Practical Devices XM3 Bedienungsanleitung
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 Switc
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 t ese voltages.
Battery C arger
Jumper
Install to enable the
battery charger. Read
User’s manual first
XM3 Block Diagram
4
Gold-Plated Amp C ip 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 t ree 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 LE 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
CrossFeed Controls
The XM3’s Crossfeed circuit simulates the sound stage of
loudspeakers, through your headphones.
•
Press the Switch IN to activate Crossfeed.
•
Leave the button OUT for full stereo operation,
bypassing the Crossfeed circuit entirely.
Use a small screwdriver (Philips or Straightblade) to adjust
the Crossfeed Potentiometer:
•
All the way clockwise to produce a mono signal;
•
All the way counter-clockwise to produce a near-
stereo image.
Crossfeed Adjuster Crossfeed Enable Switch
Why would you want Crossfeed?
Most music is mixed to be
listened to on loudspeakers. The studio technicians mixing the recording
assume there will be alot of crosstalk, since with speakers the listener's left ear
clearly hears the right speaker's output, and vice versa. Thus, most music is mixed
with a very wide stereo soundstage.
With headphones, however, the left ear only hears the left channel, and the right ear
only hears the right channel, with nearly zero crosstalk. This can, for many recordings,
cause the soundstage to appear to be "in the center of your head". Further, some
recordings (early Beatles recordings are infamous for this) have each instrument and
vocal track panned 100% to either left or right, which can almost immediately cause
listener fatigue. Crossfeed corrects this by bleeding some of the left channel into the
right, and vice-versa.
7
To re-assemble t e unit:
1. Slide the unit back together
(make sure the circuit board
slides smoot ly on the case's
guide rails)
2. Re-install the two screws. Do
not overtighten.
3. Re-install the battery and rear
panel.
Disassembling t e Unit
Remove
two screws,
and Pull!
8
Help! I t ink I stripped t e screws
w en I tig tened t em! No, you
didn’t. You can gently pinch the case’s
screw receptacles with a pair of pliers,
as shown, to tighten things up.
If you need to c ange t e Gain Boost Jumpers or Battery
C arger Jumper, you will need to disassemble t e unit.
Here's ow:
Note: there is a
notc in the case.
Make sure the case
is oriented so the
notch lines up with
the pus button, as
shown.
1. Turn the unit off, and remove the external
power adapter if connected.
2. Remove the rear panel using a Phillips
screwdriver. Remove the battery.
3. Remove the two screws on the front panel
(use the included 5/64” allen key). Note: you
do NOT need to remove the volume knob
4. Pull on the black plastic front bezel, and the
unit will slide apart from the case.
Replacing t e Battery
It is usually easier to replace the battery by removing the rear
panel, instead of the front.
To replace the battery:
1. Disconnect any external power adapter, if connected.
2. Remove the two screws holding the rear panel.
3. Unclip and discard the old battery
4. Hold down t e power button for 10 seconds (Important!).
This discharges the circuit.
5. Connect the new battery. As you connect the battery, the amber
LED will flash briefly. If it does not flash, return to step 3.
6. The unit should be ready. If it is not, return to step 3.
7. Re-assemble the unit
If the battery cable has become entangled, you may need to
disassemble the unit as shown on page 8.
9
With the volume knob at full, your XM3 will
deliver +13dB of gain. Additionally, you can
install the Gain Boost jumpers, which will give
you an extra +10dB of gain, for a total of
+23dB.
In order to get the best possible noise floor,
you should not install the Gain Boost jumpers
unless: a) the volume of your headphones is
too quiet, and, b) you have already tried turning up the volume of your
Gain Boost Jumpers
Gain Boost Jumpers
10
Usually, the Gain Boost jumpers are only needed when using
headphones which have an impedance greater than around 150
To install or remove the Gain Boost jumpers:
1. Disassemble the unit (see page 8)
2. To install the jumpers, place a jumper of each pair of riser pins.
(Hint: if you are removing the jumpers, place each jumper over
one pin only, so you don't lose them).
3. Re-assemble the unit.
Jumpers are installed.
Gain boost is +10dB
Jumpers are removed.
Gain boost is disabled.
Jumpers are removed, but
are placed over a single
pin so they don’t get lost.
Gain boost is disabled.
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