Headphone Amplifier - Practical Devices Corporation
Contents
1. Signal to Noise ratio 20 20 000Hz typical 97dB 18 Dynamic Range 20 20 000HZ typical en User adjustable from mono to stereo using potentiometer Crossfeed User can bypass using pushbutton Auto Power OFF User selects between 1 3 or 6 hour poweroff interval or unit can be set to stay on indefinitely Status Indicators Two LEDS one blue one amber Integrated Voltmeter accuracy 100mV typical Mechanicals Anodized aluminum case Glossy laser anodized faceplate Polished aluminum volume knob FR 4 dual layer Printed Circuit Board with 1 oz copper Flashlight Mode Turns on both LEDs to full brightness Dimming mode Allows user to optionally dim the blue LED Other Features 19 XM3_v23 2006 PDP RA kak DEVICES CORPORATION Practical DEVICES www practicalde2. 7 times Turn on power forever 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 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 Input example if battery is at 8 5 volts the amber e E he Connect to MP3 player Output Crossfeed Enable Switch Connect to IN position Crossfeed enabled Headphones dda OUT position Crossfeed disabled Power Connector 2 5mm mono audio power jack DC polarity is not important Gold Plated Amp Chip Socket Allows for future amp chip upgrades and modifications for those who like to experiment With battery charger jumper 12 volts DC 5 or 9 volts AC RMS 5 Crossfeed Adjuster Turn this potentiometer with a small Phillips or flat screwdriver to adjust the amount of Crossfeed from near stereo to 100 mono Without batter charger jumper 6 to 20 volts DC or 5 to 16 volts AC RMS Do not exceed these voltages This only has an effect when the Crossfeed Enable Switch is in the IN position Gain Boost Jumpers Jumpers installed Jumpers not installed 10db extra boost 0db extra boost Install to enable the battery charger R
3. 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 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 removed but are placed over a single Jumpers are removed pin so they don t get lost Jumpers are installed Gain boost is disabled Gain boost is disabled Gain boost is 10dB External Power Adapters Use the power connector to connect an external power adapter that has a 2 5mm mono audio style jack When not using the battery charger feature ie Battery Charger Jumper is removed the external power supply can be B to 20 Volts DC polarity is not important or 6to 18 volts AC IMPORTANT Do not exceed the above voltages or damage to the XM3 may result Such damage is not covered under warranty Note that the ground of your external power supply will not be at the same potential as the XM3 s metal case CD Hint If you use an A
4. stereo image 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 If you need to change the Gain Boost Jumpers or Battery Charger Jumper you will need to disassemble the unit Here s how 1 Turn the unit off and remove the external power adapter if connected 2 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 dP Remove unit will slide apart from the case two screws To re assemble the unit and Pull 1 Slide
5. CORPORATION XM3 Headphone Amplifier SEE aa DEVICES User s Manual Practical DEVICES Berua kak DEVICES CORPORATION 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 amp CEO Practical Devices Corporation 2006 Practical Devices Corporation All rights reserved www practicaldevices com Table of Contents XM3 Block Diagram Connecting Your XM3 Power Button Functions Crossfeed Controls Disassembling the Unit Replacing the Battery Gain Boost Jumpers External Power Adapters Testing the Battery Charging the Battery Frequently Asked Questions Troubleshooting Warranty and Guarantee Technical Specifications ANA Block Diagram Amber LED Flashes battery voltage when Power Button is pressed 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
6. ctical Devices will refund you the original cost plus the cost of the original shipping Customer must pay for return shipping cost Further we warranty for a period of one year that our products are free from any defects in workmanship Should you have any problems we promise to make it right The fine print warranty is in effect for a period of one year Problems must be reported to sales practicaldevices com This warranty covers any defects in workmanship It does not cover abuse physical damage or the like Should you need any service please email us at sales practicaldevices com 17 Specifications Portable Audio Headphone Amplifier Weight 140 grams 4 9 oz Power Source 9 volt alkaline NiMH NiCd battery or 8 4 volt NiMH or NiCD battery and or External Power Supply External Power Supply 2 5mm mono audio connector power jack If using built in battery charger 12VDC 5 or 9V AC RMS 5 If not using battery charger 6 20VDC or 6 18VAC In all cases polarity is not important Battery Charge Time using built in 15 Hours charger typical Battery Life alkaline typical 50 hours active 2 5 years standby Maximum Gain 23 1 dB Gain Boost jumpers in 12 7 dB Gain Boost jumpers out Frequency Response 20 20 000Hz 0 8dB 0 3dB typical 3dB Point typical 21 kHz at top end 9 Hz at low end Total Harmonic Distortion 0 002 typical Intermodulation Distortion 0 0039 typical
7. ead User s manual first 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 ZO Your headphones can have an impedance of 24 to 600 ohms 5 Power Button Functions Power button _ Output GE e The power button functions are activated ere pressing repeatedly within a three second window 1 press Turn unit on The AMO 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 ZO 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 CrossFeed Controls Crossieed Enable Switch Crossfeed Adjuster ZO gese Headphone Ve O _ Output The XM3 s Crossfeed circuit simulates the sound stage of loudspeakers through your headphones e Press the Switch IN to activate Crossfeed e 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 e All the way clockwise to produce a mono signal e All the way counter clockwise to produce a near
8. ing types of rechargeable batteries can be used Nickel Metal Hydride NiMH 8 4v or 9v Nickel Cadmium NiCad 8 4v or 9v Using a 7 2v battery is not recommended as overcharging may result if the external power is applied for too long When using the battery charger the external power adapter must conform to the following Regulated 12V DC 5 or 9V RMS AC 5 Use of an external power adapter which is higher than the voltages shown above may cause battery overcharging damage to the battery and or the XM3 battery electrolyte leakage or possibly even battery explosion If in doubt measure your power adapter with a voltmeter or enquire at your local electronics store IF you are using non rechargeable Alkaline carbon or zinc battery then remove the Battery Charger Jumper IF you are using an external power adapter which is not 12VDC or 9V RMS AC then remove the Battery Charger Jumper typically take about 15 hours to Jumper recharge fully O completely flat battery will Battery Charger Install the charge jumper when O want to use the battery charger function Remove the jumper otherwise your XM3 shipped from the factory with the jumper removed 13 Frequently Asked Questions 14 Can I use a line level input to the XM3 such as from a CD player or VCR Yes the XM3 will accept a line level input Can I use the XM3 to drive speakers Usually no The XM3 was designed as a headph
9. lkaline battery with the Battery Charger Jumper removed of course and an external power adapter greater than 10 volts power will come from the adapter saving battery life When you are at home and plugged in the XM3 will operate from external power When you mobilize unplug the adapter and you benefit from the long life of the Alkaline The milliamp rating mA of the power adapter does not matter any rating can be used with the XMS A suitable 12VDC regulated power adapter is RadioShack PN 273 1773 make sure you ask for Adaptaplug E 2 5mm connector PN 273 1708 which is included with the adapter 11 Testing the Battery The XM3 also acts as a battery tester When the XMS is initially turned on the amber LED will display the battery voltage by flashing For example if the voltage is 8 5 volts the LED will flash 8 times then 5 times To see the battery voltage if the unit is already on press the power button once The XMS3 will warn you if the power falls below certain thresholds e At around 6 5 volts the amber LED will begin to flash e Below around 5 2 volts the amber LED will double flash indicating the battery is very low 12 Charging the Battery Your XM3 shipped from the factory with an Industrial Alkaline 9v battery Alternatively a rechargeable battery can be used instead of the alkaline and you can use the XM3 s integrated battery trickle charger to recharge it The follow
10. one amp and will usually not do a good job of driving speakers even small ones most speakers have impedances of around eight ohms What you are looking for is a power amplifier not a headphone amplifier For more FAQs see our website http www practicaldevices com fag htm Troubleshooting Here are some common problems and their solutions Amp does not turn on or respond to pushing the power button Disconnect the battery hold down the power button for 10 seconds then reconnect the battery Headphone volume is too quiet even with the volume knob at full Increase volume of source MP3 player If it is still too quiet then install the Gain Boost jumpers see page 10 Output is in one ear only the other channel is dead Check that all cables are completely plugged in all the way Check that your cable is a stereo cable not a mono cable 15 16 Warranty and Guarantee PRACTICAL DEVICES CORPORATION Practical Devices stands behind its products with a full no risk warranty and money back satisfaction guarantee Practical Devices offers a 30 day money back guarantee on all of our products If for any reason whatsoever you are unsatisfied with your purchase you may return it for your money back including your original shipping cost The fine print Unit must be returned within 30 days of sale Unit must be returned in the same undamaged good working order as it was received Pra
11. the unit back together make sure the circuit board slides smoothly on the case s guide rails 2 Re install the two screws Do not overtighten 3 Re install the battery and rear panel Note there is a i notch in the case d Make sure the case Ge zie is oriented so the GAK Zy notch lines up with l the pushbutton as _ shown Help I think stripped the screws when tightened them No you didn t You can gently pinch the case s screw receptacles with a pair of pliers as shown to tighten things up md wt SO 5 Z Sd Replacing the Battery It is usually easier to replace the battery by removing the rear panel instead of the front To replace the battery 1 2 3 4 Disconnect any external power adapter if connected Remove the two screws holding the rear panel Unclip and discard the old battery Hold down the power button for 10 seconds Important This discharges the circuit Connect the new battery As you connect the battery the amber LED will flash briefly If it does not flash return to step 3 The unit should be ready If it is not return to step 3 Re assemble the unit GO If the battery cable has become entangled you may need to disassemble the unit as shown on page 8 Gain Boost Jumpers With the volume knob at full your XM3 will Gain Boost Jumpers deliver 13dB of gain Additionally you can ei install the Gain Boost jumpers which will
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