Musical Fidelity M250 User's Manual
Contents
1. or coloured green or green and yellow or by the earth symbol alle The wire which is coloured brown must be connected to the terminal which is marked with the letter L or coloured red The wire which is coloured blue must be connected to the terminal which is marked with the letter N or coloured black If connecting to a BS1363 plug a 13 amp fuse must be used WARNING The M250 is a powerful amplifier and must necessarily supply high voltages through the loudspeaker terminals Therefore to avoid any possibility of an electric shock DO NOT TOUCH THE SPEAKER TERMINALS when the unit is being used To comply with BSEN60065 safety regulations the 4mm banana plug holes have been fitted with plastic blanking pieces Removal of these will invalidate any elec trical safety approval of this product WARNING Any modifications to this product not expressly approved by Musical Fidelity who is the party responsible for standards compliance could void the user s authority to operate this equipment Issue 4 May 2002 M250 Amplifier Instructions for Use Page 2 of 8 SSa ee GENERAL ADVICE INSTALLATION PRECAUTIONS and USER INFORMATION Your new M250 power amplifier is designed and built to provide trouble free performance but as with all electronic devices it is necessary to observe a few precautions Heed all warnings shown on the back of the product Only connect the M250 amplifier to a mains outlet having th2. what to look for check the following No power when MAINS Mains plug not inserted Plug in securely POWER switch is operated fully into rear socket No sound Tape monitor function has Switch off tape monitor been selected on the pre at the pre amplifier amplifier Wrong connections between Check audio input lead pre amplifier and the M250 connections Speakers not connected or Check speaker cables incorrectly wired In multi channel use the Speakers are connected out of Ensure speakers are sound is not precise and phase connected correctly lacking bass and stereo image If none of these actions effect a cure please contact your dealer or an authorised Musical Fidelity service agent Remember never open the case of the M250 power amplifier yourself as this will invalidate the guarantee Issue 4 May 2002 M250 Amplifier Instructions for Use Page 7 of 8 SPECIFICATIONS M250 Monobloc Amplifier Output voltage RMS peak Power output Peak to peak output current Damping factor Output devices per channel Total Harmonic Distortion noise Intermodulation distortion Frequency response Audio gain Input impedance Input sensitivity for full power output into 8 Ohms Signal noise ratio reference full power output Input Outputs Power requirements Dimensions Weight Standard accessories 45 Volts 20Hz to 20kHz 127 Volts 250 Watts into 8 Ohms 24dBW 450 Watts into 4 Ohms 72 Amps 18
3. 0 6 0 006 at 1kHz up to 90 power into 4 or 8 Ohms 0 004 at 12 5 Watts into 8 Ohms 20Hz to 20kHz 0dB 10Hz to 100kHz 0 1 5dB 30dB 31 5 times nominal 31K Ohm 1 42 Volts gt 115dB A weighted 1 RCA connector 1 amplifier channel via 2 pairs of speaker binding posts 1 RCA loop output socket 100 115 230V AC 50 60Hz factory preset 1000 Watts maximum into 8 Ohms load 70 Watts idle 192 mm 7 6 inches wide 125 mm 4 9 inches high including feet 460 mm 18 1 inches deep including terminals 12 kg 26 4 Ibs unit only unboxed 14 kg 30 8 lbs in shipping carton IEC type mains lead CE Musical Fidelity reserves the right to make improvements which may result in specification or feature changes without notice Issue 4 May 2002 M250 Amplifier Instructions for Use Page 8 of 8
4. EAKER my OUTPUTS TOMER vE Patan cs ae DN WY oe pasar SERALNUM BER 7 7 sa J TRIGGER 5 TRIGGER Por ee OUT A j IN op a eal ee eS Ze N M efi aa ee J LINE aa INPUT ae POs T ERa POWER CONSUMPTION 400W ass ae y j aes eo A A IMA 50 THIS APPLIANCE MONOBLOC POWER AMPLIFIER MUST T en f i hase TmicianD BY MUSCALFDELRY BE EARTHED ie Mame 2 UNTS15 170DMPT TRADNG ESATE 50 60Hz M PO RIANT yon N RO AD W EM BIEY M DDIESEX HA9 O TF ENG KY D g o 8 7 8 9 10 Issue 4 May 2002 M250 Amplifier Instructions for Use Page 4 of 8 All input output and power connections should be made with the mains power switched OFF INPUT CONNECTIONS As the M250 is a mono power amplifier two are required for stereo operation and further units can be used for multi channel surround systems or bi amplification etc The M250 can be used with a preamplifier or any audio line level source which has a volume control Connect your pre amplifier or other line level source to the RCA socket on the back panel marked LINE INPUT For the best results we recommend either Musical Fidelity X LINX no nonsense cables for this connection or the highly rated Nu Vista leads with integral RFI suppression Various lengths are available in the Nu Vista interconnect range Please contact your local dealer for more infor mation BI AMPLIFICATION The M250 has a LOOP
5. M250 MONOBLOC AMPLIFIER NAZDO MUSCALFDELIY INSTRUCTIONS FOR USE Thank you for purchasing the Musical Fidelity M250 monobloc power amplifier Used properly and carefully it should give you many years of outstanding musical reproduction Dust regularly with a soft duster or soft brush but be careful when using cleaning or polishing agents they may harm the surface finish If you have any questions about your audio system please consult your dealer who is there to help and advise MUSICAL FIDELITY Issue 4 May 2002 M250 Amplifier Instructions for Use Page I of 8 C O SAFETY INFORMATION IMPORTANT U K only This unit is supplied in the U K with a mains lead fitted with a moulded 13 amp plug If for any reason you need to cut off this plug please remove the fuse holder and dispose of the plug safely out of reach of children Jt must not be plugged into a mains outlet The wires in the mains lead supplied with this appliance are coloured in accordance with the following code Green and yellow Earth IG cael ena ii Neutral BLOW ih iici veces Live WARNING This appliance must be earthed As the colours of the wires of the mains lead of this appliance may not correspond with the coloured markings identifying the terminals in your plug proceed as follows The wire which is coloured green and yellow must be connected to the terminal in the plug which is marked with the letter E
6. OUTPUT socket to allow bi amping of a speaker with suitable active or passive crossover net works This socket is directly linked inside the amplifier to the LINE INPUT socket to enable onward connection to a further unit such as another M250 In this arrangement typically one M250 is used to drive the tweeter high frequen cies and one to drive the woofer low frequencies of each loudspeaker enclo sure Thus four M250s would be needed for a stereo pair Issue 4 May 2002 M250 Amplifier CONNECTIONS Taking the left channel connections the pre amp s left output is connected to the first M250 s LINE INPUT used for the woofer or low frequencies and then the first M250 s LOOP OUTPUT is connect ed to the LINE INPUT of the second M250 used for the tweeter or high fre quencies Repeat this process for the right channel If you are in any doubt about bi amping please contact your dealer who will be able to advise TRIGGER CONNECTIONS Two 3 5mm jack sockets on the rear panel marked TRIGGER IN and TRIGGER OUT are provided for electronically switching the audio sense mode see page 6 These are directly linked together inside the amplifier to enable onward con nection to a further unit such as another M250 OUTPUT CONNECTIONS Connect your loudspeaker to the terminals marked SPEAKER OUTPUTS Two sets are provided for parallel opera tion or bi wiring but note tha
7. aning or polishing agents they may harm the surface finish The electronics in modern hi fi equipment is complex and may therefore be adversely affected or damaged by lightning For protection of your audio system during electrical storms remove the mains plugs and disconnect any aerial lead If after sales service is required to help your dealer identify the M250 please quote the serial number located on the rear panel of the unit RADIO FREQUENCY INTERFERENCE R FI This product has been tested to ensure that its operation is not adversely affected by normal background levels of R F I and that it does not itself generate excessive amounts of interfer ence However if a problem persists please contact your Musical Fidelity agent Issue 4 May 2002 M250 Amplifier Instructions for Use Page 3 of 8 E CONNECTIONS AND FACILITIES A A W A O PERATE POW ER S 1 3 N M MUSCALFDELIY ALFDELIY eo io Front panel layout OPERATE indicator LED blue Power status button see page 6 POWER on indicator LED orange Back panel layout Speaker output see page 5 Trigger output see pages 5 and 6 Speaker output see page 5 Audio loop output see page 5 Power switch Audio line input IEC type mains inlet socket Trigger input see pages 5 and 6 3 4 5 6 if f ey meae 7 SP
8. e same voltage as marked at the back of the unit Always ensure that when disconnecting and reconnecting your audio equipment the mains supply is switched off Position the mains lead and signal interconnects where they are not likely to be walked on or trapped by items placed on them Do not use near water or place water filled containers on the amplifier for example flower vases or potted plants If water does spill into the player immediately pull out the mains plug from the wall socket and inform your dealer who should then check the unit before further use Entry of liquid into the amplifier is dangerous and may cause electric shock or fire hazard Do not place the unit near heat sources such as radiators direct sunlight or other equipment The case of this amplifier can run at high temperatures operate the unit in a well ventilated area and do not touch the side heatsink fins after periods of use at high output power Do not remove covers or try to gain access to the inside There are no internal user adjust ments Refer all service work to an authorised Musical Fidelity agent NOTE Unauthorised opening of the equipment will invalidate any warranty claims There are fuses inside the M250 Amplifier In the unlikely event that one blows refer the unit to your audio dealer Do NOT try to replace the fuse yourself as this will invalidate the warranty Dust regularly with a soft duster or soft brush but be careful when using cle
9. fier OPERATION Trigger Mode The M250 responds to a trigger on con trol voltage of between 5 and 12 volts posi tive or negative received via the 3 5mm TRIGGER IN socket on the rear panel The first trigger pulse received after apply ing mains power will turn the amplifier on and cancel the audio sense mode When the amplifier senses a trigger off pulse return to zero voltage the amplifier will turn off The M250 may be turned on or off manual ly with the front panel button at any time When the amplifier has been turned on manually by the button it will turn off if it receives a trigger on signal followed by a trigger off pulse If the amplifier has been turned off manual ly by the button it will turn on if it receives a trigger off signal followed by a trigger on pulse To cancel trigger mode and revert to audio sense mode first remove the trigger source Then using the mains switch at the rear of the unit turn mains power off and after a few seconds back on again Audio Adjustment Select the required audio input source on your pre amplifier and advance the volume control to obtain the preferred sound level Instructions for Use Page 6 of 8 EA TROUBLESHOOTING Basic problem solving with an amplifier is similar to troubleshooting any other electrical or electronic equipment Always check the most obvious possible causes first To give you a few ideas of
10. t the combined load impedance must not be less than 4 ohms BEFORE SWITCHING ON Plug the accessory IEC mains lead into the rear panel socket then the other end into a wall outlet Turn the volume control on your preampli fier to minimum and switch on its power Instructions for Use Page 5 of 8 OPERATION Press the POWER rocker switch on the rear panel the orange POWER LED on the front panel will light confirming that the unit is ready for use Audio Sense Mode The M250 is now in audio sense mode and will turn on when an input signal is detected When an audio signal is received the amplifier will turn on and the blue OPER ATE LED will be lit If there has been no audio input for about 15 minutes the amplifier will turn off and the OPERATE LED will go out The M250 may be turned on or off manu ally by pressing the power status button on the front panel When the amplifier has been turned on manually by the front button it will revert to audio sense mode if there has been no audio input for about 15 minutes When the amplifier has been turned off manually by the button it will stay off even if audio input is present until there has been no audio for about 15 minutes when it will revert to audio sense mode If there is an audio input signal present when mains power is applied to the M250 it will turn on immediately with the OPERATE LED lit Issue 4 May 2002 M250 Ampli
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