Radio Shack MPA-125 Owner's Manual - Features

Manual is about: 100-Watt PA Amplifier

Summary of MPA-125

  • Page 1

    Owner’s manual please rea d before usin g thi s e quip m e n t. Mpa-125 100-watt pa amplifier 32-2003.Fm page 1 tuesday, march 28, 2000 10:45 am.

  • Page 2: Contents

    2 ˆ contents features .................................................................................................................................. 3 preparation ............................................................................................................................. 4 prese...

  • Page 3: Features

    3 features ˆ features your radioshack mpa-125 100-watt pa amplifier gives you the versatility and power you need in a professional sound system. Its wide frequency response easily handles am- plification of voice and music. Use it in meet- ing halls and auditoriums, at sports events, in schools, and...

  • Page 4: Preparation

    4 preparation ˆ preparation presetting the controls before you begin making connections or using your amplifier, preset the audio input source’s and the amplifier’s controls to avoid over-driving a channel or producing sudden unexpected loud sounds. Presetting audio input devices set the audio input...

  • Page 5: Connections

    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 hea...

  • Page 6

    6 connections notes: • if your microphone’s cord is longer than 20 feet (6.01 meters), we recommend that you connect it to a balanced jack to reduce signal hum. • if you connect a microphone to both jacks for mic 1 , mic 2 , mic 3 , or mic 4 , the microphone you connect to the unbalanced jack has pr...

  • Page 7

    7 connections connecting an auxiliary sound source you can connect any high-level sound source, such as a cd player, tape deck, or tuner, to the cd/aux jack on the back of the amplifier. Connecting the mix bus jack you can connect another mpa-125 to this jack to double the size of your pa system. Th...

  • Page 8

    8 connections connecting the speakers you can connect one or more 4-, 8- or 16- ohm speakers to the amplifier, with or with- out transformers. To ensure equal volume from each speaker, all connected speakers should have the same impedance rating. Proper phasing is important when you use more than on...

  • Page 9

    9 connections you can achieve a proper total impedance by combining series and parallel connec- tions. Preparing the speaker wire use the shortest length of wire possible to connect the speakers. After placing the speakers, use this table to determine the wire length and choose the appropriate gauge...

  • Page 10

    10 connections connecting two speakers in parallel follow these steps to connect speakers in parallel. 1. Connect both speaker’s negative (–) terminals to each other, then connect both wires to the com terminal on the back of the amplifier. 2. Connect both speaker’s positive (+) terminals to each ot...

  • Page 11

    11 connections 3. Connect the two pairs of speakers in parallel. If you connected 8 ohm speak- ers the total impedance of both pairs is 8 ohms (16 ÷ 2 = 8). Note: if each of the four speakers is 8 ohms, the total speaker impedance of the combined series/parallel connection described above is also 8 ...

  • Page 12

    12 connections follow these steps to connect speakers using a transformer. Connect a wire from 70v rms on the back of the amplifier to the transformer’s desired pri- mary tap (10, 5, 2.5, 1.25 or 0.62 watts). Note: usually, each speaker in a system uses the same wattage tap. If you want a particular...

  • Page 13

    13 connections safety indicators your amplifier has two indicators that warn you of potential damage to the amplifier. The clipping indicator lights when a sound source’s signal exceeds its mixing control setting. If this happens, reduce the level of the appropriate mixing control or reduce master v...

  • Page 14

    14 connections using the feedback filter the feedback filter control lets you reduce or eliminate squeal and other noise caused by feedback. After you adjust master volume , mic 1 , mic 2 , mic 3 , mic 4/phono , and cd/aux , turn on the amplifier and any connected sound source. If you hear any feedb...

  • Page 15: Troubleshooting

    15 troubleshooting ˆ troubleshooting we do not expect you to have any problems with your radioshack mpa-125 100-watt pa am- plifier, but if you do have a problem, this chart might help. If not, take the amplifier to your local radioshack store for assistance. Symptom possible cause suggestion no pow...

  • Page 16: Care and Maintenance

    16 care and maintenance ˆ care and maintenance your radioshack mpa-125 100-watt pa amplifier is an example of superior design and craftsmanship. The following suggestions will help you care for your amplifier so you can en- joy it for years. Keep the amplifier dry. If it gets wet, wipe it dry immedi...

  • Page 17

    17 care and maintenance replacing the fuse if the amplifier does not operate, you might need to replace the fuse on the back of the amplifier with the supplied (or another) 3- amp, 250-volt fuse. Important: let the amplifier cool down and see if it starts again before you assume a fuse needs to be r...

  • Page 18: Specifications

    18 specifications ˆ specifications output power at thd 2%, 8 ohm load 1 khz ................................................................................... 100 w total harmonic distortion (at 70 watts, 8 ohms, 1 khz, with band pass filter) mic (phone jack) ..........................................

  • Page 19: Notes

    19 notes ˆ notes 32-2003.Fm page 19 tuesday, march 28, 2000 10:45 am.

  • Page 20

    32-2003 03a00 printed in china radioshack a division of tandy corporation fort worth, texas 76102 limited one-year warranty this product is warranted by radioshack against manufacturing defects in material and workman- ship under normal use for one (1) year from the date of purchase from radioshack ...