iii
Warranty
vi. the defect has not arisen from a design made, furnished or
specified by the Purchaser;
vii. the Goods have been assembled or incorporated into other
goods only in accordance with any instructions issued by the
Company;
viii. the defect has not arisen from a design modified by the
Purchaser;
ix. the defect has not arisen from an item manufactured by
a person other than the Company. In respect of any item
manufactured by a person other than the Company, the
Purchaser shall only be entitled to the benefit of any warranty
or guarantee provided by such manufacturer to the Company.
b. In respect of computer software supplied by the Company the
Company does not warrant that the use of the software will be
uninterrupted or error free.
c. The Company accepts liability:
(i) for death or personal injury to the extent that it results from the
negligence of the Company, its employees (whilst in the course
of their employment) or its agents (in the course of the agency);
(ii) for any breach by the Company of any statutory undertaking as
to title, quiet possession and freedom from encumbrance.
d. Subject to conditions (a) and (c) from the time of despatch of
the Goods from the Company’s premises the Purchaser shall be
responsible for any defect in the Goods or loss, damage, nuisance
or interference whatsoever consequential economic or otherwise or
wastage of material resulting from or caused by or to the Goods. In
particular the Company shall not be liable for any loss of profits or
other economic losses. The Company accordingly excludes all liability
for the same.
e. At the request and expense of the Purchaser the Company will test
the Goods to ascertain performance levels and provide a report of
the results of that test. The report will be accurate at the time of the
test, to the best of the belief and knowledge of the Company, and the
Company accepts no liability in respect of its accuracy beyond that
set out in Condition (a).
f. Subject to Condition (e) no representation, condition, warranty or
other term, express or implied (by statute or otherwise) is given by
the Company that the Goods are of any particular quality or standard
or will enable the Purchaser to attain any particular performance
or result, or will be suitable for any particular purpose or use
under specific conditions or will provide any particular capacity,
notwithstanding that the requirement for such performance, result or
capacity or that such particular purpose or conditions may have been
known (or ought to have been known) to the Company, its employees
or agents.
g. (i) To the extent that the Company is held legally liable to the
Purchaser for any single breach of contract, tort, representation
or other act or default, the Company’s liability for the same
shall not exceed the price of the Goods.
(ii) The restriction of liability in Condition (g)(i) shall not apply to
any liability accepted by the Seller in Condition (c).
h. Where the Goods are sold under a consumer transaction (as defined
by the Consumer Transactions (Restrictions on Statements) Order
1976) the statutory rights of the Purchaser are not affected by these
Conditions of Sale.
Unpacking Your Product
Each product is shipped in protective packaging and should be inspected
for damage before use. If there is any transit damage take pictures of the
product packaging and notify the carrier immediately with all the relevant

iv
CE Conformity
details of the shipment. Packing materials should be kept for inspection and
also for if the product needs to be returned.
The product is shipped with the following equipment so please check to
ensure that you have all of the items below. If anything is missing, please
contact the supplier of your equipment immediately.
Item Quantity
Product unit 1
IEC mains lead fitted with moulded mains plug 1
Handbook and warranty card 1
If you require a different power lead, please let us know when ordering the
product.
Repairs & Returns
Please contact Sonifex or your supplier if you have any problems with your
Sonifex product. Email [e-mail] for the repair/
upgrade/returns procedure, or for support & questions regarding the
product operation.
Conformity
The products in this manual comply with the essential requirements of the
relevant European health, safety and environmental protection legislation.
The technical justification file for this product is available at Sonifex Ltd.
The declaration of conformity can be found at:
https://www.sonifex.co.uk/declarations
Safety & Installation of Mains
Operated Equipment
There are no user serviceable parts inside the equipment. If you should
ever need to look inside the unit, always disconnect the mains supply
before removing the equipment covers. The cover is connected to earth
by means of the fixing screws. It is essential to maintain this earth/
ground connection to ensure a safe operating environment and provide
electromagnetic shielding.
Voltage Setting Checks
Ensure that the machine operating voltage is correct for your mains power
supply by checking the box in which your product was supplied. The voltage
is shown on the box label. The available voltage settings are 115V, or 230V.
Please note that all products are either switchable between 115V and 230V,
or have a universal power supply.
Fuse Rating
The product is supplied with a single fuse in the live conducting path of the
mains power input. For reasons of safety it is important that the correct
rating and type of fuse is used. Incorrectly rated fuses could present a
possible fire hazard, under equipment fault conditions. The active fuse is
fitted on the outside rear panel of the unit.
Power Cable & Connection
An IEC power connector is supplied with the product which has a moulded
plug attached.
The mains plug or IEC power connector is used as the disconnect device.
The mains plug and IEC power connector shall remain readily operable to
disconnect the apparatus in case of a fault or emergency.
The mains lead is automatically configured for the country that the product
is being sent to, from one of:

v
Safety & Installation
Fig A: RB-RK1 Small Redbox Front Rack-mount Kit .
Territory Voltage IEC Lead Type Image
UK & Middle East 230V UK 3 pin to IEC lead
Europe 230V European Schuko round 2 pin to
IEC lead
USA, Canada and
South America 115V 3 flat pin to IEC lead
Australia & New
Zealand 230V Australasian 3 flat pin to IEC lead
Connect the equipment in accordance with the connection details and
before applying power to the unit, check that the machine has the correct
operating voltage for your mains power supply.
This apparatus is of a class I construction. It must be connected to a mains
socket outlet with a protective earthing connection.
Important note: If there is an earth/ground terminal on the rear panel of
the product then it must be connected to Earth.
WEEE Directive
The Waste Electrical and Electronic Equipment (WEEE)
Directive was agreed on 13 February 2003, along with the
related Directive 2002/95/EC on Restrictions of the use of
certain Hazardous Substances in electrical and electronic
equipment (RoHS). The Waste Electrical and Electronic Equipment Directive
(WEEE) aims to minimise the impacts of electrical and electronic equipment
on the environment during their life times and when they become waste.
All products manufactured by Sonifex Ltd have the WEEE directive label
placed on the case. Sonifex Ltd will be happy to give you information about
local organisations that can reprocess the product when it reaches its “end
of use”, or alternatively all products that have reached “end of use” can be
returned to Sonifex and will be reprocessed correctly free of charge.
Atmosphere/Environment
This apparatus should be installed in an area that is not subject to excessive
temperature variation (<0°C, >50°C), moisture, dust or vibration.
This apparatus shall not be exposed to dripping or splashing, and no objects
filled with water, such as vases shall be placed on the apparatus.
Fitting Redboxes
Redboxes can be fixed to the underside of a desk, or other surfaces
using 4.2mm holes in the sides and fixed with 2 x M4 screws or 2 x No. 6
countersink wood screws.

vi
Safety & Installation
They can also be rack-mounted, with either the front, or rear of the Redbox positioned at the front of the rack (Note: this product is front rack-mounted as
standard):
Front Mounting Redboxes: For rack mounting smaller (28cm) units the optional RB-RK1 (Red) or RB-RK1B (Black) kit can be used (which include
4 off M6 panel fixing screws).
Rear Mounting a Redbox: For rear panel mounting you can use either the RB-RK2 (in this case), or RB-RK3, depending on the size of your Redbox.
Fig B: RB-RK2 Small Redbox Rear Rack-mount Kit.
Fig C: RB-RK3 Large Redbox Rear Rack-mount Kit.

1
Matching Converters - RB-UL1 1
1 RB-UL1 Single Stereo Unbalanced to Balanced Converters
Introduction
Fig 1-1: RB-UL1 Front Panel
The RB-UL1 single stereo unit is used for interfacing domestic, or semi-pro
unbalanced equipment to professional balanced line levels.
All connections are on the rear panel. The RCA unbalanced inputs have an
ŝŵƉĞĚĂŶĐĞŽĨϭϬŬɏďƌŝĚŐŝŶŐĂŶĚĂƌĞƌŽƵƚĞĚƚŽƚŚĞďĂůĂŶĐĞĚy>ZͲϯŽƵƚƉƵƚƐ
ǁŝƚŚĂŶŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏ
The RB-UL1 has two inputs & outputs.
The output gain can be individually adjusted for left and right channels
by using pre-set potentiometers accessible through the rear panel. A LED
power indicator on the front panel displays the power supply connection.
System Block Diagram
Fig 1-2: RB-UL1 System Block Diagram
Left Input
Consumer/
Unbalanced
Phono
Gain
Left Output
Professional/Balanced
Right Input
Consumer/
Unbalanced
Phono
Gain
Right Output
Professional/Balanced
Rear Panel Connections and Operation
RCA Phono Inputs (Left and Right)
The stereo left and right RCA inputs are unbalanced and have an
ŝŵƉĞĚĂŶĐĞŽĨϭϬŬɏdŚĞLJĂƌĞƌŽƵƚĞĚƚŽƚŚĞƐƚĞƌĞŽďĂůĂŶĐĞĚy>ZϯƉŝŶ
output connectors.
Outputs (Left and Right)
dŚĞy>ZϯƉŝŶŽƵƚƉƵƚƉůƵŐĐŽŶŶĞĐƚŽƌƐĂƌĞĞůĞĐƚƌŽŶŝĐĂůůLJďĂůĂŶĐĞĚǁŝƚŚĂŶ
ŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏdŚĞLJŚĂǀĞƚŚĞĨŽůůŽǁŝŶŐĐŽŶŶĞĐƚŝŽŶƐ
Pin 1: Screen
Pin 2: Phase
Pin 3: Non-phase

2
1 Matching Converters - RB-UL1
RCA
Phono Inputs
Stereo
Outputs
Output Level Adjustment
Fig 1-3: RB-UL1 Rear Panel
Equipment Type
RB-UL1: Single stereo unbalanced to balanced converter
Physical Specifications:
Dimensions (Raw): 28cm (W) x 10.8cm (D) x 4.2cm (H) (1U)
11” (W) x 4.3” (D) x 1.7” (H) (1U)
Dimensions (Boxed): 36cm (W) x 20.5cm (D) x 6cm (H)
14.2” (W) x 8” (D) x 2.4” (H)
Weight: Nett: 1.00kg Gross: 1.45kg
Nett: 2.2lbs Gross: 3.2lbs
Output Level Adjustment
The output gain can be individually adjusted for left and right channels
through pre-set potentiometers which are accessible through the rear
panel. The gain range of the unbalanced to balanced converter
is -15dBu to +15dBu ref -15dBu into the unbalanced input.
Technical Specifications RB-UL1
Audio Specifications
Maximum Input Level: +28dBu
/ŶƉƵƚ/ŵƉĞĚĂŶĐĞ хϭϬŬɏ
KƵƚƉƵƚ/ŵƉĞĚĂŶĐĞ фϱϬɏ
Maximum Output Level: +28dBu
Distortion: 0.01% THD @ 1kHz ref +8dB output
Noise: -100dB unity gain, ref +8dB output
Common Mode Rejection:
>66dB typically
&ƌĞƋƵĞŶĐLJZĞƐƉŽŶƐĞ ϮϬ,njƚŽϮϬŬ,njцϬϭĚ;ϲϬϬɏůŽĂĚƌĞĨϭŬ,njͿ
Gain Range: Balanced output: -15dBu to 15dBu, ref -15dBu
into unbalanced RCA input
Connections
Inputs: 2 x RCA phono (unbalanced)
KƵƚƉƵƚƐ Ϯdžy>ZϯƉŝŶŵĂůĞ;ďĂůĂŶĐĞĚͿ
Mains Input: Filtered IEC, 110V-120V, or 220-240V
switchable, fused, 6W maximum
Fuse Rating: Anti-surge fuse 100mA 20 x 5mm (230VAC)
Anti-surge fuse 250mA 20 x 5mm (115VAC)

3
Matching Converters - RB-UL2 2
2 RB-UL2 Dual Stereo Unbalanced to Balanced Converters
Introduction
Fig 2-1: RB-UL2 Front Panel
The RB-UL2 dual stereo unit is used for interfacing domestic, or semi-pro
unbalanced equipment to professional balanced line levels.
All connections are on the rear panel. The RCA unbalanced inputs have an
ŝŵƉĞĚĂŶĐĞŽĨϭϬŬɏďƌŝĚŐŝŶŐĂŶĚĂƌĞƌŽƵƚĞĚƚŽƚŚĞďĂůĂŶĐĞĚy>ZͲϯŽƵƚƉƵƚƐ
ǁŝƚŚĂŶŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏ
The RB-UL2 has four inputs & outputs.
The output gain can be individually adjusted for left and right channels
by using pre-set potentiometers accessible through the rear panel. A LED
power indicator on the front panel displays the power supply connection.
System Block Diagram
Fig 2-2: RB-UL2 System Block Diagram
Rear Panel Connections and Operation
RCA Phono Inputs (Left and Right)
The stereo left and right RCA inputs are unbalanced and have an impedance
ŽĨϭϬŬɏdŚĞLJĂƌĞƌŽƵƚĞĚƚŽƚŚĞƐƚĞƌĞŽďĂůĂŶĐĞĚy>ZϯƉŝŶŽƵƚƉƵƚ
connectors.
Outputs (Left and Right)
dŚĞy>ZϯƉŝŶŽƵƚƉƵƚƉůƵŐĐŽŶŶĞĐƚŽƌƐĂƌĞĞůĞĐƚƌŽŶŝĐĂůůLJďĂůĂŶĐĞĚǁŝƚŚĂŶ
ŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏdŚĞLJŚĂǀĞƚŚĞĨŽůůŽǁŝŶŐĐŽŶŶĞĐƚŝŽŶƐ
Pin 1: Screen
Pin 2: Phase
Pin 3: Non-phase
Left Input
Consumer/
Unbalanced
Phono
Gain
Left Output
Professional/Balanced
Right Input
Consumer/
Unbalanced
Phono
Gain
Right Output
Professional/Balanced

4
2 Matching Converters - RB-UL2
Output Level Adjustment
The output gain can be individually adjusted for left and right
channels through pre-set potentiometers which are accessible
through the rear panel. The gain range of the unbalanced to
balanced converter is -15dBu to +15dBu ref -15dBu into the
unbalanced input.
Technical Specifications RB-UL2
Audio Specifications
Maximum Input Level: +28dBu
/ŶƉƵƚ/ŵƉĞĚĂŶĐĞ хϭϬŬɏ
KƵƚƉƵƚ/ŵƉĞĚĂŶĐĞ фϱϬɏ
Maximum Output Level: +28dBu
Distortion: 0.01% THD @ 1kHz ref +8dB output
Noise: -100dB unity gain, ref +8dB output
Common Mode Rejection:
>66dB typically
&ƌĞƋƵĞŶĐLJZĞƐƉŽŶƐĞ ϮϬ,njƚŽϮϬŬ,njцϬϭĚ;ϲϬϬɏůŽĂĚƌĞĨϭŬ,njͿ
Gain Range: Balanced output: -15dBu to 15dBu, ref -15dBu
into unbalanced RCA input
Connections
Inputs: 4 x RCA phono (unbalanced)
KƵƚƉƵƚƐ ϰdžy>ZϯƉŝŶŵĂůĞ;ďĂůĂŶĐĞĚͿ
Mains Input: Filtered IEC, 110V-120V, or 220-240V
switchable, fused, 6W maximum
Fuse Rating: Anti-surge fuse 100mA 20 x 5mm (230VAC)
Anti-surge fuse 250mA 20 x 5mm (115VAC)
Equipment Type
RB-UL2: Dual stereo unbalanced to balanced converter
Physical Specifications:
Dimensions (Raw): 28cm (W) x 10.8cm (D) x 4.2cm (H) (1U)
11” (W) x 4.3” (D) x 1.7” (H) (1U)
Dimensions (Boxed): 36cm (W) x 20.5cm (D) x 6cm (H)
14.2” (W) x 8” (D) x 2.4” (H)
Weight: Nett: 1.05kg Gross: 1.5kg
Nett: 2.3lbs Gross: 3.3lbs
Fig 2-3: RB-UL2 Rear Panel
RCA
Phono
Inputs
Stereo
Balanced
Outputs
Stereo
Balanced
Outputs
RCA
Phono
Inputs
Output Level Adjustment

5
Matching Converters - RB-UL4 3
3 RB-UL4 Quad Stereo Unbalanced to Balanced Converters
Introduction
Fig 3-1: RB-UL4 Front Panel
The RB-UL4 quad stereo unit is used for interfacing domestic, or semi-pro
unbalanced equipment to professional balanced line levels.
All connections are on the rear panel. The RCA unbalanced inputs have an
ŝŵƉĞĚĂŶĐĞŽĨϭϬŬɏďƌŝĚŐŝŶŐĂŶĚĂƌĞƌŽƵƚĞĚƚŽƚŚĞďĂůĂŶĐĞĚy>ZͲϯŽƵƚƉƵƚƐ
ǁŝƚŚĂŶŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏ
The RB-UL4 has eight inputs & outputs.
The output gain can be individually adjusted for left and right channels
by using pre-set potentiometers accessible through the rear panel. A LED
power indicator on the front panel displays the power supply connection.
System Block Diagram
Fig 3-2: RB-UL4 System Block Diagram
Rear Panel Connections and Operation
RCA Phono Inputs (Left and Right)
The stereo left and right RCA inputs are unbalanced and have an impedance
ŽĨϭϬŬɏdŚĞLJĂƌĞƌŽƵƚĞĚƚŽƚŚĞƐƚĞƌĞŽďĂůĂŶĐĞĚy>ZϯƉŝŶŽƵƚƉƵƚ
connectors.
Outputs (Left and Right)
dŚĞy>ZϯƉŝŶŽƵƚƉƵƚƉůƵŐĐŽŶŶĞĐƚŽƌƐĂƌĞĞůĞĐƚƌŽŶŝĐĂůůLJďĂůĂŶĐĞĚǁŝƚŚĂŶ
ŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏdŚĞLJŚĂǀĞƚŚĞĨŽůůŽǁŝŶŐĐŽŶŶĞĐƚŝŽŶƐ
Pin 1: Screen
Pin 2: Phase
Pin 3: Non-phase
Left Input
Consumer/
Unbalanced
Phono
Gain
Left Output
Professional/Balanced
Right Input
Consumer/
Unbalanced
Phono
Gain
Right Output
Professional/Balanced

6
3 Matching Converters - RB-UL4
Fig 3-3: RB-UL4 Rear Panel
Output Level Adjustment
The output gain can be individually adjusted for left and right channels
through pre-set potentiometers which are accessible through the rear
panel. The gain range of the unbalanced to balanced converter is -15dBu to
+15dBu ref -15dBu into the unbalanced input.
Technical Specifications RB-UL4
Audio Specifications
Maximum Input Level: +28dBu
/ŶƉƵƚ/ŵƉĞĚĂŶĐĞ хϭϬŬɏ
KƵƚƉƵƚ/ŵƉĞĚĂŶĐĞ фϱϬɏ
Maximum Output Level: +28dBu
Distortion: 0.01% THD @ 1kHz ref +8dB output
Noise: -100dB unity gain, ref +8dB output
Common Mode Rejection:
>66dB typically
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Gain Range: Balanced output: -15dBu to 15dBu, ref -15dBu
into unbalanced RCA input
Connections
Inputs: 8 x RCA phono (unbalanced)
KƵƚƉƵƚƐ ϴdžy>ZϯƉŝŶŵĂůĞ;ďĂůĂŶĐĞĚͿ
Mains Input: Filtered IEC, 110V-120V, or 220-240V
switchable, fused, 6W maximum
Fuse Rating: Anti-surge fuse 100mA 20 x 5mm (230VAC)
Anti-surge fuse 250mA 20 x 5mm (115VAC)
Equipment Type
RB-UL4: Quad stereo unbalanced to balanced converter
Physical Specifications:
Dimensions (Raw): 48cm (W) x 10.8cm (D) x 4.2cm (H) (1U)
19” (W) x 4.3” (D) x 1.7” (H) (1U)
Dimensions (Boxed): 53cm (W) x 20.5cm (D) x 6cm (H)
21” (W) x 8” (D) x 2.4” (H)
Weight: Nett: 1.3kg Gross: 1.9kg
Nett: 2.9lbs Gross: 4.2lbs
Output Level
Adjustment
RCA
Phono
Input
Stereo
Balanced
Outputs
Stereo
Balanced
Outputs
Stereo
Balanced
Outputs
Stereo
Balanced
Outputs
RCA
Phono
Input
RCA
Phono
Input
RCA
Phono
Input
Output Level
Adjustment
Output Level
Adjustment
Output Level
Adjustment

7
Matching Converters - RB-LU4 4
4 RB-LU4 Quad Stereo Balanced to Unbalanced Converter
Introduction
Fig 4-1: RB-LU4 Front Panel
The RB-LU4 is a quad stereo unit for interfacing professional balanced
equipment to domestic, or semi-pro unbalanced line levels.
ůůĐŽŶŶĞĐƚŝŽŶƐĂƌĞŽŶƚŚĞƌĞĂƌƉĂŶĞůdŚĞĞŝŐŚƚy>ZͲϯĞůĞĐƚƌŽŶŝĐĂůůLJ
ďĂůĂŶĐĞĚŝŶƉƵƚƐŚĂǀĞĂŶŝŵƉĞĚĂŶĐĞŽĨϮϬŬɏďƌŝĚŐŝŶŐĂŶĚĂƌĞƌŽƵƚĞĚƚŽ
ĞŝŐŚƚƵŶďĂůĂŶĐĞĚZƉŚŽŶŽŽƵƚƉƵƚƐǁŝƚŚĂŶŽƵƚƉƵƚŝŵƉĞĚĂŶĐĞŽĨфϱϬɏ
The output gain can be individually adjusted for left and right channels by
using pre-set potentiometers accessible through the rear panel. An LED
power indicator is situated on the front panel, which displays the power
supply connection.

8
4 Matching Converters - RB-LU4
System Block Diagram
Left Input 1
Professional/
Balanced
Left Output 1
Consumer/Unbalanced
Phono
Gain
Right Input 1
Professional/
Balanced
Right Output 1
Consumer/Unbalanced
Phono
Gain
Left Input 2
Professional/
Balanced
Left Output 2
Consumer/Unbalanced
Phono
Gain
Right Input 2
Professional/
Balanced
Right Output 2
Consumer/Unbalanced
Phono
Gain
Left Input 3
Professional/
Balanced
Left Output 3
Consumer/Unbalanced
Phono
Gain
Right Input 3
Professional/
Balanced
Right Output 3
Consumer/Unbalanced
Phono
Gain
Left Input 4
Professional/
Balanced
Left Output 4
Consumer/Unbalanced
Phono
Gain
Right Input 4
Professional/
Balanced
Right Output 4
Consumer/Unbalanced
Phono
Gain
Fig 4-2: RB-LU4 System Block Diagram

9
Matching Converters - RB-LU4 4
Rear Panel Connections and Operation
Fig 4-3: RB-LU4 Rear Panel
Inputs 1-4 (Left and Right)
dŚĞy>ZϯƉŝŶƐŽĐŬĞƚƐƵƐĞĚĨŽƌƚŚĞůĞĨƚĂŶĚƌŝŐŚƚĐŚĂŶŶĞůŝŶƉƵƚƐŽĨ/ŶƉƵƚϭ
ĂƌĞĞůĞĐƚƌŽŶŝĐĂůůLJďĂůĂŶĐĞĚĂŶĚŚĂǀĞĂŶŝŵƉĞĚĂŶĐĞŽĨϮϬŬɏďƌŝĚŐŝŶŐdŚĞLJ
are routed to an unbalanced RCA (phono) output with an output impedance
ŽĨфϱϬɏĂĐŚy>ZŚĂƐƚŚĞĨŽůůŽǁŝŶŐĐŽŶŶĞĐƚŝŽŶƐ
Pin 1: Screen
Pin 2: Phase
Pin 3: Non-phase
RCA Phono Outputs 1-4 (Left and Right)
These RCA (phono) outputs are unbalanced and have an output impedance
ŽĨфϱϬɏ
Output Level Adjustment
The output gain can be individually adjusted for left and right channels
through pre-set potentiometers which are accessible through the rear
panel. The gain of the balanced to unbalanced converter is variable within a
range of -28dBu to +15dBu ref. -15dBu into the balanced input.
Technical Specifications RB-LU4
Audio Specifications
Maximum Input Level: +28dBu
/ŶƉƵƚ/ŵƉĞĚĂŶĐĞ;y>ZͿ хϮϬŬɏďĂůĂŶĐĞĚďƌŝĚŐŝŶŐ
KƵƚƉƵƚ/ŵƉĞĚĂŶĐĞ;ZͿфϱϬɏ
Maximum Output Level: +22dBu
Distortion: 0.01% THD @ 1kHz, ref +8dBu output
Noise: -100dB, unity gain, ref +8dBu output
Common Mode Rejection: >66dB typically
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Gain Range: Unbalanced Output: -28dBu to +15dBu, ref
 ͲϭϱĚƵŝŶƚŽďĂůĂŶĐĞĚy>ZŝŶƉƵƚ
Connections
/ŶƉƵƚƐ ϴdžy>ZϯƉŝŶĨĞŵĂůĞ;ĂůĂŶĐĞĚͿ
Outputs: 8 x RCA phono (Unbalanced)
Mains Input: Filtered IEC, 110V-120V, or 220-240V
switchable, fused, 6W maximum
RCA Phono Outputs
Stereo Balanced
Inputs Output Level Adjustment

10
4 Matching Converters - RB-LU4
Fuse Rating: Anti-surge fuse 100mA 20 x 5mm (230VAC)
Anti-surge fuse 250mA 20 x 5mm (115VAC)
Equipment Type
RB-LU4: Quad stereo balanced to unbalanced converter
Physical Specifications
Dimensions (Raw): 48cm (W) x 10.8cm (D) x 4.2cm (H) (1U)
19” (W) x 4.3” (D) x 1.7” (H) (1U)
Dimensions (Boxed): 53cm (W) x 20.5cm (D) x 6cm (H)
21” (W) x 8” (D) x 2.4” (H)
Weight: Nett: 1.3kg Gross: 1.9kg
Nett: 2.9lbs Gross: 4.2lbs