Practical Devices XM3 User Manual

XM3

Headphone Amplifier

User’s Manual

Thank you, and congratulations on your purchase of the
XM3 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 XM3 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 C. Forest
President & CEO
Practical Devices Corporation

©2006 Practical Devices Corporation. All rights reserved.

www.practicaldevices.com

XM3 Block Diagram ....................4

Connecting Your XM3 .................5

Power Button Functions ..............6

Crossfeed Controls......................7

Disassembling the Unit................8

Replacing the Battery ..................9

Gain Boost Jumpers ..................10

External Power Adapters...........11

Testing the Battery ....................12

Charging 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 (with a
small Phillips or flat
screwdriver) 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

2.5mm mono audio power jack.
DC polarity is not important.

With battery charger jumper:
12 volts DC ± 5%, or
9 volts AC RMS ± 5%

Without batter charger jumper:
6 to 20 volts DC, or
5 to 16 volts AC RMS

Do not exceed these voltages.

Battery Charger
Jumper

Install to enable the
battery charger. Read
User’s manual first!

XM3 Block Diagram

4

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

Connecting Your XM3

1. Connect a suitable source to the input jack, as
pictured. Sources may be MP3 or CD players, or 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 XM3 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 XM3 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