Crown_Com-Tech_10_Series_Reference_Manual电路图.pdf

101969-6 3/01 Models: Com-Tech 210, 410, 810 how- ever, an unlimited number of R.S.V.P. modules can be slaved together to accommodate any system size. The power on/off function is controlled from an IQ-Sys- tem AUX or Control Port or from a simple remote con- tact-closure switch. When under IQ System control, all remote manual-control switches are automatically dis- abled. This provides priority access to the IQ user and prevents accidental turnoff. For manual switch configu- ration, two normally-open momentary switches are re- quired: one switch provides the signal to turn the unit on, while the second switch provides the signal to turn the unit off (see Figure 3.13). 3.3.4 Output Connection WARNING: Output terminals marked with the sym- bol are dangerous when live. External wiring connected to these terminals requires installation by an instructed person, or should make use of prebuilt wiring and con- nectors. Fig. 3.13 Connecting the RSVP Module Page 22 Com-Tech Power Amplifiers Reference Manual Consider the power handling capacity of your load be- fore connecting it to the amplifier. Crown is not liable for damage incurred at any time due to overpowering. Fus- ing loudspeaker lines is highly recommended (see Sec- tion 3.3.5). Also, please pay close attention to Section 4.1, Precautions. You should always install loudspeaker cables of suffi- cient gauge (wire thickness) for the length used. The resistance introduced by inadequate output cables will reduce the amplifiers power to and motion control of the loudspeakers. The latter problem occurs because the damping factor decreases as the cable resistance increases. This is very important because the amplifiers excellent damping factor can be easily negated by us- ing insufficient cable. Use the nomograph in Figure 3.14 and the following procedure to find the recommended wire gauge (AWG or American Wire Gauge) for your system. 1. Note the load resistance of the loudspeakers con- nected to each channel of the amplifier. If you are using 70-volt output, be sure to determine the load resis- tance of the step-down transformers (Crowns constant voltage computer can help with this, see Section 8.3). Mark this value on the Load Resistance line of the no- mograph. 2. Select an acceptable damping factor and mark it on the Damping Factor line. Your amplifier can provide an excellent damping factor of 1,000 from 10 to 400 Hz in Stereo mode with an 8-ohm load. In contrast, typical damping factors are 50 or lower. Higher damping fac- tors yield lower distortion and greater motion control over the loudspeakers. A common damping factor for commercial applications is between 50 and 100. Higher damping factors may be desirable for live sound, but long cable lengths often limit the highest damping factor that can be achieved practically. (Un- der these circumstances, Crowns IQ System is often used so amplifiers can be easily monitored and con- trolled when they are located very near the loudspeak- ers.) In recording studios and home hi-fi, a damping factor of 500 or more is desirable. 3. Draw a line through the two points with a pencil, and continue until it intersects the Source Resistance line. 4. On the 2-Cond. Cable line, mark the length of the cable run. 5. Draw a pencil line from the mark on the Source Resis- tance line through the mark on the 2-Cond. Cable line, and on to intersect the Annealed Copper Wire line. 6. The required wire gauge for the selected wire length and damping factor is the value on the Annealed Cop- per Wire line. Note: Wire size increases as the AWG gets smaller. 40 30 20 15 10 9 8 7 6 5 4 3 2 1 2 5 10 20 50 100 .04 .06 .1 .2 .4 .6 1 2 4 6 10 20 40 5 10 20 50 1 2 100 200 500 1000 2000 5000 8000 5000 1000 500 100 50 10 5 1 .5 .1 .05 .01 #28 #26 #24 #22 #20 #18 #16 #14 #12 #10 #8 #6 #4 #2 #0 #00 #0000 R LOAD RESISTANCE (ohms) L R R DAMPING FACTOR L S R SOURCE RESISTANCE (ohms) S 2-COND. CABLE (feet) ANNEALED COPPER WIRE (AWG) (ohms/1000 ft.) Example Shown: R = 8 ohms; R = 0.016 ohms or D.F. = 500; Cable Length = 10 ft.; answer: #8 wire LS 1 0.5 200 500 1,000 2,000 20,000 5,000 10,000 .01 .001 .02 .004 .006 .002 .0004 .0006 .0002 0.6 0.7 0.8 1.5 0.9 Fig. 3.14 Wire Size Nomograph Page 23 Com-Tech Power Amplifiers Reference Manual 7. If the size of the cable exceeds what you want to use, (1) find a way to use shorter cables, like using the IQ System, (2) settle for a lower damping factor, or (3) use more than one cable for each line. Options 1 and 2 will require the substitution of new values for cable length or damping factor in the nomograph. For option 3, esti- mate the effective wire gauge by subtracting 3 from the apparent wire gauge every time the number of con- ductors of equal gauge is doubled. So, if #10 wire is too large, two #13 wires can be substituted, or four #16 wires can be used for the same effect. SOLVING OUTPUT PROBLEMS High-frequency oscillations can cause your amplifier to prematurely activate its protection circuitry. The ef- fects of this problem are similar to the RF problems de- scribed in Section 3.3.2. To prevent high-frequency oscillations: 1. Bundle together each pair of loudspeaker conduc- tors when using long cable runs or when different amplifiers use a common cable tray or jacket. (Do NOT bundle wires from different amplifiers.) This reduces the chance of conductors acting like an- tennas to transmit or receive the high frequencies that can cause oscillation. 2. Avoid using shielded loudspeaker cable. 3. Never tie together input and output grounds. 4. Never tie together the output of different amplifiers. 5. Keep output cables separated from input cables. 6. Install a low-pass filter in series with each input (see Section 3.3.2). 7. Install the input wiring according to the instructions in Section 3.3.2. Another problem to avoid is the presence of large infra- sonic currents when primarily inductive loads are used. Examples of inductive loads are 70-volt trans- formers and electrostatic loudspeakers. Inductive loads can appear as a short circuit at low fre- quencies. This can cause the amplifier to produce large low-frequency currents and activate its protection cir- cuitry. Always take the precaution of installing a high- Fig. 3.15 Inductive Load (Transformer) Network 4 ohm, 20 watt Resistor 590 to 708 f Capacitor 120 VAC, N.P. + Inductive Load + From Amplifier Output pass filter in series with the amplifiers input when induc- tive loads are used. A three-pole, 18-dB-per-octave fil- ter with a 3 dB frequency of 50 Hz is recommended (some applications may benefit from an even higher 3 dB frequency). Such a filter is described with infrasonic frequency problems in Section 3.3.2. Another way to protect inductive loads from large low- frequency currents and prevent the amplifier from pre- maturely activating its protective systems is to parallel a 590 to 708 F nonpolarized motor start capacitor and a 4-ohm, 20-watt resistor in series with the amplifier out- put and the positive (+) transformer lead. This circuit is shown in Figure 3.15. It uses components that are avail- able from most electrical supply stores. 3.3.5 Additional Load Protection Com-Tech amplifiers can generate enormous power output. Using 8/4-ohm output, if your loudspeakers do not have built-in protection from excessive power, its a good idea to protect them. Loudspeakers are subject to thermal damage from sustained overpowering and mechanical damage from large transient voltages. In both cases, special fuses may be used to protect your loudspeakers, or you may opt for the convenience of a PIP module that provides loudspeaker protection. Two different types of fuses are required for thermal pro- tection and voltage protection. Slow-blow fuses are usu- ally selected to protect loudspeakers from thermal damage because they are similar to loudspeakers in the way they respond to thermal conditions over time. In contrast, high-speed instrument fuses like the Littelfuse 361100 series are used to protect loudspeak- ers from large transient voltages. The nomograph in Fig- ure 3.16 can be used to select the properly rated fuse for either type of loudspeaker protection. There are mainly two different approaches used when installing fuses for loudspeaker protection. A common practice is to put a single fuse in series with the output of each channel. This makes installation easy because there is only one fuse per channel to install, but it can also lead to problems. The biggest disadvantage be- comes apparent if the fuse blows because power to all connected loads will be removed. A better approach is to fuse each driver independently. This allows you to apply the most appropriate protec- tion for the type of driver being used. In general, low- frequency drivers (woofers) are most susceptible to thermal damage and high-frequency drivers (tweeters) are usually damaged by large transient voltages. This means that your loudspeakers will tend to have better protection when the woofers are protected by slow-blow Page 24 Com-Tech Power Amplifiers Reference Manual fuses and high-frequency drivers are protected by high- speed instrument fuses. Depending on the application, you may want to use a PIP module to protect your loudspeakers. When prop- erly configured, all PIP modules with signal-driven com- pression can provide loudspeaker protection. Some of the PIP modules with signal-driven compression in- clude the P.I.P.-AMCb, P.I.P.-EDCb and P.I.P.-PA. While the P.I.P.-EDCb is most commonly used for general loudspeaker protection, the P.I.P.-AMCb is very popular in systems that require a high-quality crossover, and the P.I.P.-PA is the processor of choice for applications that require a microphone and line level input for each chan- nel. For more information on PIP modules, see Section 8. 3.4 AC Power Requirements All 120 VAC, 60 Hz North American units have a NEMA 5-15 AC plug with an integral voltage presence lamp. These units include a 16 gauge cord with Com-Tech 210s and 410s, and a 14 gauge cord with Com-Tech 810s and 1610s. Other Com-Tech amplifiers are fur- nished with an appropriate AC cord and plug. All Com- Tech “10” Series amplifiers utilize a convenient, 3-foot- long power cord. To meet full regulatory system com- pliance, these cords must be plugged into a local, cabinet mounted, commercial grade electrical out- let box. “Extension” cords are not recommended or adequate. Use an isolated wall outlet whenever possible with the correct voltage and adequate current. Voltages greater than 10% above the specified AC mains voltage for the amplifier may damage the 15 volt regulator, filter ca- pacitors and output transistors. See Section 7 for power requirements under various conditions. All specifications in this manual were measured using 120 VAC, 60 Hz power unless otherwise noted. Specifi- cations are derived using a mains voltage that is accu- rate to within 0.5% with THD less than 1.0% under all testing conditions. Performance variations can occur at other AC voltages and line frequencies. In addition, line regulation problems will directly affect the output power available from the amplifier. “Soft-Start” inrush current limiting, protects the house circuit breaker when several amps are turned on simul- taneously. Fig. 3.16 Loudspeaker Fuse Nomograph 1.0 1.2 1.4 1.6 2.5 3 4 5 6 7 8 9 10 12 14 16 20 25 30 20 15 10 8 6 5 4 3 2 1.5 1 .8 .6 .5 .4 .3 .2 .15 .1 .08 3000 2000 1500 1000 800 600 400 300 200 150 100 80 60 40 30 20 15 10 8 6 4 3 2 1.5 1 SPEAKER Z (ohms) FUSE (amps) SPEAKER RATING PEAK MUSIC POWER (watts) (Typically 4 times the continuous average power) Example: Z = 8 ohms. Peak Power = 75 W Answer: Fuse = 1.5 A 2 40 Page 25 Com-Tech Power Amplifiers Reference Manual 4 Operation 4.1 Precautions Com-Tech amplifiers are protected from internal and ex- ternal faults, but you should still take the following pre- cautions for optimum performance and safety: 1. Improper wiring for the Dual, Bridge-Mono and Parallel- Mono modes, as well as the 8/4-ohm and 70-volt output modes can result in serious operating difficulties. Refer Section 3.3.1 for details. 2. WARNING: Never operate the amplifier in Bridge- Mono or Parallel-Mono mode unless both outputs are configured the same (8/4-ohm or 70-volt). 3. When driving an inductive load (like a 70-volt step- down transformer) use a high-pass filter or protective network to prevent premature activation of the amplifiers protection circuitry (see Section 3.3.3). 4. WARNING: Do not change the position of the dual/ mono switch or the output mode switches unless the amplifier is first turned off. 5. CAUTION: In Parallel-Mono mode, a jumper must be installed between the Channel 1 and 2 positive (+) output terminals. Be sure to remove this jumper for Dual or Bridge-Mono modes, otherwise high distor- tion and excessive heating will occur. Check the dual/mono switch on the back panel for proper position. 6. Turn off the amplifier and unplug it from the AC power before removing a PIP module or before re- moving the dust filter. 7. Use care when making connections, selecting signal sources and controlling the output level. The load you save may be your own! 8. Do not connect input and output ground leads together. Ground loops and oscillations may result. 9. Operate the amplifier from AC mains of not more than 10% above or below the selected line voltage and only the specified line frequency. 10. Never connect the output to a power supply output, battery or power main. Electrical shock may result. 11. Tampering with the circuitry by unqualified personnel, or making unauthorized circuit changes may be hazard- ous and invalidates all agency listings. Remember: Crown is not liable for damage that results from overdriving other system components. 4.2 Indicators The front panel of a Com-Tech amplifier has several helpful indicators. The amber Enable indicator shows that the amplifier has been turned on (or enabled). It will dim when the unit goes into energy-saving mode. When the Enable indicator is lit, the low-voltage power supply is working. It does not indicate the status of the high- voltage power supplies. For example, the Enable indi- cator will remain lit in the unlikely event that one of the amplifiers protection systems (described in Sec- tion 4.3) puts the channel in “standby” mode. The En- able indicator will stay on for all conditions shown in Figure 4.2 except for the first example, “There is no power to the amplifier.” The green ODEP indicators confirm the normal opera- tion of Crowns patented Output Device Emulation Pro- tection circuitry. During normal operation, they glow brightly to confirm the presence of reserve thermal-dy- namic energy. They dim proportionally as the energy reserve decreases. In the rare event that there is no re- serve, they will turn off and ODEP will proportionally limit the drive level of the output stages so the amplifier can continue safe operation even when conditions are se- vere. (See S