Radio Shack Stereo Amplifier MPA 125 User Guide

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MPA-125 100-Watt PA Amplifier  
 
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ˆ Features  
Master Volume Control  
the overall sound level.  
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 in the office for paging systems  
– anywhere you need to deliver special an-  
nouncements with excellent sound.  
— lets you adjust  
EQ IN/OUT Switch  
— lets you connect and  
use an equalizer with the amplifier.  
Push-Terminal Connectors  
ly connect wires directly to the amplifier.  
— let you easi-  
Five Individual Source Mixing Controls  
let you mix connected sound sources individ-  
ually or all at the same time.  
Your amplifier includes these features:  
100-Watt Output  
output for many types of sound installations.  
— provides powerful audio  
Feedback Filter  
feedback.  
— lets you control audio  
60–25000 Hz Frequency Response  
vides wide-ranging response for true audio  
reproduction.  
— pro-  
Read this manual carefully. It describes vari-  
ous speaker connections to help you select  
the best arrangement for your amplifier and  
connected equipment, and explains how to  
use the amplifier.  
Lighted VU Meter  
— measures the amplifi-  
er’s output in decibels.  
Two Mounting Options  
the amplifier in a standard-sized audio equip-  
ment rack or on a desk, shelf, or table.  
— you can mount  
WARNING:  
ard, do not expose this product to rain or moisture.  
To reduce the risk of fire or shock haz-  
Clipping Indicator  
— lights when a sound  
CAUTION  
source signal exceeds its mixing control set-  
ting.  
RISK OF ELECTRIC SHOCK.  
!
DO NOT OPEN.  
CAUTION:  
TO REDUCE THE RISK OF  
Overload Protection  
— automatically inter-  
ELECTRIC SHOCK, DO NOT REMOVE  
COVER OR BACK. NO USER-SERVICEABLE  
PARTS INSIDE. REFER SERVICING TO  
QUALIFIED PERSONNEL.  
rupts the amplifier’s power and lights an indi-  
cator if the amplifier gets too hot due to  
power overload.  
Four Microphone Input Jacks  
connect up to four balanced or unbalanced  
microphones to the amplifier.  
— you can  
This symbol is intended to alert you to  
the presence of uninsulated danger-  
ous voltage within the product’s enclo-  
sure that might be of sufficient  
magnitude to constitute a risk of elec-  
tric shock. Do not open the product’s  
case.  
CD/Auxiliary Input Jack  
— you can connect  
a variety of audio input sources for music  
and special effects.  
This symbol is intended to inform you  
that important operating and mainte-  
nance instructions are included in the  
Phones Jack  
phones so you can hear the mixed audio in  
privacy.  
— you can connect head-  
!
literature accompanying this product.  
3
Features  
 
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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 sources’ controls to these levels:  
Audio Device  
Control  
Setting  
Turntable  
Tape Deck  
Power  
Power  
Off  
Off  
CD Player  
Power  
Off  
Amplifier/Receiver  
Power Tone  
Off Flat  
Presetting the Amplifier  
Warning:  
To 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 level.  
Set the amplifier’s controls to these levels:  
Control  
POWER  
Setting  
Out  
MIN  
MIN  
MIC 1 MIC 2 MIC 3 MIC 4/PHONO CD AUX  
,
,
,
,
MASTER VOLUME  
MIC 1  
MIC 3  
MIC 2  
MIC 4/PHONO  
MASTER VOLUME  
POWER  
CD/AUX  
4
Preparation  
 
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MOUNTING THE AMPLIFIER  
PLACING THE SPEAKERS  
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).  
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.  
POWER  
Before you make any connections, be sure  
AC power cord is not plugged in.  
on the front of the amplifier is out and the  
Connecting Microphones  
You can connect up to four high- or low-impedance microphones to the microphone inputs on  
MIC 1 MIC 2 MIC 3  
MIC 4  
) has a balanced  
the back of the amplifier. Each input (labeled  
,
,
, and  
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.  
1
/
4
-Inch Plug  
MIC 4  
MIC 3 MIC 2  
MIC 1  
3-Pin XLR Plug  
MIC 4 MIC 3 MIC 2  
MIC 1  
5
Connections  
 
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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.  
MIC 1 MIC 2 MIC 3  
MIC 4  
, the microphone  
• If you connect a microphone to both jacks for  
,
,
, or  
you connect to the unbalanced jack has priority.  
MIC 4  
PHONO/MIC 4  
on the back of the  
• If you connect a microphone to either  
jack, set  
MIC 4  
amplifier to  
.
Connecting a Turntable  
Turntable  
GND  
PHONE/MIC 4  
You can connect a low-level audio input source (such as a magnetic cartridge turntable) to the  
L PHONO  
R PHONO  
jacks on the back of the amplifier.  
and  
PHONO  
PHONO/MIC 4  
on the back  
If you connect a low-level audio input source to the  
jacks, set  
PHONO  
of the amplifier to  
.
To avoid a low-frequency hum, connect your turntable’s ground wire (usually black or green) to  
GND  
the amplifier’s  
terminal.  
6
Connections  
 
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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.  
CD/AUX  
Connecting the MIX BUS Jack  
You can connect another MPA-125 to this jack to double the size of your PA system. This lets  
you use up to eight microphones (or six microphones and two turntables), and two auxiliary  
sound sources.  
MIX  
Use a shielded cable with phono plugs at each end, and connect the cable between the  
BUS  
jacks on the back of the two amplifiers. For the best results, do not use a cable longer than  
6 feet.  
MIX BUS Jack  
Connecting an Equalizer  
EQ IN  
EQ OUT  
jacks  
You can connect an equalizer or other external signal processor to the  
on the back of the amplifier.  
and  
EQ IN/OUT  
Note:  
EQ OUT  
jack for recording.  
You can also connect a tape deck to the  
7
Connections  
 
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Determine the total impedance of  
speakers you want to connect in series  
by adding up the individual impedances  
of all the connected speakers. For  
example, if you want to connect two 8-  
ohm speakers in series, add 8 (the  
impedance of one speaker) plus 8 (the  
impedance of the other speaker) for a  
total speaker impedance of 16 ohms  
(see “Connecting Two Speakers In  
Series” on Page 9).  
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 one speaker in the same room or  
area. Out-of-phase speakers can lose up to  
one-half of their potential volume, and can  
have a significantly decreased bass effect.  
• Speakers are connected in parallel  
when all the speakers’ negative termi-  
nals are connected together and all their  
positive terminals are connected  
together.  
Most speaker terminals are color-coded or  
have a mark that indicates the terminal’s po-  
larity. Usually, terminals with positive polarity  
are red or have a plus symbol (+), and termi-  
nals with negative polarity are black or have  
a minus symbol (–). Phasing is correct when  
you connect + to + and – to –.  
Determine the total impedance of  
speakers you want to connect in parallel  
by dividing the impedance of one  
speaker by the number of speakers. For  
example, if you plan to connect two 8-  
ohm speakers in parallel, divide 8 (the  
impedance of one speaker) by 2 (the  
number of speakers) for a total speaker  
impedance of 4 ohms (see “Connecting  
Two Speakers In Parallel” on Page 10).  
Determining Total Speaker  
Impedance  
Before you connect speakers to the amplifi-  
er, you must determine the total speaker im-  
pedance.  
• If you are connecting more than two  
speakers using only series or only paral-  
lel connections, the total impedance  
might exceed the amplifier’s maximum  
impedance (16 ohms) or fall below its  
minimum impedance (4 ohms).  
Caution:  
A total speaker impedance higher  
than 16 ohms or lower than 4 ohms can  
damage your amplifier or speakers.  
In determining the total speaker impedance,  
you must first determine if you are connect-  
ing the speakers in series, parallel, or a se-  
ries/parallel combination.  
For example, if you connect four 8-ohm  
speakers:  
• In series, the total impedance is 32  
ohms (8 + 8 + 8 + 8 = 32). This  
exceeds the maximum rating.  
Note:  
For the best results when connecting  
speakers (in series or parallel), only use  
speakers that have the same impedance.  
• In parallel, the total impedance is 2  
ohms (8 divided by 4 = 2). This falls  
below the minimum rating.  
• Speakers are connected in series when  
the first speaker’s positive terminal is  
connected to the next speaker’s nega-  
tive terminal.  
8
Connections  
 
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You can achieve a proper total impedance  
by combining series and parallel connec-  
tions.  
Connecting Only One Speaker  
Connect the speaker’s negative (–) terminal  
COM  
to  
(common) on the back of the amplifi-  
er. Then connect the speaker’s positive (+)  
Preparing the Speaker Wire  
4
8
terminal to the speaker terminal ( , , or  
16  
) on the back of the amplifier that match-  
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 size:  
es the speaker’s impedance.  
Wire Length  
Wire Gauge  
25 feet or less  
Over 25 feet  
18 gauge  
16 gauge  
8
Speaker  
Note:  
If you connect speakers without trans-  
formers, the speaker wire should be no long-  
er than 50 feet (see “Connecting Speakers  
with Transformers” on Page 11).  
Connecting Two Speakers In  
Series  
Follow these steps to connect speakers in  
series.  
To prepare the speaker wire, remove about 1  
inch of insulation from the end of the speaker  
wire you are connecting to the amplifier.  
Then twist the exposed wire to secure all of  
the wire strands.  
To connect speaker wire to the amplifier,  
press the push terminal lever on the amplifier  
for the connector you want, insert the end of  
the wire into the terminal’s hole, then release  
the lever to secure the wire.  
Left Speaker  
Right Speaker  
1. Connect the left speaker’s positive (+)  
terminal to the right speaker’s negative  
(–) terminal.  
2. Connect the left speaker’s negative (–)  
Terminal Levers  
terminal to  
amplifier.  
COM  
on the back of the  
3. Connect the right speaker’s positive (+)  
4
terminals to the speaker terminal ( ,  
16  
8
, or ) on the back of the amplifier  
that matches the total speaker imped-  
ance.  
9
Connections  
 
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Connecting Two Speakers In Parallel  
Follow these steps to connect speakers in parallel.  
Two 8 Speakers  
8
___________  
2 Speakers  
= 4  
8
8
Speaker 1  
Speaker 2  
1. Connect both speaker’s negative (–) terminals to each other, then connect both wires to  
COM  
the  
terminal on the back of the amplifier.  
2. Connect both speaker’s positive (+) terminals to each other, then connect both wires to the  
4
8
16  
speaker terminal ( , , or ) 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 connections.  
8
8
of 1 Pair  
No. of Pairs  
= Total  
16W  
2
8
8
= 8  
1. Group the four speakers into two pairs.  
2. Connect each pair of speakers in series. If you connected 8-ohm speakers, the total  
impedance of each pair is 16 ohms (8 + 8 = 16).  
10  
Connections  
 
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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).  
Line transformers have several connectors  
called taps.  
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 ohms. Like-  
wise, the total speaker impedance is 4  
or 16 ohms if the speakers are 4 or 16  
ohms, respectively.  
Taps  
4. Connect the speakers’ negative (–) ter-  
The primary taps (on one side of the trans-  
former) are the inputs and are rated in watts.  
The secondary taps (on the opposite side of  
the transformer) are the outputs and are rat-  
ed in ohms.  
COM  
minals to the  
of the amplifier.  
terminal on the back  
5. Connect the speaker’s positive (+) ter-  
4
8
minals to the speaker terminal ( , ,  
16  
or ) on the back of the amplifier that  
matches the total speaker impedance as  
calculated in Step 3.  
Primary  
Taps  
Secondary  
Taps  
Connecting Speakers with Trans-  
formers  
For the best results when you connect two or  
more speakers to your system, use a line  
transformer (not supplied) for each speaker.  
Cautions:  
Transformers offer these advantages:  
• Before you connect the speakers, be  
sure the total wattage of the primary tap  
you intend to use does not exceed the  
amplifier’s maximum 100-watt output  
power rating.  
You can connect speakers with different  
impedances without causing differ-  
ences in output between the speakers.  
You can add or remove a speaker from  
the system without having to recalculate  
the entire system’s impedance.  
70V  
• Avoid multiple connections to the  
RMS  
COM  
terminals on the back of  
and  
the amplifier.  
You can reduce signal loss when you  
use speaker wire over 50 feet long.  
11  
Connections  
 
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Follow these steps to connect speakers using a transformer.  
70V RMS  
Connect a wire from  
on the back of  
USING YOUR AMPLIFIER  
the amplifier to the transformer’s desired pri-  
mary tap (10, 5, 2.5, 1.25 or 0.62 watts).  
POWER  
Press in  
to turn on the amplifier.  
Start the input sound source.  
Note:  
Usually, each speaker in a system  
uses the same wattage tap. If you want a  
particular speaker to have a higher volume  
MASTER VOLUME  
Rotate  
to its mid-position.  
70V RMS  
level, connect the wire from  
to a  
MIC 1 MIC 2 MIC 3 MIC  
One at a time, adjust  
4/PHONO  
, and  
and balance.  
,
,
,
higher wattage tap on the transformer.  
CD/AUX  
to the desired volume  
COM  
Connect a wire from  
on the back of the  
C
amplifier to the  
(common) taps on the  
Note:  
these controls, turn  
If you hear feedback after you adjust  
transformer’s primary side.  
FEEDBACK FILTER  
clock-  
wise until the noise disappears (see “Using  
the Feedback Filter” on Page 14).  
Connect a wire from the speaker’s positive  
(+) terminal to the transformer’s secondary  
tap that matches the speaker’s total imped-  
ance (4 ohms, 8 ohms, or 16 ohms).  
After you get the desired balance, adjust  
MASTER VOLUME  
to the desired volume lev-  
el.  
Connect a wire from the speaker’s negative  
C
(–) terminal to the  
(common) tap on 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 the amplifier from  
voltage surges. If the PROTECTION indica-  
POWER  
tor does not light when you press  
(see “Using Your Amplifier” and “Safety Indi-  
cators” on Page 13), check the fuse. If it is  
blown, see “Replacing the Fuse” on Page 17.  
12  
Connections  
 
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SAFETY INDICATORS  
Your amplifier has two indicators that warn you of potential damage to the amplifier.  
CLIPPING Indicator  
PROTECTION Indicator  
The CLIPPING indicator lights when a sound source’s signal exceeds its mixing control setting.  
MASTER VOLUME  
If this happens, reduce the level of the appropriate mixing control or reduce  
until the indicator flickers only at peak volume levels.  
The PROTECTION indicator lights if the amplifier gets too hot because of a power overload.  
The amplifier’s built-in protection circuit temporarily interrupts the amplifier’s power. If this hap-  
POWER  
pens, press  
to turn off the amplifier, let the amplifier cool for about 15 minutes, and cor-  
POWER  
rect whatever caused the overload. Then press  
again to turn on the amplifier.  
Note:  
If the power does not immediately come on, turn off the power again, wait about 5 more  
POWER  
minutes, then press  
again.  
• Do not listen at extremely high volume  
levels. Extended high-volume listening  
can lead to permanent hearing loss.  
MONITORING THE SOUND  
SOURCES  
To monitor the sound sources, plug a pair of  
mono or stereo headphones (not supplied)  
with a 1/4-inch (6.35-mm) plug into the  
• Once you set the volume, do not  
increase it. Over time, your ears adapt  
to the volume level, so a volume level  
that does not cause discomfort might  
still damage your hearing.  
PHONES  
jack on the front of the amplifier.  
Using headphones lets you easily check and  
adjust the sound source’s balance. Your lo-  
cal RadioShack store carries a wide selec-  
tion of headphones.  
USING AN EQUALIZER  
EQ/BY-  
If you connected an equalizer, set  
Listening Safely  
PASS  
EQ  
.
on the back of the amplifier to  
To protect your hearing, follow these guide-  
lines when you use headphones.  
Note:  
If the equalizer has a bypass switch,  
be sure it is set to OUT or turned off. Other-  
wise, the equalizer has no effect on your sys-  
tem’s sound.  
• Set the volume to the lowest setting  
before you begin listening. After you  
begin listening, adjust the volume to a  
comfortable level.  
13  
Connections  
 
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USING THE FEEDBACK FILTER  
FEEDBACK FILTER  
The  
control lets you reduce or eliminate squeal and other noise caused by  
feedback.  
MASTER VOLUME MIC 1 MIC 2 MIC 3 MIC 4/PHONO  
CD/AUX  
, turn on the  
After you adjust  
,
,
,
,
, and  
FEEDBACK FILTER  
amplifier and any connected sound source. If you hear any feedback, turn  
clockwise until you reduce or eliminate the feedback.  
Note:  
FEEDBACK FILTER  
control decreases feedback frequencies by up to 12 dB. If it does  
The  
not eliminate the feedback, try using a frequency equalizer to further decrease the feedback  
frequencies.  
FEEDBACK FILTER  
14  
Connections  
 
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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  
No power.  
Possible Cause  
Suggestion  
The fuse might be blown.  
Check the amplifier’s fuse and replace it  
if necessary (see “Replacing the Fuse”  
on Page 17).  
Sound source or speakers not con-  
nected correctly.  
Check all connections.  
MASTER VOLUME MIC 1  
MASTER VOLUME MIC 1 MIC  
No sound.  
Amplifier’s  
,
,
Adjust  
,
,
,
MIC 2 MIC 3 MIC 4/PHONO  
CD/  
2 MIC 3 MIC 4/PHONO  
CD/AUX  
,
,
, or  
,
, and  
.
AUX  
controls set to minimum.  
Sound source or speakers not con-  
nected correctly.  
Check all connections.  
A microphone 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 have  
the same impedance rating (see “Con-  
necting the Speakers” on Page 8).  
The speaker’s wires might be too  
small.  
Make sure the speaker’s wires are 18-  
gauge (for wire lengths up to 25 feet) or  
16-gauge (for lengths over 25 feet). For  
the best results, use the shortest length  
of speaker wire possible.  
The amplifier might have shut down.  
Turn the amplifier off and let it cool.  
Make sure the amplifier is properly venti-  
lated, then turn it back on.  
FEEDBACK FILTER  
adjustment.  
Feedback.  
might need  
Turn the amplifier off and let it cool.  
Make sure the amplifier is properly venti-  
lated, then turn it back on.  
Microphones or speakers are too close Reposition the microphones and speak-  
together. ers.  
15  
Troubleshooting  
 
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ˆ Care and Maintenance  
Your RadioShack  
is an example of superior design and  
MPA-125 100-Watt PA Amplifier  
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 immediately. Liquids might con-  
tain minerals that can corrode the electronic circuits.  
Use and store the amplifier only in normal temperature environments. Temper-  
ature extremes can shorten the life of electronic devices 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 boards  
and cases and can cause the amplifier to work improperly.  
Wipe the amplifier with a damp cloth occasionally to keep it looking new. Do not  
use harsh chemicals, cleaning solvents, or strong detergents to clean the am-  
plifier.  
Modifying or tampering with the amplifier’s internal components can cause a malfunction and  
might invalidate its warranty. If your amplifier is not performing as it should, take it to your lo-  
cal RadioShack store for assistance.  
16  
Care and Maintenance  
 
32-2003.fm Page 17 Tuesday, March 28, 2000 10:45 AM  
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 replaced.  
Caution:  
Do not use a fuse with ratings other  
than those specified. Doing so might damage  
your amplifier.  
1. Unplug the amplifier.  
2. Use a Phillips screwdriver to remove the  
fuse holder cap on the back 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 Phillips screw-  
driver to replace the fuse holder cap.  
THE FCC WANTS YOU TO  
KNOW  
Your amplifier might cause TV or radio inter-  
ference even when it is operating properly.  
To determine whether your amplifier is caus-  
ing the interference, turn off your amplifier. If  
the interference goes away, your amplifier is  
causing it. Try to eliminate the interference  
by:  
• moving your amplifier away from the  
receiver  
• contacting your local RadioShack store  
for help  
17  
Care and Maintenance  
 
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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) ....................................................................................................................... 0.25%  
MIC (XLR Jack) .......................................................................................................................... 0.35%  
CD/AUX ...................................................................................................................................... 0.20%  
PHONO ...................................................................................................................................... 0.25%  
Input Sensitivity (at 2% THD, 1 kHz)  
MIC (Phone Jack) .................................................................................................................... 1.35 mV  
MIC (XLR Jack) ............................................................................................................................ 1 mV  
CD/AUX .................................................................................................................................... 150 mV  
PHONO ..................................................................................................................................... 2.8 mV  
Signal to Noise Ratio (Input Shorted) with WTD  
MIC (Phone Jack) ........................................................................................................................ 60 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  
Notch Filter Effect  
Range ............................................................................................................................. 300 Hz–3 kHz  
Depth ......................................................................................................................................... –12 dB  
Noise Level (Input Short) ................................................................................................................. 0.75 mV  
Power Requirements ........................................................................................................... 120V AC 60 Hz  
Dimensions (HWD) ....................................................................................... 43/16 × 1815/16 × 1115/16 Inches  
(10.0 × 48.2 × 27.3 cm)  
Weight .............................................................................................................................................. 22.3 lbs  
(10.1 kg)  
Specifications are typical; individual units might vary. Specifications are subject to change and improve-  
ment without notice.  
18  
Specifications  
 
32-2003.fm Page 19 Tuesday, March 28, 2000 10:45 AM  
ˆ Notes  
19  
Notes  
 
32-2003.fm Page 20 Tuesday, March 28, 2000 10:45 AM  
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 company-owned  
stores and authorized RadioShack franchisees and dealers. EXCEPT AS PROVIDED HEREIN, Ra-  
dioShack MAKES NO EXPRESS WARRANTIES AND ANY IMPLIED WARRANTIES, INCLUDING  
THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE LIMITED  
IN DURATION TO THE DURATION OF THE WRITTEN LIMITED WARRANTIES CONTAINED  
HEREIN. EXCEPT AS PROVIDED HEREIN, RadioShack SHALL HAVE NO LIABILITY OR RE-  
SPONSIBILITY TO CUSTOMER OR ANY OTHER PERSON OR ENTITY WITH RESPECT TO ANY  
LIABILITY, LOSS OR DAMAGE CAUSED DIRECTLY OR INDIRECTLY BY USE OR PERFOR-  
MANCE OF THE PRODUCT OR ARISING OUT OF ANY BREACH OF THIS WARRANTY, IN-  
CLUDING, BUT NOT LIMITED TO, ANY DAMAGES RESULTING FROM INCONVENIENCE, LOSS  
OF TIME, DATA, PROPERTY, REVENUE, OR PROFIT OR ANY INDIRECT, SPECIAL, INCIDEN-  
TAL, OR CONSEQUENTIAL DAMAGES, EVEN IF RadioShack HAS BEEN ADVISED OF THE  
POSSIBILITY OF SUCH DAMAGES.  
Some states do not allow limitations on how long an implied warranty lasts or the exclusion or limita-  
tion of incidental or consequential damages, so the above limitations or exclusions may not apply to  
you.  
In the event of a product defect 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) correct the defect by product repair without charge for parts and  
labor; (b) replace the product with one of the same or similar design; or (c) refund the purchase  
price. All replaced parts and products, and products on which a refund is made, become the prop-  
erty of RadioShack. New or reconditioned parts and products may be used in the performance of  
warranty service. Repaired or replaced parts and products are warranted for the remainder of the  
original warranty period. You will be charged for repair or replacement of the product made after the  
expiration of the warranty period.  
This warranty does not cover: (a) damage or failure caused by or attributable to acts of God, abuse,  
accident, misuse, improper or abnormal usage, failure to follow instructions, improper installation or  
maintenance, alteration, lightning or other incidence of excess voltage or current; (b) any repairs  
other than those provided by a RadioShack Authorized Service Facility; (c) consumables such as  
fuses or batteries; (d) cosmetic damage; (e) transportation, shipping or insurance costs; or (f) costs  
of product removal, installation, set-up service adjustment or reinstallation.  
This warranty gives you specific legal rights, and you may also have other rights which vary from  
state to state.  
RadioShack Customer Relations, 200 Taylor Street, 6th Floor, Fort Worth, TX 76102  
We Service What We Sell  
12/99  
RadioShack  
A Division of Tandy Corporation  
Fort Worth, Texas 76102  
32-2003  
03A00  
Printed in China  
 

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