(2.2MB pdf., ver35) - Practical Devices Corporation
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1. ask for Adaptaplug H PN 273 1711 which is included with the adapter NiMH or NiCd Rechargeable Batter A rechargeable NiMH or NiCd battery can be used instead of the alkaline and you can use the XM4 s integrated battery trickle charger to recharge it RadioShack 23 529 battery will work or any of the following types of rechargeable batteries can be used Nickel Metal Hydride NiMH 8 4v or 9v Nickel Cadmium NiCad 8 4v or 9v Barrel type plug Using a 7 2v battery is not recommended as overcharging center may result if the external power is applied for too long in To use the trickle charger and a NiMH or NiCd battery 1 Obtain an external power supply described above 2 Install the NiMH or NiCd battery in the XM4 3 Set the Charge Jumpers in the XM4 as shown on bottom center of Page 13 e Charging a NiMH or NiCd battery will take approximately 15 hours e Battery life depends on the mAHr rating of your battery For example a 250mAHr battery can be expected to last approximately 25 hours Use of an external power supply which is higher than the voltages shown above may cause battery overcharging damage to the battery and or the XM4 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 12 Testing the Battery The XM4 also acts as a battery tester When the XM4 is turned on the am2. 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 Option Lithium Rechargeable System External Power Supply 1 3mm Barrel connector power jack center pin positive lt If using built in NiMH battery charger 12VDC 5 If not using battery charger 6 15VDC Optional Lithium charger can also be used Battery Charge Time Lithium Charge System 2 hours Trickle charge NiMH 15 hours Battery Life typical Alkaline 50 hours Lithium 40 hours Maximum Gain 23 1 dB Gain Boost jumpers in 12 7 dB Gain Boost jumpers out Frequency Response 20 20 000Hz 0 1dB 0 4dB typical 3dB Point typical 21 kHz at top end 9 Hz at low end Total Harmonic Distortion 0 002 typical Intermodulation Distortion 0 007 typical Signal to Noise ratio 18 20 20 000Hz typical Muda Specifications Conti
3. SEK ka DEVICES CORPORATION XM4 Headphone Amplifier Wid Headphone AMEN NET User s Manual Practical DEVICES PRACTICAL DEVICES CORPORATION 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 READ James Forest President amp CEO 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 e Turn the XM4 on e Connect or disconnect any cables Yours s A Word About Protecting Your Hearing the most removing the headphones from your ears whenever you e 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 2007 Practical Devices Corporation All rights reserved Table of Contents XM4 Block Diagram Connect
4. ber 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 ED The XM4 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 Charge Jumper Configuration Only change the charge jumpers from their factory defaults if you want to install a NiMH or NiCd rechargeable battery For advanced users only Alkaline Battery Configuration Trickle Charger Lithium Battery Fastcharge Both jumpers are removed Use Configuration For NiMH Both jumpers are installed this configuration if you are using and NiCd rechargeable This is the Factory default for an Alkaline battery This is the batteries Install the outer XM4 s shipped with the Lithium Factory default for XM4 s one jumper as shown option shipped with an alkaline battery Frequently Asked Questions 14 Can use a line level input to the XM4 such as from a CD DVD player or VCR Yes the XM4 will accept a line level input Can I use the XM4 to drive speakers Usually no The XM4 was designed as a headphone amp and will usually not do a good job of driving speakers even small ones most speakers have impedances of around eight ohms Wha
5. came equipped with the optional Lithium rechargeable system just plug the charger into the powerjack on the rear of the XM4 The battery will fully charge within two hours When charging is finished the LED on the charger will turn from red to green The battery will charge even if the XM4 is turned on You can leave the charger connected indefinitely You can expect up to 40 hours of use per charge Your Charger is a World charger it will work with AC Mains voltages from 105 to 240 VAC at 50 or 60Hz If you are using the charger outside of North America you may need a plug adapter available from your local electronics store 11 External Power Supply Note If your XM4 came equipped with the Lithium rechargeable system then this page does not apply to you External Power Suppl If your XM4 did NOT come with the Lithium system then it shipped from the factory with an Industrial Alkaline 9v battery You can use an external power supply to save battery life while you are at home The external power supply must be e 6 to 15V DC if you want to use the supply to recharge a NiMH or NiCd battery then the supply must be Regulated 12V DC 5 e Have a barrel type connector with a 1 3mm center pin The center pin must be positive polarity lt e The milliamp mA rating on the supply does not matter any mA rating can be used e A suitable power supply is RadioShack PN 273 1773 make sure you
6. hannel 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 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 From the rear push the circuitboard out the Remove two screws and push front of the case circuitboard To re assemble the unit from rear 1 Slide 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 notch in the case Make sure the case N is oriented so the notch lines up with the pushbutton as 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 A SEE Ge Euba FA as shown to tighten things up EN A S Circuit Board slides into s THIS slot a Replacing the Battery Replace the battery by removing the rear panel using a Philips screwdriver e Connect the battery clip to the new battery e Insert the battery clip first into the XM4 e The batte
7. ing Your XM4 Power Button Functions Crossfeed Controls Disassembling the Unit Replacing the Battery Gain Boost Jumpers Lithium Battery Charger External Power Supply Testing the Battery Frequently Asked Questions Troubleshooting Warranty and Guarantee Technical Specifications XM4 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 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 2 times Toggle flashlight mode 5 times Toggle dimming of blue LED Blue LED Indicates power is on Press and HOLD to turn unit off Press once to display battery voltage For x example if battery is at 8 5 volts the amber dd amp ari Headphone LED will flash 8 then 5 times Amplifier Ga f S 3 e d E 2 X Input Connect to MP3 player or other audio source Output Connect to Headphones Bass 6dB Crossfeed Enable Switch D IN position Crossfeed enabled OUT position Crossfeed disabled Power Connector Barrel connector with 1 3mm center pin Center pin must be Gold Plated Amp Chip Socket positive Allows for future amp ch
8. ip Used to power and recharge upgrades and modifications for the XM4 those who like to experiment Crossfeed Adjuster Turn this potentiometer to adjust the amount of Crossfeed from near stereo Battery Charger to 100 mono Jumpers Change these only if you This only has an effect when Want to use a NiMH the Crossfeed Enable Switch battery See Users is in the IN position Manual Pages 12 and 13 Gain Boost Jumpers Jumpers installed Jumpers not installed 10db extra boost 0db extra boost 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 GO Your headphones can have an impedance of 24 to 600 ohms 5 Power Button Functions Power button _ XM4 Headphone DEVICES Amplifier E 2 b e x C T Input 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 CD 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 p
9. nued TT User adjustable from mono to Geze stereo using potentiometer 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 XM4_v35 2007 Berdea DEVICES CORPORATION Practical DEVICES www practicalde
10. resses Toggle LED dimming CrossFeed Controls Crossfeed Enable Switch Crossfeed Adjuster Practical XM4 Headphone DEVICES Amplifier e a Bass y Ze T input The XM4 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 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 c
11. ry should not protrude out of the rear of the unit if it does protrude you won t be able to completely screw down the rear panel Check that the battery cable hasn t prevented the battery from being pushed in completely D 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 XM4 will Gain Boost deliver 13dB of gain Additionally you can Jumpers 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 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 Lithium Battery Charger Lithium Battery FastCharge System If your XM4
12. t 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 nota 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 Practical Devices will refund you the original cost plus the cost of the original shipping Customer must pay for return shipping cost Further
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