
Musikhaus Thomann
Thomann GmbH
Hans-Thomann-Straße 1
96138 Burgebrach
Germany
Telephone: +49 (0) 9546 9223-0
E-mail: info@thomann.de
Internet: www.thomann.de
03.11.2015, ID: 234787

Table of contents
1 General notes............................................................................................................................................... 4
2 Safety instructions..................................................................................................................................... 7
3 Features....................................................................................................................................................... 12
4 Installation and starting up................................................................................................................ 13
4.1 Pin assignment.................................................................................................................................. 14
5 Connections and operating elements........................................................................................... 16
6 Functions..................................................................................................................................................... 20
7 Technical specifications....................................................................................................................... 21
8 Protecting the environment.............................................................................................................. 23
Table of contents
HP4
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1 General notes
This user manual contains important information on safe operation of the device. Read and
follow all safety notes and all instructions. Save this manual for future reference. Make sure
that it is available to all persons using this device. If you sell the device to other users, be sure
that they also receive this manual.
Our products are subject to a process of continuous development. We therefore reserve the
right to make changes without notice.
General notes
headphone amplifier
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This section provides an overview of the symbols and signal words used in this user manual.
Signal word Meaning
DANGER! This combination of symbol and signal word indicates an
immediate dangerous situation that will result in death or
serious injury if it is not avoided.
CAUTION! This combination of symbol and signal word indicates a pos‐
sible dangerous situation that can result in minor injury if it
is not avoided.
NOTICE! This combination of symbol and signal word indicates a pos‐
sible dangerous situation that can result in material and
environmental damage if it is not avoided.
Warning signs Type of danger
Warning – high-voltage.
Symbols and signal words
General notes
HP4
5

Warning signs Type of danger
Warning – danger zone.
General notes
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2 Safety instructions
This device is intended to be used for amplification and distribution of signals from audio
devices and musical instruments to the connected headphones and audio devices. Use the
device only as described in this user manual. Any other use or use under other operating con‐
ditions is considered to be improper and may result in personal injury or property damage. No
liability will be assumed for damages resulting from improper use.
This device may be used only by persons with sufficient physical, sensorial, and intellectual
abilities and having corresponding knowledge and experience. Other persons may use this
device only if they are supervised or instructed by a person who is responsible for their safety.
Intended use
Safety instructions
HP4
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DANGER!
Danger for children
Ensure that plastic bags, packaging, etc. are disposed of properly and are not
within reach of babies and young children. Choking hazard!
Ensure that children do not detach any small parts (e.g. knobs or the like) from
the unit. They could swallow the pieces and choke!
Never let children unattended use electrical devices.
DANGER!
Electric shock caused by high voltages inside
Within the device there are areas where high voltages may be present. Never
remove any covers.
There are no user-serviceable parts inside.
Safety
Safety instructions
headphone amplifier
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DANGER!
Electric shock caused by short-circuit
Always use proper ready-made insulated mains cabling (power cord) with a pro‐
tective contact plug. Do not modify the mains cable or the plug. Failure to do so
could result in electric shock/death or fire. If in doubt, seek advice from a regis‐
tered electrician.
CAUTION!
Possible hearing damage
With loudspeakers or headphones connected, the device can produce volume
levels that may cause temporary or permanent hearing impairment.
Do not operate the device permanently at a high volume level. Decrease the
volume level immediately if you experience ringing in your ears or hearing
impairment.
Safety instructions
HP4
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NOTICE!
Risk of fire
Do not cover the device nor any ventilation slots. Do not place the device near
any direct heat source. Keep the device away from naked flames.
NOTICE!
Operating conditions
This device has been designed for indoor use only. To prevent damage, never
expose the device to any liquid or moisture. Avoid direct sunlight, heavy dirt, and
strong vibrations.
Safety instructions
headphone amplifier
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NOTICE!
Power supply
Before connecting the device, ensure that the input voltage (AC outlet) matches
the voltage rating of the device and that the AC outlet is protected by a residual
current circuit breaker. Failure to do so could result in damage to the device and
possibly injure the user.
Unplug the device before electrical storms occur and when it is unused for long
periods of time to reduce the risk of electric shock or fire.
Safety instructions
HP4
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3 Features
n Excellent sound quality
n Flexible switch matrix
n Four servo-balanced stereo inputs, also suitable for mono operation
n Four signal outputs, each with line and headphone jack as well as individual volume con‐
trol
n Low-noise linear operational amplifiers for transparent sound with maximum headroom at
high output level
n Integrated shielded double-regulated power supply
n Rackable 19" format (1 RU)
Features
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4 Installation and starting up
Unpack and carefully check that there is no transportation damage before using the unit. Keep
the equipment packaging. To fully protect the device against vibration, dust and moisture
during transportation or storage use the original packaging or your own packaging material
suitable for transport or storage, respectively.
Establish all connections as long as the unit is switched off. Use the shortest possible highquality cables for all connections.
The unit has been designed for rack mounting in a standard 19-inch rack; it occupies one rack
unit.
Rack mounting
Installation and starting up
HP4
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4.1 Pin assignment
Drawings and tables indicate the pin assignment of 1/4" phone plugs to be used.
Unbalanced wired TS plug:
1 Signal
2 Ground, shielding
1/4" phone sockets for signal
inputs
Installation and starting up
headphone amplifier
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Unbalanced wired TRS plug:
1 Signal
2, 3 Ground, shielding
Balanced wired TRS plug:
1 Positive signal (+)
2 Negative signal (–)
3 Ground, shielding
Installation and starting up
HP4
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5 Connections and operating elements
Front panel
Connections and operating elements
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1 VOLUME
Volume control for the line and headphone outputs.
2 PHONE
Headphone outputs (1/4" phone sockets, stereo).
3 LINE
Line outputs (1/4" phone sockets, stereo) to loop through the input signals to the connected audio equipment.
4 INPUT SOURCE
Rotary switch for the assignment of the four rear-panel audio inputs to the line and headphone outputs on the front
panel.
5 POWER
LED to indicate the operating status. This LED lights up when the unit is turned on.
Connections and operating elements
HP4
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Rear panel
Connections and operating elements
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6 IEC chassis connector with fuse holder for operating voltage supply.
7 Operating voltage selector for AC 115 V or 230 V (= factory preset).
8 ON | OFF
Mains switch to turn the device on or off.
9 LEFT (MONO)
Audio inputs (1/4" phone sockets).
For mono operation, connect the signal source to this input of the respective channel.
For stereo operation, connect the left channel of the signal source to this input of the respective channel.
10 RIGHT
Audio inputs (1/4" phone sockets).
For stereo operation, connect the right channel of the signal source to this input of the respective channel.
Connections and operating elements
HP4
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6 Functions
The device amplifies and distributes up to four input signals in mono or stereo mode to the
four integrated output channels. The output signals can be played via up to four headphones
and / or looped through to four more audio devices with line level.
Moreover, thanks to the flexible switch matrix, you can use the rotary switch INPUT SOURCE
to link or mute the inputs and outputs of the four channels to your liking. Turn the dedicated
volume knobs to adjust the channel volume within a range of 0 to 10.
Functions
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7 Technical specifications
Audio inputs 4 × 1/4" phone sockets (unbalanced)
Impedance: 47 kΩ
Peak input level: +25 dB
Gain control range: +35 dB
Headphones outputs 4 × 1/4" phone sockets (stereo)
Max. output level: 300 mW (RMS), 1 W (Peak)
Output impedance: 22 Ω
Max. gain: +20 dB
Line outputs 4 × 1/4" phone sockets (unbalanced/parallel)
Frequency response 20 Hz … 20 kHz (0 dB … –2 dB)
THD 0.02 %
Signal-to-Noise ratio
> 80 dB
Technical specifications
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Crosstalk suppression
> 68 dB @ 1 kHz, 20 dB input
Operating supply voltage
115/230 V 50/60 Hz
Power consumption 11.5 W
Fuse 5 mm× 20 mm, 0.5 A, 230 V, fast blow
5 mm× 20 mm, 1 A , 115 V, fast blow
Dimensions (W × H × D) 482.6 mm × 44.5 mm × 217 mm
Weight 3.15 kg
Technical specifications
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8 Protecting the environment
For the transport and protective packaging, environmentally friendly materials have been
chosen that can be supplied to normal recycling.
Ensure that plastic bags, packaging, etc. are properly disposed of.
Do not just dispose of these materials with your normal household waste, but make sure that
they are collected for recycling. Please follow the notes and markings on the packaging.
This product is subject to the European Waste Electrical and Electronic Equipment Directive
(WEEE). Do not dispose with your normal household waste.
Dispose of this device through an approved waste disposal firm or through your local waste
facility. When discarding the device, comply with the rules and regulations that apply in your
country. If in doubt, consult your local waste disposal facility.
Disposal of the packaging mate‐
rial
Disposal of your old device
Protecting the environment
HP4
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Musikhaus Thomann · Hans-Thomann-Straße 1 · 96138 Burgebrach · Germany · www.thomann.de