Please read before using this equipment. 32-2001.
32-2001.fm Page 2 Friday, February 4, 2000 7:53 AM ˆ Contents Features ................................................................................................................... 3 Preparation .............................................................................................................. 4 Presetting the Controls ....................................................................................... 4 Choosing a Location ...............................................................
2-2001.fm Page 3 Friday, February 4, 2000 7:53 AM ˆ Features Your RadioShack 20-Watt PA Amplifier gives you 20 watts of solid power for your PA system. Its wide frequency response easily handles amplification of voice and music. It operates on either 120 volts AC or 12 volts DC power so you can use it anywhere you want to deliver special announcements or play music with great sound. Your amplifier is ETL listed to UL standards and meets all applicable FCC standards.
32-2001.fm Page 4 Friday, February 4, 2000 7:53 AM ˆ Preparation PRESETTING THE CONTROLS Warning: A sudden high output from the amplifier could damage your hearing or the speakers connected to the amplifier’s output. To avoid accidentally overdriving a channel or prematurely amplifying an audio input, set all the amplifier’s frontpanel controls to their lowest settings. To avoid sudden audio from the input sources, be sure all audio devices are turned off before you connect them to the amplifier.
32-2001.fm Page 5 Friday, February 4, 2000 7:53 AM PHONO/AUX/CD Switch — select the input source. Even if you connected auxiliary equipment to both the PHONO and AUX/CD input jacks, you can use only one source at a time. Speaker Push Terminals — press the appropriate tab to open a terminal. Insert the end of a speaker wire into the opening, then release the tab to close the terminal and secure the wire (see “Connecting Speakers” on Page 7).
32-2001.fm Page 6 Friday, February 4, 2000 7:53 AM 3. Touch the positive end of a 1.5-volt flashlight battery to the speaker terminal that does not have the wire attached to it. 4. Touch the negative end of the battery with the lose end of the wire attached to the other speaker terminal. Note the direction of the cone movement — inward or outward. 5. If the speaker cone moves outward, the speaker terminal where you touched the positive end of the battery is positive.
32-2001.fm Page 7 Friday, February 4, 2000 7:53 AM • If you connect more than two speakers using only series or only parallel connections, the total impedance might exceed the amplifier’s maximum impedance (16 ohms) or fall below its minimum impedance (4 ohms). You can connect one or more 4-, 8-, or 16-ohm speakers, with or without transformers, between the amplifier’s output and the speakers’ input.
32-2001.fm Page 8 Friday, February 4, 2000 7:53 AM you can make the correct connection. The total impedance of all the speakers must match one of the amplifier’s output terminals (4Ω, 8Ω, or 16Ω). Speakers in Series 1. To determine the total impedance of speakers connected in series, add the impedance of all the speakers.
32-2001.fm Page 9 Friday, February 4, 2000 7:53 AM impedance of one pair of speakers) by 2 (the number of speaker pairs) for a total speaker impedance of 8 ohms. 5. Connect the negative (–) terminals of all pairs of speakers to the amplifier’s COM terminal. Four 8Ω Speakers 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. If you connect these speakers in parallel, the total impedance is 2 ohms (8 ÷ 4 = 2).
32-2001.fm Page 10 Friday, February 4, 2000 7:53 AM Cautions: • Before you connect the speakers, be sure the total wattage of the primary taps you intend to use does not exceed the amplifier’s maximum 20-watt output power rating. Taps • Avoid multiple connections to the amplifier’s 70V and COM terminals. You need a separate transformer for each speaker. Line transformers have several connectors called taps. The primary taps (on one side of the transformer) are the inputs and are rated in watts.
32-2001.fm Page 11 Friday, February 4, 2000 7:53 AM 3. Connect a wire from the speaker’s positive (+) terminal to the transformer’s secondary tap that matches the speaker’s total impedance (4, 8, or 16 ohms). 4. Connect a wire from the speaker’s negative (–) terminal to the COM tap on the transformer’s secondary side. ˆ Controls and Operation MICROPHONE 1 and 2 Inputs — connect any standard dynamic microphones. POWER Switch and Indicator — press the bottom half of the switch to turn on the amplifier.
32-2001.fm Page 12 Friday, February 4, 2000 7:53 AM ˆ Troubleshooting If you should run into difficulties, check the wiring of the system. Are there any short circuits in the speaker wiring? Have you provided adequate ventilation? Did you calculate speaker impedance correctly? Be sure microphones and connecting cables are not defective. Be sure you are using large enough speaker wire. You should always use 16-gauge (or larger) wire. The longer the run of speaker wire, the heavier the gauge should be.
32-2001.fm Page 13 Friday, February 4, 2000 7:53 AM ˆ Care and Maintenance To enjoy your amplifier for a long time: • 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 gently and carefully. Don’t drop it. • Keep the amplifier away from dust and dirt. • Wipe the amplifier with a damp cloth occasionally to keep it looking new.
32-2001.fm Page 14 Friday, February 4, 2000 7:53 AM ˆ Specifications Output Power at 1 kHz, 10% THD ............................................................................... 20 Watts THD at 1W, 1 kHz Low-Pass Filter MIC1 .............................................................................................................................. MIC2 .............................................................................................................................. AUX CD ..................
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32-2001.fm Page 16 Friday, February 4, 2000 7:53 AM Limited One-Year Warranty This product is warranted by RadioShack against manufacturing defects in material and workmanship under normal use for one (1) year from the date of purchase from RadioShack company-owned stores and authorized RadioShack franchisees and dealers.
