Radio Shack MPA-125 Owner'S Manual Download Page 5

5

Connections

MOUNTING THE AMPLIFIER

You can mount the amplifier in a standard-
sized audio equipment rack or on a desk,
shelf, or table. Be sure you place it in a loca-
tion with adequate ventilation. Do not put it
on thick carpeting (which can restrict air flow)
or near a heat source such as a heat vent or
radiator (which can cause it to overheat).

PLACING THE SPEAKERS

Speaker placement depends on your room’s
size and arrangement. We recommend you
play a wide-range recording and experiment
with speaker placement until you find the lo-
cations that result in the best sound. For the
best results, point the speakers in toward the
listeners, especially if you place speakers far
apart so their coverage areas overlap to pre-
vent dead spots (areas not covered by the
speakers’ sound). Position the speakers
slightly above the level of the listeners’
heads (see “Connecting the Speakers” on
Page 8).

ˆ

Connections

CONNECTING INPUT SOURCES

You can connect optional components such as microphones, a tuner, a turntable, or a CD play-
er to your amplifier to expand your audio system. To prevent hum and other noise, use low-ca-
pacitance shielded cable. Your local RadioShack store carries a wide selection of audio
components and cable.

Before you make any connections, be sure 

POWER

 on the front of the amplifier is out and the

AC power cord is not plugged in.

Connecting Microphones

You can connect up to four high- or low-impedance microphones to the microphone inputs on
the back of the amplifier. Each input (labeled 

MIC 1

MIC 2

MIC 3

, and 

MIC 4

) has a balanced

and unbalanced jack. You need a microphone cord with a 

1

/

4

-inch (6.35-mm) plug to connect to

an unbalanced jack or a microphone cord with a 3-pin XLR plug to connect to a balanced jack.

MIC 1

MIC 4   MIC 3  MIC 2

MIC 4  MIC 3  MIC 2 

MIC 1 

3-Pin XLR Plug

1/4

 -Inch Plug

32-2003.fm  Page 5  Tuesday, March 28, 2000  10:45 AM

Summary of Contents for MPA-125

Page 1: ...Owner s Manual Please read before using this equipment MPA 125 100 Watt PA Amplifier 32 2003 fm Page 1 Tuesday March 28 2000 10 45 AM...

Page 2: ...Connecting Only One Speaker 9 Connecting Two Speakers In Series 9 Connecting Two Speakers In Parallel 10 Connecting Four Speakers In Series Parallel Combination 10 Connecting Speakers with Transforme...

Page 3: ...ources for music and special effects Phones Jack you can connect head phones so you can hear the mixed audio in privacy Master Volume Control lets you adjust the overall sound level EQ IN OUT Switch l...

Page 4: ...prevent possible hearing loss set the amplifier s controls to the settings shown below After you turn on the amplifier or change the program source adjust the controls to a comfortable listening leve...

Page 5: ...of the listeners heads see Connecting the Speakers on Page 8 Connections CONNECTING INPUT SOURCES You can connect optional components such as microphones a tuner a turntable or a CD play er to your am...

Page 6: ...set PHONO MIC 4 on the back of the amplifier to MIC 4 Connecting a Turntable You can connect a low level audio input source such as a magnetic cartridge turntable to the L PHONO and R PHONO jacks on t...

Page 7: ...phones and two turntables and two auxiliary sound sources Use a shielded cable with phono plugs at each end and connect the cable between the MIX BUS jacks on the back of the two amplifiers For the be...

Page 8: ...ries when the first speaker s positive terminal is connected to the next speaker s nega tive terminal Determine the total impedance of speakers you want to connect in series by adding up the individua...

Page 9: ...nnector you want insert the end of the wire into the terminal s hole then release the lever to secure the wire Connecting Only One Speaker Connect the speaker s negative terminal to COM common on the...

Page 10: ...erminal 4 8 or 16 on the back of the amplifier that matches the total speaker impedance Connecting Four Speakers In Series Parallel Combination Follow these steps to combine series and parallel connec...

Page 11: ...tem use a line transformer not supplied for each speaker Transformers offer these advantages You can connect speakers with different impedances without causing differ ences in output between the speak...

Page 12: ...the transformer s secondary side CONNECTING POWER To connect the amplifier to power plug its power cord into a standard AC outlet Your amplifier s fuse located on the amplifi er s back panel protects...

Page 13: ...a pair of mono or stereo headphones not supplied with a 1 4 inch 6 35 mm plug into the PHONES jack on the front of the amplifier Using headphones lets you easily check and adjust the sound source s ba...

Page 14: ...turn on the amplifier and any connected sound source If you hear any feedback turn FEEDBACK FILTER clockwise until you reduce or eliminate the feedback Note The FEEDBACK FILTER control decreases feedb...

Page 15: ...one or cable might be faulty Check all microphones and cables The speaker s wiring might be shorted Check all connections The speakers might be the wrong impedance Make sure all connected speakers hav...

Page 16: ...vices and distort or melt plastic parts Keep the amplifier away from dust and dirt which can cause premature wear of parts Handle the amplifier gently and carefully Dropping it can damage circuit boar...

Page 17: ...ck of the ampli fier then pull out the cap to remove the fuse 3 If the fuse is blown replace it 4 Insert the fuse into the fuse holder s socket press the fuse holder back into the amplifier then use a...

Page 18: ...0 dB MIC XLR Jack 54 dB CD AUX 73 dB PHONO 60 dB Frequency Response at 1 Watt 3 dB MIC Phone Jack 60 Hz 20 kHz MIC XLR Jack 60 Hz 20 kHz CD AUX 60 Hz 20 kHz PHONO RIAA 100 Hz 10 kHz 12 dB 12 5 dB Notc...

Page 19: ...19 Notes Notes 32 2003 fm Page 19 Tuesday March 28 2000 10 45 AM...

Page 20: ...during the warranty period take the product and the RadioShack sales receipt as proof of purchase date to any RadioShack store RadioShack will at its option un less otherwise provided by law a correc...

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