Practical Devices XM4 User Manual
XM4
Headphone Amplifier
User’s Manual
©2007 Practical Devices Corporation. All rights reserved.
Thank you, and congratulations on your purchase of the XM4 Portable
Headphone Amplifier!
We’ve worked very hard to provide you with what may be one of
the most advanced, feature packed, and best sounding headphone
amplifiers on the market today. The XM4 is designed to be durable, flexible,
easy to use, practical, and above all, sound great. Each unit is carefully
manufactured, and then rigorously tested for performance, durability, and
sound quality.
If you have any questions that are not answered by this manual,
please feel free to send us an email. Enjoy the amp!
Yours truly,
James Forest
President & CEO
A Word About Protecting Your Hearing
:
The most
valuable piece of audio equipment you own are your ears. Smart people protect
their hearing. When using the XM4, or any headphones, get in the habit of
removing the headphones from your ears whenever you:
•
Turn the XM4 on;
•
Connect or disconnect any cables,
•
Do ANYTHING that may cause a sudden burst of loud sound.
Your only have one set of ears, and you can’t replace them. Never listen at
excessive volume. Always listen to music at reasonable volume, and most
importantly, use good common sense.
PLEASE
READ!
XM4 Block Diagram ....................4
Connecting Your XM4 .................5
Power Button Functions ..............6
Crossfeed Controls......................7
Disassembling the Unit................8
Replacing the Battery ..................9
Gain Boost Jumpers ..................10
Lithium Battery Charger.............11
External Power Supply ..............12
Testing the Battery ....................13
Frequently-Asked Questions .....14
Troubleshooting.........................15
Warranty and Guarantee ...........17
Technical Specifications ............18
3
Table of Contents
Output
Connect to
Headphones
Power Button
Press button:
1 time = Turn on power for 1 hour
3 times = Turn on power for 3 hours
6 times = Turn on power for 6 hours
7 times = Turn on power forever
2 times = Toggle flashlight mode
5 times = Toggle dimming of blue LED
Press and HOLD to turn unit off.
Press once to display battery voltage. For
example, if battery is at 8.5 volts, the amber
LED will flash 8, then 5 times.
Input
Connect to MP3 player
or other audio source.
Main Volume
Amber LED
Flashes battery voltage when Power Button
is pressed.
Flashes a one-flash warning when the battery
is low (below 6.5 volts). Flashes a two-flash
warning when the battery is very low (below
5.2 volts).
Blue LED
Indicates
power is on
Crossfeed Enable Switch
IN position: Crossfeed enabled.
OUT position: Crossfeed disabled.
Crossfeed Adjuster
Turn this potentiometer to
adjust the amount of
Crossfeed, from near-stereo
to 100% mono.
This only has an effect when
the Crossfeed Enable Switch
is in the IN position.
Power Connector
“Barrel” connector with 1.3mm
center pin. Center pin must be
positive.
Used to power and recharge
the XM4.
Battery Charger
Jumpers
Change these only if you
want to use a NiMH
battery. See Users
Manual Pages 12 and 13
XM4 Block Diagram
Gold-Plated Amp Chip Socket
Allows for future amp chip
upgrades and modifications for
those who like to experiment.
Gain Boost Jumpers
Jumpers installed: = +10db extra boost
Jumpers not installed: = +0db extra boost
Bass +6dB
4
Connecting Your XM4
1. Connect a suitable source to the input jack, as
pictured. Sources may be MP3 or CD players, iPods,
or any line-level devices.
2. Connect your headphones to the output jack.
Your headphones can have an impedance of 24 to 600 ohms.
5
6
The power button functions are activated by pressing repeatedly
within a three second window:
1 press:
Turn unit on. The XM4 turns off
automatically after one hour.
3 presses: Turn unit on for three hours.
6 presses: Turn unit on for six hours.
7 presses:
Turn unit on. The XM4 will not turn itself off.
Press and hold: Turn unit off.
The unit will respond to button presses by flashing the
blue LED once for each hour it will stay on.
Additional power button functions:
2 presses:
Toggle flashlight mode.
5 presses:
Toggle LED dimming.
Power button
Power Button Functions
Loading...