boXem Arthur 4215/E2 User manual

Arthur 4215/E2
Stereo Power Amplifier
User Manual
PLEASE READ BEFORE OPERATING THE UNIT

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Thank you
Thank you for having chosen a power amplifier designed and built by boXem in Luxembourg, in
the heart of Europe.
At boXem, our mission is to bring to your ears the music as the artists wanted it to be. Nothing is
added, nothing is removed. This is achieved thanks to a careful selection of technologies,
rigorous processes during development and manufacturing, and tireless attention to detail.
I wish you a lifetime of musical enjoyment with Arthur.
Fred Jacquot
Managing Partner at boXem sàrl

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History
Version
Date
Content
Autor
R1
04-May-21
First version
FJ
R2
20-August-22
Add details about audiosense and gain setting
FJ

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Table of content
Important Safety Instructions ................................................................................................................. 5
Connections & Controls........................................................................................................................... 7
Rear ..................................................................................................................................................... 7
Front.................................................................................................................................................... 7
Set-up ...................................................................................................................................................... 8
Installation........................................................................................................................................... 8
Connections......................................................................................................................................... 8
AC power input................................................................................................................................ 8
Inputs connections.......................................................................................................................... 8
Outputs connections ....................................................................................................................... 9
Operation .............................................................................................................................................. 10
Powering on and off.......................................................................................................................... 10
Front panel ........................................................................................................................................ 10
Gain setting ....................................................................................................................................... 10
Troubleshooting .................................................................................................................................... 11
Audio performance data ....................................................................................................................... 12
Technical data ....................................................................................................................................... 13

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Important Safety Instructions
boXem suppose que le lecteur comprend parfaitement le texte en Anglais ci-dessous. En cas de
doute veuillez contacter boXem. Une traduction vous sera envoyée sur demande.
boXem geht davon aus, dass der Leser den untenstehenden englischen Text vollständig versteht.
Im Zweifelsfall wenden Sie sich bitte an boXem. Auf Anfrage wird Ihnen eine Übersetzung
zugesandt.
boXem pressupõe que o leitor compreende plenamente o texto inglês abaixo. Em caso de dúvida,
por favor contacte boXem. Uma tradução ser-lhe-á enviada a pedido.
boXem asume que el lector entiende perfectamente el texto en inglés que aparece a continuación.
En caso de duda, póngase en contacto con boXem. Si lo solicita, se le enviará una traducción.
Throughout this document, some aspects of operation that have a potential impact on safety or
reliability are noted with the words “Warning” and “Caution”. Take particular care reading and
understanding these items. Paragraphs marked with “Warning” explain safety measures required to
maintain your personal safety. Paragraphs marked with “Caution” pertain to danger to the
equipment itself or to connected equipment. Please follow these precautions when using this
product:
1. Read these instructions.
2. Keep these instructions.
3. Follow all instructions.
4. Heed all warnings.
5. Install in accordance with the manufacturer’s instructions.
6. Use only attachments or accessories specified by the manufacturer.
7. WARNING: Dangerous voltage is inside this apparatus. Opening is only allowed by qualified
service personnel.
8. WARNING: Do not defeat the safety purpose of the safety earth connection. Use a three-
prong power cord to ensure the product is connected to safety earth. If your outlet doesn’t
allow safety earth connection, consult an electrician for replacement of the obsolete outlet.
9. WARNING: Connect only to an outlet whose voltage fits within the range indicated at the
back of the power amplifier.
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. Unplug this apparatus during lightning storms or when unused for long periods of time.
12. WARNING: Do not use this apparatus near water. Do not expose the apparatus to dripping or
splashing. Do not place objects filled with liquids (flower vases, drink cans, coffee cups, etc)
on the apparatus. Do not use this apparatus out of doors.
13. WARNING: Clean only with a dry, soft, lint-free cloth. Do not spray any liquid cleaner onto
the cabinet, as this may lead to dangerous shocks or malfunction.
14. CAUTION: This unit runs slightly warm when operated normally. Operate in a normally
ventilated area.

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15. CAUTION: Do not install near any heat sources such as radiators, heat registers, stoves, or
other apparatus (including amplifiers) that produce heat. Avoid exposure to direct sunlight.
16. Use only with a cart, stand, bracket, or table designed for use with electronic equipment. In
any installation, make sure that injury or damage will not result from cables pulling on the
apparatus and its mounting.
17. Refer all servicing to qualified service personnel. Servicing is required when the apparatus
has been damaged in any way, such as when the power-supply 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.
18. WARNING: To reduce the risk of fire or electric shock, do not expose this apparatus to rain or
moisture.

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Connections & Controls
Rear
#
Function
Comment
1
Mains power input
IEC C14 socket –Matching IEC C13 plug
2
Mains power switch
3
Input B –Audiosense
XLR female
4
Output B
3 ways binding post
5
Output A
3 ways binding post
6
Input A
XLR female
7
Gain setting switch
High = high gain –Mid = low gain –Low = medium gain
Front
#
Function
Comment
8
Indicator LED
Off –Blink –On
1
2
3
4
5
6
7
8

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Set-up
Installation
This product relies on free convection of air along the sides and top for cooling. Avoid placing
magazines, books or other objects on top of the product as this acts as thermal insulation.
Installation inside a cupboard is permissible provided at least 30cm (12”) of free space above the
product and 10cm (4”) around the sides is respected. Operation in closer quarters requires some
provision of forced convection (fan) to be installed inside the cupboard.
Connections
CAUTION: Whenever you are plugging or unplugging cables, make sure that the power amp is off.
Failure to take this precaution may result in pops or bangs in the loudspeaker. Use properly
shielded interconnects with reliable connectors.
AC power input
Connect a power cord with IEC C13 plug on amplifier side to the AC input socket (1) on the rear
panel. Do not connect the power cord until all the audio input and output connections have been
made.
It is usually best to plug the product directly into a wall outlet. Avoid the use of extension cords. A
heavy-duty multi-tap power outlet strip may be used if it and the wall outlet are rated to handle the
total current demanded by the components connected to it.
If you are going to be away from home for an extended period of time such as a month-long
vacation, it is a sensible precaution to unplug electronic equipment. Do the same as a precautionary
measure during thunderstorms. No amount of surge protection or mains filtering will save your
equipment from a lightning strike in the backyard.
Inputs connections
The inputs are of XLR type. In the case when your preamp/DAC would be equipped with RCA
connectors only, please use interconnects wired as following:

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When connecting only one channel of the amplifier, the channel A (6) shall be chosen since it has the
Audiosense functionality allowing to automatically power on and off the amplifier.
Outputs connections
Connect the speaker negative input to the amplifier black binding.
Connect the speaker positive input to the amplifier black and red binding.
Instead of the usual L (left) and R (right) channels, your amplifier references the channels with letters
A and B. Ouput A (5) is the amplified signal from Input A (6). Ouput B (4) is the amplified signal from
Input B (3).
You can connect any output (left or right) from your preamp or DAC to Input A (6) as long as the
corresponding speaker is connected to Output A (5). The same reasoning applies for channel B.

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Operation
Powering on and off
The mains power switch (2) shall be used for powering the amplifier and completely switching it off.
Using the mains power switch to switch off the amplifier after listening to music is not mandatory
since the audiosense function will take care of it.
The audiosense function powers the main supply and the amplification stages as soon as a signal in
the audio range frequencies is detected on input A (6). When no such signal is detected during 10
minutes, the main supply and amplification stages are disconnected, allowing the amplifier to go in
standby with ultra-low power consumption.
Front panel
The indicator LED (8) has three modes:
-Off: the amplifier is unpowered of in standby
-Blinking: the amplification stage is in initialization phase
-On: the amplifier is ready to play music
Gain setting
The purpose of the gain setting is to adapt the sensitivity of the amplifier to the preamp or DAC
connected.
The theoretical way of setting the gain of the amplifier is to choose the highest sensitivity below the
maximum output of the preamp or DAC.
We propose another method, more pragmatic and providing good results:
1. Set the gain switch to low
2. Play not too compressed music
3. Raise the volume of the preamp/DAC until you reach -3 dB or the volume is too loud for your
taste
4. If the loudness made you stop increasing the volume, you are done
5. Otherwise, lower the volume and set the gain switch to medium
6. Repeat operations 2 and 3
7. If the loudness made you stop increasing the volume, you are done
8. Otherwise, lower the volume and set the gain switch to high
Another advantage of this method is that the gain of the amplifier will be the lowest possible,
ensuring a better protection for your speakers in case of false manipulation.

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Troubleshooting
Most difficulties in audio systems are the result of incorrect connections, or improper control
settings. If you encounter problems, isolate the area of the difficulty, check the control settings,
determine the cause of the fault and make the necessary changes. If you are unable to get sound
from your amplifier or its behavior is not as expected, refer to the suggestions for the following
conditions:
No response to the mains switch: Verify the mains connection. Unplug the power cable from the
Kaluga and try to power another device with it. If this works, please contact us. The unit may need
repair.
The unit responds (as witnessed by lights and clicking relays) but no sound: Verify correct speaker
wiring.
Quiet, distorted sound with interruptions: You probably have a short across the speaker or amplifier
terminals, for instance two uninsulated spade terminals touching. Reinstall your speaker cable.
The indicator LED blinks slowly and never goes to permanently on: Switch off the amplifier with the
mains power switch. Wait 10 minutes. Switch on the amplifier with the mains power switch. If the
problem still appears, please contact us. The unit may need repair.

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Audio performance data
Item
Typical value
Unit
Comment
Maximum power
210
W
In 8 Ω- measured with 230V mains
THD+N
< 0.001
%
1 –100W 20 –20000Hz
SNR
127 –125 –123
dB
Low –medium –high gain
Residual noise
17 –22 –28
µV
Low –medium –high gain
Frequency response
0 –60
kHz
0 –-3 dB
Gain
12.8 –20.8 –27.2
dB
Low –medium –high gain
Minimal load
< 2
Ω
Input sensitivity
9.4 –3.74 –1.79
V RMS
In 8 Ω- measured with 230V mains

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Technical data
Item
Value
Comment
Supply voltage 1
180 –264 VAC 47 –60 Hz
Pending market
Supply voltage 2
90 –132 VAC 47 –60 Hz
Pending market
Power consumption
1350 –12.5 –<0.5 W
Maximum –idling - standby
Dimensions
224 x 80 x 318 mm
W x H x D
Weight
4.5 kg
End of document