32-2054
40-Watt
PA Amplifier
Thank you for purchasing your 40-Watt PA Amplifier from
RadioShack. It gives you the versatility and power you need in
a professional sound system. Your amplifier’s wide frequency
response easily handles amplification of voice and music. Use it
in meeting halls and auditoriums, at sports events, in schools,
and in the office for paging systems—anywhere you need to
deliver special announcements with excellent sound.
What’s Included
PA Amplifier
Fuse (Installed)
User’s Guide
AC Power Cord
DC Power Cord
Please read this user’s guide before installing, setting up, and
using your new amplifier.
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Contents
Quick Start
Contents
Quick Start
Quick Start .......................................................................................... 3
Follow these steps to quickly set up your PA Amplifier. For detailed operation
instructions, see Pages 6-14.
A Look at Your Amplifier..................................................................... 6
Front View........................................................................................................6
Rear View.........................................................................................................7
Step 1 Connect optional components (microphones,
tuners, turntables, CD players, tape decks, or extra
AMPLIÞERꢀꢁTOꢁEXPANDꢁYOURꢁSYSTEMꢂ
Preparation.......................................................................................... 8
Placing the Amplifier ......................................................................................8
Placing Speakers.............................................................................................8
Presetting the Controls...................................................................................8
Presetting the Audio Input Sources.........................................................8
Presetting the Amplifier............................................................................8
Tips for Speaker Connection .........................................................................9
Total Speaker Impedance.........................................................................9
Proper Phasing ..........................................................................................9
About Speaker Terminals .........................................................................9
Determining the Speaker Wire Length ...................................................9
AUX/CD
Connect high-level sound
PHONO AUX/CD
sources, such as CD player,
tape deck, or tuner.
MIX BUS
Use a shielded cable with
phono plugs to connect to
another MP-40 amplifier.
Connections ...................................................................................... 10
Connecting Speaker Wires to the Amplifier...............................................10
Connecting One Speaker.............................................................................10
Connecting Two Speakers in Series ............................................................11
Connecting Two Speakers in Parallel ..........................................................11
Connecting Four Speakers in Series and Parallel Combination...............12
Connecting Speakers with Transformers ....................................................13
PHONO
Connect low-level sound sources, such as a turntable.
Note: Set the PHONO AUX/CD switch to PHONO.
Troubleshooting................................................................................ 15
Specifications .................................................................................... 16
MIC 1, MIC 2
Connect up to two
microphones.
Care and Maintenance...................................................................... 16
Replacing the DC Power Cord’s Fuse .........................................................16
Caution: Before connection, turn off your amplifier and components and set
their volume controls to minimum. To prevent hum and other noise, use low-
capacitance shielded cables.
Safety ................................................................................................ 17
Do Stuff............................................................................................. 19
Limited Warranty............................................................................... 20
3TEPꢁꢃꢁ #ONNECTꢁSPEAKERSꢁTOꢁYOURꢁAMPLIÞER
Connect your speakers together in series, in parallel, or in series and parallel
combination. Then connect the speaker’s negative terminals to amplifier’s
COM terminal, and their positive terminals to the amplifier’s 4Ÿ, 8Ÿ, 16Ÿ, or
70V terminal.
2
3
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Quick Start
Quick Start
4) Adjust the following controls to the desired volume and balance:
MIC 1, MIC 2, PHONO/AUX, 100Hz, 1kHz, and 8 kHz.
5) When you get the desired balance, adjust MASTER VOLUME to the
desired level.
Retaining Catch
Power Indicator
LEVEL Indicator (in dB)
MASTER VOLUME
Press down the retaining catch of the
correct terminal and insert the wire end
into the terminal’s hole. Then, release
the retaining catch to secure the wire.
To speaker’s positive terminal
To speaker’s negative terminal
3TEPꢁꢄꢁ 0OWERꢁYOURꢁAMPLIÞER
To use AC power, use the AC power cord to connect your amplifier’s AC IN
jack to a standard wall outlet.
MIC 1 and MIC 2
Volume Controls
TONE CONTROL
(100Hz, 1kHz, 8kHz)
To use DC power, use the DC power cord to connect your amplifier’s DC 12V IN
jack to a vehicle’s 12V accessory socket.
PHONO/AUX Volume Control
POWER
Step 5 Monitor the sound source
Insert the ¼” (6.35 mm) plug of either mono or stereo headphones (not
supplied) to the PHONES jack. Headphones help easily check and adjust the
balance of the sound sources.
DC 12V IN
AC IN
Cautions:
•
Your vehicle must have a negative ground electrical system. If you are not
sure of this, check with your vehicle dealer.
•
Disconnect the AC power cord before you connect the DC power cord.
Likewise, disconnect the DC power cord before you connect the AC
power cord.
PHONES Jack
3TEPꢁꢅꢁ 5SEꢁYOURꢁAMPLIÞER
1) Turn on the POWER switch. The power indicator lights.
2) Start the input sound source.
3) Set MASTER VOLUME to about the middle position. The LEVEL Indicator
ßASHESꢀONꢀFROMꢀLEFTꢀTOꢀRIGHTꢀINDICATINGꢀTHEꢀSOUNDꢀLEVELꢁ
4
5
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A Look at Your Amplifier
A Look at Your Amplifier
Rear View
A Look at Your Amplifier
L/R PHONO Jacks
Connect a turntable.
GND
Front View
Connect a ground wire
(black or green) to avoid
low-frequency hum.
POWER
Turn the amplifier
on or off.
PHONO/AUX Volume Control
Adjust the volume of the turntable
or auxiliary sound source.
Terminals (COM, 4Ÿ, 8Ÿ,
AC OUTLET (UNSWITCHED)
Supply power (maximum load of
100W) to a musical instrument or
another amplifier.
16Ÿ, 70V)
Connect speaker wires to
the selected terminals.
LEVEL Indicator (in dB)
Monitors and controls
the output power level.
Power Indicator
Lights when the amplifier
is turned on.
PHONO AUX/CD Switch
Select turntable or other
audio input source.
DC 12V IN Jack
Power the
amplifier from a
5A, 12V vehicle
battery source.
PHONES Jack
Connect
headphones
to hear mixed
audio in privacy.
MIC 1 and MIC 2
MASTER VOLUME
Adjust the overall
sound level.
Volume Controls
Adjust the levels of
the microphones
separately.
AUX/CD Input Jacks
Connect a variety of audio
input sources for music and
special effects.
AC IN
Connect to a
standard AC outlet
using the supplied
MIC 1 and MIC 2
TONE CONTROL (100Hz, 1kHz, 8kHz)
Enhance the sound or tailor the high,
medium, and low frequencies for each
audio source input to the acoustics of a
particular performance environment.
Input Jacks
MIX BUS Jack
Connect an extra
amplifier for
multiple audio
sources.
Connect up to two
dynamic microphones.
AC power cord.
6
7
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Preparation
Preparation
Tips for Speaker Connection
Preparation
Placing the Amplifier
Put your amplifier to a place 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 overheating).
You can connect one or more 4Ÿ, 8Ÿ, or 16Ÿ speakers (not supplied) to
the amplifier, with or without transformers. To ensure equal volume from
each speaker, all the speakers connected (in series or parallel) without line
transformers should have the same impedance rating.
Total Speaker Impedance
Before you connect speakers to the amplifier, determine the speaker
connection mode: in series, in parallel, or in series and parallel combination,
then determine the total speaker impedance.
Placing 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 locations that result in best sound. For best results,
point the speakers toward the listeners, especially if you place the speakers
far apart so their coverage areas overlap. This prevents dead spots (areas not
covered by the speakers’ sound). Position the speakers slightly above the level
of the listeners’ heads, and be sure you have determined the correct speaker
impedance (see “Total Speaker Impedance” on Page 9).
For connections in series, the total impedance is the sum of the impedances
of all the speakers connected. For example, if you connect three 4Ÿ speakers
in series, the total speaker impedance is 12Ÿ.
For connections in parallel, the total impedance is the quotient of the
impedance of one speaker divided by the number of speakers. For example, if
you connect two 8Ÿ speakers in parallel, the total speaker impedance is 4Ÿ.
Important: If you connect more than two speakers in series only or in parallel
only, be sure the total impedance does not exceed the amplifier’s maximum
impedance (16Ÿ) or fall below the minimum impedance (4Ÿ). A total speaker
impedance higher than 16Ÿ or lower than 4Ÿ can damage your amplifier.
Note: You can achieve a proper total speaker impedance with a combination
of connections in series and in parallel.
Presetting the Controls
Before you begin making connections or using your amplifier, preset the
audio input and amplifier controls to avoid overdriving a channel or producing
extremely loud, unpleasant sound.
Presetting the Audio Input Sources
Set the audio input controls to these levels.
Proper Phasing
Audio Device
Turntable
Control
Power
Power
Power
Setting
Off
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 half of their potential
volume, and can have a significantly decreased bass effect. Proper phasing
occurs when speakers are set to allow sound to flow in the same direction.
Tape Deck
CD Player
Off
Off
About Speaker Terminals
Power,
Tone
Off,
Flat
Amplifier Receiver
Most speaker terminals are color-coded or have a symbol that indicates the
terminal’s polarity: red (+) = positive; black (–) = negative. Phasing is correct
when you connect this way: speaker’s negative terminal to amplifier’s COM
terminal (–), speaker’s positive terminal to amplifier’s other terminals.
Presetting the Amplifier
After you turn on the amplifier or change the program source, set the controls
to a comfortable listening level.
Determining the Speaker Wire Length
Warning: To prevent possible hearing damage, set the amplifier’s controls to
Use the shortest length of wire possible to connect the speakers. After placing
the speakers in the desired locations, determine the wire length and choose
the appropriate gauge size.
the levels below.
Control
Power
Setting
Off
MIN
•
•
If wire length is 25 feet (7.6 meters) or less, wire gauge is 18.
If wire length is over 25 feet, wire gauge is 16.
MIC 1, MIC 2, PHONO/AUX
100 Hz, 1 kHz, 8 kHz
MASTER VOLUME
0 dB (mid-position)
MIN
If you connect speakers without transformers, the speaker wire should be no
longer than 50 feet (15.24 meters).
8
9
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Connections
Connections
Connecting Two Speakers in Series
Connections
Connecting Speaker Wires to the Amplifier
1. Use a wire stripper (not supplied) to remove about half inch of the
insulation from the end of the speaker wire.
•
Connect the two speakers together, Speaker A’s positive terminal to
Speaker B’s negative terminal.
•
•
Connect Speaker A’s negative terminal to the amplifier’s COM terminal.
Connect Speaker B’s positive terminal to the amplifier’s 4Ÿ, 8Ÿ, or 16Ÿ
2. Using a wire connector (not supplied), twist the exposed wire to secure all
the wire strands. Remove the wire connector for step 3.
terminal.
3. Press and hold the retaining catch of the correct terminal on the amplifier
and insert the wire into the terminal’s hole. Release the retaining catch to
secure the wire.
Amplifier Terminals
‘
Wire Connector
Retaining Catch
Speaker B
Speaker A
Connecting Two Speakers in Parallel
•
Connect the negative terminals of the two speakers together, and then
Connecting One Speaker
Connect the speaker’s negative (–) terminal to the amplifier’s COM terminal,
and the speaker’s positive (+) terminal to the amplifier’s 4Ÿ, 8Ÿ, or 16Ÿ
terminal.
connect both wires to the amplifier’s COM terminal.
•
Connect the positive terminals of the two speakers together, and then
connect both wires to the amplifier’s 4Ÿ, 8Ÿ, or 16Ÿ terminal.
Speaker A
Amplifier Terminals
Amplifier Terminals
Speaker Terminals
Speaker B
10
11
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Connections
Connections
Connecting Four Speakers in Series and Parallel Combination
Connecting Speakers with Transformers
1. Group the four speakers into two pairs (A and B, C and D). Connect each
pair of speakers in series: A’s positive terminal to B’s negative terminal, C’s
negative terminal to D’s positive terminal.
For best results when using two or more speakers, connect a line transformer
(not included) to each speaker. Transformers allow you to:
•
•
•
Connect speakers with different impedances without causing output
differences between the speakers.
If you use all 8Ÿ speakers, the total impedance of a pair is 16Ÿ.
2. Connect the two pairs together in parallel: A’s negative terminal to D’s
negative terminal, B’s positive terminal to C’s positive terminal.
If you use all 8Ÿ speakers, the total impedance of the four speakers thus
connected is 8Ÿ ((8+8)/2=8).
3. Connect the negative terminals of Speakers A and D to the amplifier’s
COM terminal, and the positive terminals of Speakers B and C to the
amplifier’s 4Ÿ, 8Ÿ, or 16Ÿ terminal.
Add or remove a speaker from the PA system without having to recalculate
the entire system’s impedance.
Reduce signal loss when using a speaker wire over 50 feet (15.24 meters)
long.
Line transformers have primary connection taps on the input side, which are
rated in watts, and secondary connection taps on the output side, which are
rated in ohms. Before you connect speakers, be sure the total wattage of the
primary taps you use does not exceed the amplifier’s maximum output power
rating (40W).
The following illustration shows how to connect three speakers with
transformers.
Amplifier Terminals
•
•
•
•
Connect the amplifier’s 70V terminal to the primary taps (10, 5, 2.5, 1.25, or
0.62 watts) of the transformer.
Connect the amplifier’s COM terminal to the C (common) taps on the Input
Side of the transformer.
Connect the speaker’s positive terminal to the transformer’s 4Ÿ, 8Ÿ, or 16Ÿ
tap (whichever matches the total speaker impedance).
Connect the speaker’s negative terminal to the C tap on the Output Side
of the transformer.
Notes:
Speaker A
Speaker B
Speaker D
Speaker C
•
•
•
Do not connect multiple wires to the amplifier’s 70V and COM terminals.
Wires with the mark are to be connected together.
Usually, a speaker in a system uses the same wattage tap of its transformer.
If you want a particular speaker to have a higher volume level, connect
the wire from the amplifier’s 70V terminal to a higher wattage tap on the
transformer.
A
Illustration on Page 14
12
13
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Connections
Troubleshooting
Troubleshooting
Transformer
Problem
Cause
Solution
Sound sources or speakers
are not properly connected.
Check all connections.
No power
No sound
Feedback
The MASTER VOLUME,
Adjust the volume controls to
MIC 1, MIC 2, PHONO/AUX, desired settings.
100 Hz, 1 kHz, 8 kHz controls
are set to minimum.
Amplifier
Sound sources or speakers
are not properly connected.
Check all connections.
A microphone or cable might Check all microphones and
be faulty or loose.
cables.
The speaker’s wires might be Make sure all speakers
of the wrong impedance.
connected have the same
impedance rating.
A
8Ÿ, 2.5W Speaker
The speaker’s wires might be Make sure the speaker’s
too small.
wires are the correct gauge
according to their lengths.
A
A
The amplifier might have shut Turn off the amplifier and let
down.
A
Transformer
Transformer
it cool down. Make sure the
amplifier is properly ventilated,
and then turn it back on.
Microphones or speakers are Reposition the microphones
too close together. and speakers.
8Ÿ, 5W Speaker
16Ÿ, 1.25W Speaker
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Specifications
Safety
Specifications
Important Safety Instructions
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
Output Power (at THD 10%, 4Ÿ Load 1kHz)..................................................40W
Total Harmonic Distortion (at 5 Watts, 4Ÿ, 1kHz, with Band Pass Filter)
MIC ......................................................................................................... 0.50%
AUX......................................................................................................... 0.10%
PHONO .................................................................................................. 0.30%
4. Follow all instructions.
5. Unplug this product from the wall outlet before cleaning. Do not use liquid
cleaners or aerosol cleaners. Clean only with dry cloth.
6. Only use attachments/accessories specified by the manufacturer.
7. Do not use this product near water.
Input Sensitivity (at 10%, THD, 1kHz)
8. Use only with the cart, stand, tripod, bracket, or table specified by the
manufacturer or sold with the apparatus. When a cart is used, use caution when
moving the cart/apparatus combination to avoid injury from tip-over.
9. Exercise caution when moving any product and cart combination. Quick
stops, excessive force, and uneven surfaces may cause the appliance and cart
combination to overturn.
10. Slots and openings in the cabinet are provided for ventilation and to ensure
reliable operation of the product and to protect it from overheating. Do not block
any ventilation openings. Install in accordance with the manufacturer’s instructions.
11. Use only the type of power source indicated on the label. If you are not sure of the
type of power supply to your home, consult your product dealer or local power
company. For products intended to operate on battery power, or other sources,
refer to the operating instructions.
MIC ........................................................................................................2.5 mV
AUX.......................................................................................................150 mV
PHONO .................................................................................................3.5 mV
Signal to Noise Ratio with A-WTD
MIC ..........................................................................................................60 dB
AUX..........................................................................................................80 dB
PHONO ...................................................................................................70 dB
Hum and Noise at 4Ÿ
At MASTER VOLUME MIN......................................................................1 mV
At MASTER VOLUME MAX ..................................................................50 mV
12. Do not defeat the safety purpose of the polarized or grounding-type plug. A
polarized plug has two blades with one wider than the other. A grounding type
plug has two blades and a third grounding prong. The wide blade or the third
prong are provided for your safety. If the provided plug does not fit into your
outlet, consult an electrician for replacement of the obsolete outlet.
Alternate Warnings: This product is equipped with a three-wire grounding-type
plug, a plug having a third (grounding) pin. This plug will only fit into a grounding-
type power outlet. This is a safety feature. If your are unable to insert the plug into
the outlet, contact your electrician to replace your obsolete outlet. Do not defeat
the safety purpose of the grounding-type plug.
Power Supply ..............................................................120V AC, 60Hz; or 12V DC
Dimensions (W×D×H) .......................... 12.8 × 8.9 × 3.3 in (324 × 226 × 85 mm)
Specifications are subject to change and improvement without notice. Actual product
may vary from the images found in this document.
Care and Maintenance
13. Protect the power cord from being walked on or pinched particularly at plugs,
convenience receptacles, and the point where they exit from the apparatus.
14. Protective Attachment Plug: The product is equipped with an attachment
plug having overload protection. This is a safety feature. See Instruction Manual
for replacement or resetting of protective device. If replacement of the plug is
required, be sure the service technician has used a replacement plug specified by
the manufacturer that has the same overload protection as the original plug.
15. If an outside antenna is connected to the receiver, be sure the antenna system is
grounded so as to provide some protection against voltage surges and built-up
static charges. Article 810 of the National Electrical Code, ANSI/NFPA 70, provides
information with regard to proper grounding of the mast and supporting structure,
grounding of the mast and supporting structure, grounding of the lead-in wire
to an antenna-discharge unit, size of grounding conductors, location of antenna-
discharge unit, connection to grounding electrodes, and requirements for the
grounding electrode.
•
•
•
•
Keep the amplifier dry; if it gets wet, wipe it dry immediately.
Use and store the amplifier only in normal temperature environments.
Handle the amplifier carefully; do not drop it.
Keep the amplifier away from dust and dirt, and wipe it with a damp cloth
occasionally to keep it looking new.
•
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 local RadioShack store for
assistance.
Replacing the DC Power Cord’s Fuse
If the amplifier does not operate from a 12V battery source, check the fuse in
the DC power cord plug. If the fuse is blown, remove the cap of the plug and
replace the fuse with one of the proper type and rating (6A, 250V).
16. Unplug this apparatus during lightning storms or when unused for long periods of
time.
16
17
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Safety
Do Stuff
17. An outside antenna system should not be located in the vicinity of overhead power
lines or other electric light or power circuits, or where it can fall into such power
lines or circuits. When installing an outside antenna system, extreme care should
be taken to keep from touching such power lines or circuits as contact with them
might be fatal.
Do More with your Amplifier
18. Do not overload wall outlets, extension cords, or integral convenience receptacles
as this can result in a risk of fire or electric shock.
19. Never push objects of any kind into this product through openings as they may
touch dangerous voltage points or short-out parts that could result in a fire or
electric shock. Never spill liquid of any kind on the product.
20. Do not attempt to service this product yourself as opening or removing covers may
expose you to dangerous voltage or other hazards. Refer all servicing to qualified
service personnel.
21. Unplug this product from the wall outlet and refer servicing to qualified service
personnel under the following conditions:
7.5-Watt Amplified Speaker
• Amplify over loud noises
Ceiling Speaker
• Easy to install
• Useful for large audience occasions
a) When the power-supply cord or plug is damaged.
b) If liquid has been spilled, or objects have fallen into the product.
c) If the product has been exposed to rain or water.
d) If the product does not operate normally by following the operating
instructions. Adjust only those controls that are covered by the operating
instructions as an improper adjustment of other controls may result in damage
and will often require extensive work by a qualified technician to restore the
product to its normal operation.
e) If the product has been dropped or damaged in any way.
f) When the product exhibits a distinct change in performance – this indicates a
need for service.
22. Replacement Parts: When replacement parts are required, be sure the service
technician has used replacement parts specified by the manufacturer or have the
same characteristics as the original part. Unauthorized substitutions may result in
fire, electric shock, or other hazards.
23. Upon completion of any service or repairs to this product, ask the service
technician to perform safety checks to determine that the product is in proper
operating condition.
Line Transformer
• Connect speakers with different
impedances
• Freely add or remove a speaker
from the PA system
• Reduce signal loss
Headphones
• Avoid disturbing others
• Easily check and adjust balance
of sound sources
24. Do not install near any heat sources such as radiators, heat registers, stoves, or
other apparatus (including amplifiers) that produce heat.
WARNING: 4OꢀREDUCEꢀTHEꢀRISKꢀOFꢀÞREꢀORꢀSHOCKꢀHAZARDꢂꢀDOꢀNOTꢀ
expose this product to rain or moisture.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: 4OꢀREDUCEꢀTHEꢀRISKꢀOFꢀELECTRICꢀSHOCKꢂꢀDOꢀNOTꢀREMOVEꢀ
cover or back. No user-serviceable parts inside. Refer servicing
TOꢀQUALIÞEDꢀPERSONNELꢁ
Wire Connector
• Secure wire strands
Speaker Wire
Dynamic Microphone
• Ideal for high noise
background
This symbol is intended to alert you to the presence of un-
insulated dangerous voltage within the product’s enclosure that
MIGHTꢀBEꢀOFꢀSUFÞCIENTꢀMAGNITUDEꢀTOꢀCONSTITUTEꢀAꢀRISKꢀOFꢀELECTRICꢀ
shock. Do not open the product’s case.
• Provide less loss and
lower attenuation
This symbol is intended to inform you that important
operating and maintenance instructions are included in the
literature accompanying this product.
18
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