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CM-HPX1 Headphone Amplifiers


RB-DHD6 Headphone Distribution Amplifiers

CM-HPR1 Headphone Amplifiers

Quick Overview

Headphone Volume Control, Passive, RJ45 Input - Jack Output
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This product allows the connection of a stereo balanced line input via a RJ45 with StudioHub+™ pinout and creates a headphone output, with level control. It is transformer balanced, and can be used with any headphones above 150Ω impedance.

The transformer ratio of 2:1 ensures that any headphone load presented at the output is reflected through to the input at a 1:4 ratio (hence a 150Ω set of headphones looks like 600Ω at the input, a suitable load for most good quality line output stages).

Block Diagram

CM-HPR1 Diagram

Connectors & Controls

Headphone Output

The stereo headphone output uses a stereo 6.35mm jack socket with the following connections:

Pin Type Connection
Tip: Left
Ring: Right
Screen: Ground

The headphone level will be at half the level of the incoming signal with the volume control at 100%.

Volume Level Control

The volume level control sets the output level of the stereo headphone socket and runs logarithmically from zero to the maximum output level.

Analogue Inputs CM-HPR1

The stereo analogue input is on a female RJ45 connector with the following standard StudioHub+™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


CM-HPR1 Technical Specification

Audio Specification


Input/Output Level Ratio: 2:1
Input/Output Impedance Ratio: 4:1
Minimum Headphone Impedance: 150Ω
Max Input Level: +28dBu
Max Output Level: +22dBu
Frequency Response: 20Hz to 20kHz, +0/-0.5dB
Noise: <-115dBu A-wgtd
Distortion Ref +8dBu (Output): <0.01%
Common Mode Rejection: >80dB


Main Stereo Input: 1 x RJ45 female StudioHub+™ pinout
Output: ¼” (6.35mm) A/B gauge 3-pole stereo jack sockets

Equipment Type

CM-HPR1: Headphone volume control, RJ45 input

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