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PDF Content Summary: Quality. Uncompromised. ROTEL PUBLIC ADDRESS AMPLIFIER WITH AM/FM TUNER CA-40B INSTRUCTION MANUAL WARNING TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE Write your SERIAL NUMBER here. The number is located near the name place on the regr panol. PRECAUTIONS To ensure maximum safety, please carefully follow the instructions below: 1. Check the power source Plug the unit only into a power source whose voltage and frequency ratings match those given in the instruction manual. 2. Power cord The unit is provided with a 3core type 8.c. line cord with a grounding wire. Insert the plug only into a 3 conductor outler (containing ground. ing wira) of 120V/60Hz. Or if a 3-conductor ourlet is not available, use an adaptor, connecting the grounding wire To B grounding screw on a wall, etc. Insert or unplug the a.c. line card only after making certain the unit's power switch is turned off, to prevent shock noise from damaging the speakers 3. Ventilation To offer heat generated by the unit, it is necessary to provide ample ventilation around the unit. Avoid blocking or impeding the ventilation holes on the unit. To prevent unnecessary problems, install the unit on a place free from any vibrations, direct sunlight, humidity ar dust circulation, 4. Do no apen the cabinet The unit has been completely factory adjusted. To avoid clectric shock or harm to the human body or to the unit, never open the cabinet, 5. If the unit gets wet ar foreign matter enters In cese the unit gets wer or any water or foreign matter gets into the cabinet, immediately disconnect the 9.c. fine card, and consult your desier or qualified electrician. 6. Instruction manual Keep the inatruction manual near the unie, and record the serial number (found on the rear panel) on the cover, (4) MIC 1,2 Level Controls These controls regulate the input levels from microphones connected to the regpective MIC terminals. Rorare each knob clockwise to raise the input level, and counterclockwise to reduce it. Turning the knob fully courterclockwise (to position"D") cuts all input from microphone. (5) TEL PAGE Level Control This knab regulates the level of input from a telephone paging unit connected to the TEL PAGE terminals, Rocate the knob clockwise to raise the level, and counterclockwise to reduce it. Turning the knob fully counterclockwise (10 position "O") cute input from a telephone paging unit. (6) AUX/TUNER Level Control This knob regulates the level of Input from the zuner section of the unir, or from any equipment connected to the PROGRAM/AUX input cerminal on the rear panel, such as chimes, cape deck, rhythm bax. synthesizer, etc. Rotate the knob clockwise to raise the fevel of input from the built-in tuner, and counterclockwise zo raise the level of input from the auxiliary unit. At mid position ('0', input from elcher source is cut, Note: This control operetes on either turer or auxiliary unit, not both at once; signals cannot be fixed. (7) MASTER Volume Control This knob controls az one time the combined signals coming from MICs 1, 2, TEL PAGE and AUX/TUNER. Rorate the knob clockwise to raise the overall level of those signals together, and rotate it coun. terclockwise to reduce it. Tuning the knob fully counterclockwise (to "O" position) cuts all inputs. (8) Tuning Dial This knob tunes In the desired AM or FM broadcast station, Use the lower half of the knob far AM band, and the upper half for FM band reception. Rotate the knob to bring the pointer on the knob to the desired position on the frequency scale around the knob. (9) AFC Switch (FM) This switch is used to prevent tuning drift originating in frequency deviation of lacel oscillator. As a general rule, set the switch to OFF when you tune in to a station, and to ON after tuning is complete, (70) AM/FM Selector This switch selects AM or FM reception. (11) Microphone Input Terminals These are screw-type microphone input terminals. The 2 right hand terminals are for MIC T connections, and the 2 left-hand terminals are for MIC 2 connections, Both MIC 1 and MIC 2 connections can be made simultaneously. These terminals have been already adjusted to accept low impedance (250 ohms) balanced ar unbalanced microphone. SWITCHES, CONTROLS AND OPERATION (1) Power Button Depress this button to turn on power. Pressing It a second time will turn off power, (2) Power Indicator Glows when the power is turned on, indicating that the unit 19 in operation, (3) BASS/TREBLE Tane Controls These are slider-type controls that regulace the balance of core of input aignels coming from AUX/TUNER, BASS regulates the low frequency range and TREBLE the high frequency range, Slide the respec tive knobs to the right to increase the response, and to the left to decrease It. 11 !! PUBLICADOREEE AMPLIFIER ? JE model DA-40B MC TEPAGE AUX TUNEA MASTER AM M MC AM ta The strended wire from the microphones should be hooked up to the common GND. terminal, . MICROPHONE INPUT TERMINAL CONNECTION (14) Ferrite-bar Antenna This is a built-in antenna for use in AM broadcast reception. Erect the bar továrds you, and position it where the reception is optimal (15) Antenna Input Terminals Use the terminels labeled 30032 when parallel feeder is used, and the rerminals labeled 759 for coaxial cable. The AM terminal is used to Connect external antenne when sufficient electric field strength cannot be abtained with the built-in ferrice bar antenna, (16) Music On Hold Terminals Signal form the tuner section of the unit is available through the terminal for connection to a telephone paging unit as music source while telephone is on hold. Adjust a level control underneath the unle (on botom plate) by using screw driver for level Berting. (17) Tel Page Terminals Connect a telephone paging unit. (18) Speaker Terminals Connect 4 co 16-ohm speakers to minus (-) and plus (+) terminals. Or, connect speakers with 2S-volt line transformers to 25V and COM, and speakers with 70-volt line transformers to 70V and COM. Important: Ensure plus (+) and TR terminals are stropped with jumper wire when using 25V and 70V terminals. (19) Overload Protector Button If overload occurs due to Mismatched speaker impedance, etc., remove the cause of the overload and push this button to reser power to the l. ΠΠΙΙ. BALANCED TYPE, LOW IMPEDANCE (250m Length of shielded cord: MIC1 200 feet (60 meters) maximum MIC @lepiple MICZ LMIC UNBALANCED TYPE, LOW IMPEDANCE (2500) Length of shielded cord; 50 feet (18 meters) maximum MICZ MICI (12) Mute Terminals Connect wires from push-to-talk microphone or from telephone system, to mute music or signal from Program/Aux input when talking. (13) Program/Aux Input Terminals Connect an auxiliary equipment such as cape player to the RCA type pin plug. Or. connect 3 600-ohim input such as BGM source to the 600-ohm balanced terminals on connection of the rear panel. Nom: The RCA type pin Jack and the 600-ohm balanced Input terminals cannot be used simultaneously. Use either one or the other, and leave the other unconnêtted. ROTEL MODEL OA-GOF FELI". HOR" INTIACP PLY CO. UNON MY JUST TITAE 15 Sect 60 THAI TAPPI L LNG2 Cm LWIC1 CI TO ACUN. HINC AND MAPOU NO" Lynos FILEFT TO INCT WELL CAUTION-DNVENT ECOTRUYER HOWA ENEO OF SPIRALE PER TE LE PENELOGIO TORTE REFR ATTENTION IN M arch mas LLCRIPCJELLE NOW PUNE ENTILE ALUFLETTURATUR SU LENT EN ETA EMERIONADOESJETA ENETEUR QUOUIL CONSIDERATIONS FOR PA SPEAKER LAYOUT SERIES/PARALLEL COMBINATIONS In larger systems it will be necessary to combine series and paretel con nections to obtain the necessary impedance. The rule for calculating the total effective impedance is to divide the entire circuit into individual smali series of parallel sub-circuits and apply the foregoing rules to them, The rallowing is an example using 16 x 8 Ohm speakers. Esch schematic is an impedance equivalent to its predecessar bur has been simplified. 211-4) = Z1 + Z2 + etc. Z(1-4) = 32 Ohms Z(5-8) ES = 32 Ohms SPEAKER CONNECTIONS In connecting speakers toe public address amplifier it is important to present the amplifier with the load impedance it is designed to handle, Failure to do this can cause overheating and component failure. In marty Gases problems can take months to appear in the form of reduced reliability and unnecessary service calls. A load impedance that is too low is especially bad, You should strive to have a load impedance of not less than 70% of the chosen ermolifler output Impedance, For example, do not connect a 4 Ohm speaker to the 8 Ohm ou tout. Driving a load of higher impedance than rated amplifier output is not as serious, but results in a power loss proportional to the mismatch and should be avoided. For example, driving a 16 Ohm load through the 8 Ohm output will result in a 50% loss in power. The high impedance mismatch should be kept to less than 200%, especially if it is anticipated that more than 50% of the rated amplifier power will be re quired. There are two methods of connecting groups of speakers to the amplifler. Firstly, using the low impedance (i.e. 4, 8, 16 Ohm) Outputs. This is prefer able where: - Lal Auns are short (less than 200 ft. (70 m]). (b) Few horns or speakers are to be used (l.e. typically 4-8) le) Same sound levels are required at cach speaker. (d) Low impedance also provides slightly berper fidelity and frequency response. High impedance or constant voltage is the second method and is preferable where! - (c) The runs are long and line losses are to be avoided. (b) Many speakers are to be used, (c) Different sound levels are required at different locations, for example Indaar speakers and outdoor horns. id) Future expansion possiblities require flexibility in wiring layout. The following is a more detailed discussion of these two methods. Z(9-12) H = 32 Ohms 12 Z(13-16) - 32 Ohms 1/Z1 = 1/Z(1-4) + 1/2(5-8) + 1/Z(9-12)+ 1/Z(13-16) 1/2 - 1/32 + 1/32 + 1/32 Z(1-4) = Z1 + Z2 + 2x + Za Z(5-8) = 2(9–12) = 7(13-16) = 32 Ohms = Zx = 8 Ohms - As can be seen, a problem arises If one more speaker must be added at some future date, as all the connections must be changed. This is not much of a problem If only a few speakers are involved, but if the network is extensive, the problem is significant, in addition, failure of one speaker can take out a mumber of associated units. LOW IMPEDANCE CONNECTION The speekers must be connected so as a present a combined impedance equal to the selected amplifier output impedance, i.c. 4, 8, 16 Ohms. The connections should be arranged in a series/perallel combination to achieve this according to the following formulee. The impedance should be between 70% and 200% of the output impedance selected. If the amplifier is to be driven anywhere neer its full rated output the impedance should be well within these tolerancés. HIGH IMPEDANCE OR CONSTANT VOLTAGE (25V & 70V) SYSTEMS The high impedance or constant voltage method of impedance matching uses a high impedance amplifier output which is transformed down to 8 Ohms by an impedance matching transformer et each individual speaker. The big advantages of this approach is compared to low impedance are: - Series - Connected Speakers (1) Reduced line losses and ability to use smaller wire gauges. This is due to the higher voltage and reduced current in the speaker lines. (2) Much simpler Impedance matching procedures and connections. Constant voimage is a misnomer in that the amplifier does not always produce 70V Rather the amplifier Ou Dur impeden irrespective of its reted power, it will produce 70.7 volts ou tout at full power. Thus a 10 Watt amplifier oprimum load would have an impedance of 500 Ohms (V/P - 70.7°/10), a 40 Watt amp would be 126 Ohms and 100 Wat amp, 50 Ons: 2- + N Z1 = Z1 + Z2 + Z:..... + where ZT total combined load impedance and ZN = individual speaker impedance Parallel - Connected Speakers Multiple transformer raps allow the impedance 9t ench speaker to be adjust ed individually to give y total matched load. Because of the high impedance arrangement, the system is easier to impedance match and te also inherently less susceptible to problems caused by mismatching. The transformer taps are marked in Watts instead of Ohms (usually 4, 2, 1, 6). Again, It should be bamed in mind that mese levels of power output are only achieved when the transformer is working at 70.7 volts. The trans formers are connected in paraller. A good match is obtained by ensuring that the oral af all rap settings fits into the rerge of 40-80% of rated amplifier output. 8096 is chosen to allow for transformer insertion loss. "Ic is also good practice not to drive the amplifier to 100% of its capacity. Examples are shown below. For simplicity it is assumed that all rap battings ara the serre at each speaker. 73 --LV ZT 1/21 + 1/Z2 +1/Z3 + ....1/ZN uzit For 40 Watt amplifier the range 40-80% is equivalent to 16-32 Warts. Therefore: 6 speakers x 4 Watt taps each = 24W ........Good match 4 speakers x 1 Wort taps each = 4w, ......Poor match 20 speakers x 1 Watt taps each = 20w ........Good match 20 speakers 1 4 Watt tapeech = 80w ........Very poor match Overioad 30 speakers z 1 Wats cops each = 30w ..... ...Good merch NOTE: None of the above tep settings guarantee the actual sound levels through each speaker. This is as much a function of the master volume control as the tap setting. The setting simply defines the maximum power consumed by an 8 Ohm speaker of presented with 70.7 volt Input In the case of a small number of speakers, it is always preferable to use a higher tap setting and reduced the sound level by turning down the master volume control. In calculating the amplifier rating needed for a typical music/paging system using speakers distributed in an office environment, a good rule of thumb is to allow about TW per speaker and space speakers & 1% X ceiling height. For noisy areas, or where the volume level required is higher, more power 15 required. (1) Connect one side of a flashlight battery to one of the speaker terminals. (2) Momenterily contact the other speaker terminal to the other side of the battery Note direction of cone movement (inward or outward). Merk the speaker cermine that corresponds to the positive side of the battery. (5) Repeat the same procedure for each successive speaker, making sure that the direction of cone movement is the same for gach case. (6) If the speaker cones are all to move in the same direction, connect the marked terminals to each other and the unmarked terminals to gach other, if the cones are to move in opposite directions, as is the case when two speakers are facing each other, connect the marked terminal of each speaker to the unmarked terminal of each speaker. PHASING When using multiple speakers in a sound system Installation, it is advisable to phase the speakers in order to reduce the cancellation effect caused by improper phasing. Speakers out of phase will lose up to one-hall of their normal volume and will operate with poor tonal characteristics. For speakers facing in the same general direction, the speakers are in phase when all speaker cones move in the same direction when an equal signal is applied. With two speakers facing each other, proper phasing is achieved when the cone of one speaker movas inward while the cene of the other speaker moves outwards. If speakers are unmarked, or not the same model, the following procedure will allow fast and simple phasing. POWER LOSS IN LONG LINES For long lines the power loss in the lines (IR) becomes a significant factor. The power supplied by the amplifier is effectively reduced by the line foss. Far a 0.5 db loss in sound pressure the total wire resistance must be limited to 6% of speaker impedance. The following table shows the calculated two wire cable lengths permissible for a number of wire sizes in feet, For a 1 db loss, the lengths may be doubled. For 2 db loss, multiply by 4.4. Low Impedance AWG Size Resistance I(Ohm/1000 fest) 162 | 492 1 48 1852 98 1190 14 2.50 High-impedance Systernis 100w/70.7V 50W/70.7V 25W/70.7V 12%W/25V 672W/25V | 344W/26V (50) (1002) (2002) 600 1,200 2.400 370 740 1,500 230 460 920 150 300 600 93 190 380 16 4.02 30 60 90 18 20 6.39 1 0.1 16.2 19 112 7 3 8 24 1 14 78 48 26 22 TECHNICAL SPECACATIONS AMPLIFIER SECTION Power Output .................. 40 watts RMS (8 ohms) Frequency Response ............ 50Hz-18kHz, +108, -3dB (8 ohms) Hum and Noise MIC 1,2 Input --............... 55dB below rated output AUX input...... .......... 70dB below rated output TEL PAGE Input ....... 65dB below rated output PROGAAM Input........... 70dB below rated output Sensitivity MIC 1, 2 Inpur ......... O.BmV/250 ohms AUX input............... 150mV/38 kohms TEL PAGE Input ............. 100 mV/6B0 ohms PROGRAM Input.....ti 115mV/600 ohms Outputs..................... 4-16 ohms, 25V (16 ohms) Use with output trans., 70V (122,5 ohms) Use with output trans. Inputs -------- 2 MICs low-impedance), 1 AUX (high-Impedancel/ PROGRAM (low-impedancel, 1 TEL PAGE (high-impedance) Controls.. 2 MIC VOLUMES, 1 TEL PAGE VOLUME, 1 AUX/TUNER VOLUME, MASTER VOLUME, BASS and TREBLE Torre Control Action BASS ... ... .. + 6.0dB, -84B (100Hz) TREBLE...................... +6.0dB, -8dB (10kHz) Muting Level -80dB • Specifications and features subject to possible modification without notice. TUNER SECTION (at MUSIC ON HOLD) Frequency Range .............AM: 535-1.605kHz FM: 88-108MHz Sensitivity ...... . . AM: 500V for 20dB quieting FM: 4V for fod quieting Discordon .......... AM: 1.5%, MOD 30% 400Hz FM: 0.8%, MOD 100% 400Hz Hum and Naise ......... AM: 40dB FM: 5508 Output .................. . AM: 950 mV, MOD 30% 400Hz (ar MUSIC ON HOLD) FM: 2.3V, MOD 100% 400Hz MISCELLANEOUS Power Requirement.............. 120V AC/60Hz Power Consumpdon .......... 105 watts Dimensions .......... 370(W) x 94(H) x 2101D)mm 14-19/32'x3-73/32" XB-9/32" Weight ........ ............. 5.6kg/12.1 lbs PUPP.
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