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t:+44 (0)1933 650 700
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Passive Packs
The passive packs are a range of small utility products which use
transformers to change audio input & output impedances and levels and to
distribute audio signals.
There are a range of different products to suit different needs:
CM-HPR1
Headphone Volume Control
CM-HPX1
Headphone Volume Control
CM-ULR1
Unbal to Bal Audio Converter
CM-ULX1
Unbal to Bal Audio Converter
CM-LUR1
Bal to Unbal Audio Converter
CM-LUX1
Bal to Unbal Audio Converter
CM-AESX3
3 Way Dig AES3 Splitter, XLR
CM-AESB3
3 Way Dig AES3ID Splitter, BNC
CM-MS3
3 Way Microphone Splitter
CM-MNT1 Desk Mount Panel
All of the products, along with the CM-TBU and CM-TLL, can be mounted to
the underside of a desk using the CM-MNT1 desk mount plate. This fixes to
the top side of the product and screws to the underside of a surface.
Fig B: CM-MNT1 Desk-Mount Plate With Screws
Fig A: CM-MNT1 Desk-Mount Plate Fitted On CM-ULX1
CM-ULR1 & CM-ULX1 Unbalanced to Balanced Audio
Converters
These two products allow the connection of a stereo unbalanced line input
on phono connectors to a balanced line output (RJ45 on the CM-ULR1 with
St
™
pinout, 2 x male XLRs on the CM-ULX1).
They are transformer balanced, with a 1:2 ratio, so 6dB of gain is added
to the input to help interface with the higher signal levels associated with
professional outputs.
These units are passive versions of the RB-UL1, and provide you with an
alternative to wiring an unbalanced output directly into a balanced input.
By placing one of these boxes close to the unbalanced output (before the
cable run to the balanced input), the connection will benefit from the
input device’s common mode rejection capabilities, reducing noise and
interference.
Block Diagrams
Fig 1-4: CM-ULR1 Block Diagram
Fig 1-5: CM-ULX1 Block Diagram
Connectors & Controls
RCA Phono Inputs
Both units use a stereo unbalanced line phono connector with the following
connections:
Pin Type
Connection
White Tip:
Left
White Screen:
Ground
Red Tip:
Right
Red Screen:
Ground
Analogue Outputs CM-ULR1
The stereo balanced line output is on a female RJ45 connector with the
following standard St™ pin assignments:
Pin No.
Connection
1
Left Phase
2
Left Non-Phase
3
Right Phase
4
Ground
5
N/C
6
Right Non-Phase
7
N/C
8
N/C
Analogue Outputs CM-ULX1
The stereo analogue balanced line output is on two male 3 pin XLR
connectors with the following pin assignments:
Pin 1: 0V Common
Pin 2: Phase
Pin 3: Non Phase
Technical Spec CM-ULR1/CM-ULX1
Audio Specification
Input/Output Level Ratio:
1:2
Input/Output Impedance Ratio:
1:4
Max Input Level:
+22dBu
Max Output Level:
+28dBu
Frequency Response:
20Hz to 20kHz, +0/-0.5dB
Noise:
<-100dBu A-wgtd
Distortion Ref +8dBu (Output):
<0.02%
Connections
Stereo Unbalanced Line Input
(CM-ULR1 & CM-ULX1):
2 x RCA phono connectors
Balanced Line Output (CM-ULR1):
1 x RJ45 female
St™ pinout
Balanced Line Output (CM-ULX1):
2 x male XLRs
Equipment Type
CM-ULR1:
Unbalanced to balanced audio
converter, RJ45 output
CM-ULX1:
Unbalanced to balanced audio
converter, XLR output
Physical Specification
Dimensions (Raw):
7.7cm (W) x 8.3cm (D) x 4.2cm (H)
3.0” (W) x 3.3” (D) x 1.7” (H)
Weight:
Nett: 0.22kg Gross: 0.33kg
Nett: 0.49lbs Gross: 0.73lbs
Fig 1-1: CM-ULR1 Front & Rear View
Fig 1-3: CM-ULX1 Application Diagram
1 : 2
1 : 2
Balanced Output
1 2 3 4 5 6 7 8
Unbalanced
Input
L
R
Unbalanced
Input
1 : 2
1 : 2
Balanced Output L
Balanced Output R
L
R
1
2
3
1
2
3
Fig 1-2: CM-ULX1 Front & Rear View
St™ is a registered trademark of Radio Systems Inc
s