Crown_Macro-Tech_Series_Reference_Manual电路图.pdf

《Crown_Macro-Tech_Series_Reference_Manual电路图.pdf》由会员分享，可在线阅读，更多相关《Crown_Macro-Tech_Series_Reference_Manual电路图.pdf（42页珍藏版）》请在收音机爱好者资料库上搜索。

1、Models: Macro-Tech 600, 1200 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. 3.13 Wire Size Nomograph Macro-Tech 600/1200/2400 Power Amplifiers Page 17Referenc

2、e Manual 1. Note the load resistance of the loudspeakers connected to each channel of the amplifier. Mark this value on the “Load Resistance” line of the nomograph. 2. Select an acceptable damping factor and mark it on the “Damping Factor” line. Your amplifier can provide an excel- lent damping fact

3、or of 1,000 from 10 to 400 Hz in Stereo mode with an 8-ohm load. In contrast, typical damping fac- tors are 50 or lower. Higher damping factors yield lower dis- tortion and greater motion control over the loudspeakers. A common damping factor for commercial applications is be- tween 50 and 100. High

4、er damping factors may be desirable for live sound, but long cable lengths often limit the highest damping factor that can be achieved practically. (Under these circumstances, Crowns IQ System is often used so amplifiers can be monitored and controlled when they are located very near the loudspeaker

5、s.) In recording studios and home hi-fi, a damping factor of 500 or more is very desir- able. 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 fr

6、om 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 Copper Wire” line. Note: Wire size increases as th

7、e AWG gets smaller. 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 substitu- tion of new values for cable l

8、ength or damping factor in the nomograph. For option 3, estimate the effective wire gauge by subtracting 3 from the apparent wire gauge every time the number of conductors 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

9、 same effect. SOLVING OUTPUT PROBLEMS Sometimes high-frequency oscillations occur which can cause your amplifier to prematurely activate its pro- tection circuitry and result in inefficient operation. The effects of this problem are similar to the effects of the RF problem described in Section 3.3.4

10、. To prevent high- frequency oscillations: 1. Lace together the loudspeaker conductors for each channel; do not lace together the conduc- tors from different channels. This minimizes the chance that cables will act like antennas and transmit or receive high frequencies that can cause oscillation. 2.

11、 Avoid using shielded loudspeaker cable. 3. Avoid long cable runs where the loudspeaker cables from different amplifiers share a common cable tray or cable jacket. 4. Never connect the amplifiers input and output grounds together. 5. Never tie the outputs of multiple amplifiers to- gether. 6. Keep l

12、oudspeaker cables well separated from input cables. 7. Install a low-pass filter on each input line (similar to the RF filters described in Section 3.3.4). 8. Install input wiring according to the instructions in Section 3.3.4. Another problem to avoid is the presence of large sub- sonic currents wh

13、en 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- cuit

14、ry. Always take the precaution of installing a high- pass filter in series with the amplifiers input when inductive loads are used. A 3-pole, 18-dB-per-octave filter with a 3 dB frequency of 50 Hz is recommended (depending on the application, an even higher 3 dB frequency may be desirable). Such a f

15、ilter is described with infrasonic frequency problems in Section 3.3.4. Another way to prevent the amplifier from prematurely activating its protection systems and to protect induc- tive loads from large low-frequency currents is to con- nect a 590 to 708 F nonpolarized capacitor and 4-ohm, 20-watt

16、resistor in series with the amplifiers out- put and the positive (+) lead of the transformer. The circuit shown below uses components that are avail- able from most electronic supply stores. Fig. 3.14 Inductive Load (Transformer) Network 4-ohm, 20-watt Resistor 590 to 708 F Capacitor 120 VAC, N.P. +

17、 Inductive Load + From Amplifier Output Macro-Tech 600/1200/2400 Power Amplifiers Page 18Reference Manual 3.3.6 Additional Load Protection Macro-Tech amplifiers generate enormous power. If your loudspeakers do not have built-in protection from excessive power, its a good idea to protect them. Loud-

18、speakers are subject to thermal damage from sus- tained overpowering and mechanical damage from large transient voltages. Special fuses can be used to protect your loudspeakers in both cases. Two different types of fuses are required for thermal pro- tection and voltage protection. Slow-blow fuses a

19、re usually 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 Littlefuse 361000 series are used to protect loudspeak- ers from large transient voltage

20、s. The nomograph in Figure 3.15 can be used to select the properly rated fuse for either type of loudspeaker protection. Fig. 3.15 Loudspeaker Fuse Nomograph There are basically two approaches that can be taken when installing fuses for loudspeaker protection. A com- mon approach is to put a single

21、fuse in series with the output of each channel. This makes installation conve- nient because there is only one fuse protecting the loads on each output. The main disadvantage of this approach becomes obvious if the fuse blows because none of the loads will receive any power. A better approach is to

22、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. Thi

23、s means that your loudspeakers will tend to have better protection when the woofers are protected by slow-blow fuses and high-frequency drivers are protected by high- speed instrument fuses. 3.4 AC Power Requirements All Macro-Tech amplifiers are shipped with an appro- priate line cord. When possibl

24、e, use a power recep- tacle on a dedicated circuit and always make sure that it can supply the correct voltage and curent. We do not recommend operating your amplifier on voltages greater than 10% above or below the units rated volt- age. For example, if your amplifer is rated for 120 VAC, the line

25、voltage should not exceed 132 VAC. See Sec- tion 7 for power requirements under a variety of condi- tions. All specifications in this manual were measured using 120 VAC, 60 Hz power, unless otherwise noted. Speci- fications were derived using a voltage that is accurate to within 0.5% with THD less t

26、han 1.0% under all testing conditions. Performance variations can occur at other AC voltages and frequencies. In addition, line regula- tion problems directly affect the output power from the amplifier. Macro-Tech 600/1200/2400 Power Amplifiers Page 19Reference Manual 4 Operation 4.1 Precautions Mac

27、ro-Tech amplifiers are protected from internal and external faults, but you should still take the follow pre- cautions for optimum performance and safety: 1. Improper wiring for Stereo, Bridge-Mono and Parallel-Mono modes can result in serious oper- ating difficulties. Refer to Section 3.3 for detai

28、ls. 2. WARNING: Do not change the position of the stereo/mono switch unless the amplifier is first turned off. 3. CAUTION: In Parallel-Mono mode, a jumper is used between the red (+) Channel 1 and 2 output binding posts. Be sure to remove this jumper for Stereo or Bridge-Mono mode, otherwise high di

29、stortion and excessive heating will definitely occur. Check the stereo/mono switch on the back panel for proper position. 4. Turn off the amplifier and unplug it from the AC mains before removing the PIP card. 5. Use care when making connections, selecting sig- nal sources and controlling the output

30、 level. The load you save may be your own. 6. Do not short the ground lead of an output cable to the input signal ground. This may form a ground loop and cause oscillations. 7. Operate the amplifier from AC mains of not more than 10% variation above or below the selected line voltage and only the sp

31、ecified line frequency. 8. Never connect the output to a power supply out- put, battery or power main. Such connections may result in electrical shock. 9. Tampering with the circuitry by unqualified person- nel, or making unauthorized circuit changes invali- dates the warranty. Remember: Crown is no

32、t liable for damage that results from overdriving other system components. 4.2 Indicators The amber Enable indicator is provided to show that the amplifier has been turned on (or enabled), and that its low-voltage power supply and forced-air cooling sys- tem are working. It does not indicate the sta

33、tus of the high-voltage power supplies. For example, the Enable indicator will remain lit during unusual conditions that would cause the amplifiers protection systems to put a Fig. 4.1 Indicators high-voltage power supply in “standby” mode (see Section 4.3). The amber ODEP indicators confirm the nor

34、mal op- eration of Crowns patented Output Device Emulation Protection circuitry. During normal operation, they glow brightly to show the presence of reserve thermal-dy- namic energy. They dim proportionally as the energy reserve decreases. In the rare event that there is no reserve, the indicators t

35、urn off and ODEP proportion- ally limits the drive level of the output stages so the am- plifier can continue safe operation even when conditions are severe. (For a more detailed description of ODEP, see Section 4.3.1.) The ODEP indicator for the affected channel will turn off if a high-voltage powe

36、r supply is put in “standby” mode, a high-voltage power supply fuse (or breaker) blows, or a transformer activates its thermal protection circuitry (see Section 4.3.2). Both ODEP indicators turn off if the amplifier loses AC power, the power switch is turned off or the low-voltage power supply fuse

37、blows. The green Signal/IOC indicators show signal pres- ence, distortion and input overload. As signal presence indicators, they flash with normal intensity in sync with the output audio signals. As IOC (Input/Output Com- parator) indicators, they flash brightly if there is any dif- ference between

38、 the input and output signal waveforms greater than 0.05%. Because transient distortion hap- pens quickly, a 0.1 second “hold delay” keeps the indi- cators on long enough to be easily noticed. The IOC function essentially provides proof of distortion-free per- formance. As input overload indicators,

39、 they flash brightly with a 0.5 second hold delay to show that an input signal is too large and must be clipped at the in- put. Note: The Channel 2 IOC indicator will remain lit when running in Parallel-Mono mode. Under abnormal conditions where one of the amplifiers high-voltage power supplies is t

40、emporarily put in standby mode, the Signal/IOC indicators will stay on with full brightness. They will resume normal operation when the amplifier is no longer in standby mode. Macro-Tech 600/1200/2400 Power Amplifiers Page 20Reference Manual The table in Figure 4.2 shows the possible states for the

41、ODEP and Signal/IOC indicators. It also describes the conditions that may be associated with the different in- dicator states. The Enable indicator will be off with the first indicator state, “There is no power to the amplifier.” All other conditions in the table will occur with the En- able indicat

42、or turned on. It is important to note the pos- sible states of the indicators in the rare event that you experience a problem. This can greatly aid in deter- mining the source of problems. Please contact your lo- cal Crown representative or our Technical Support Group for futher assistance. Fig. 4.2

43、 Macro-Tech ODEP and Signal/IOC Indicator States Macro-Tech 600/1200/2400 Power Amplifiers Page 21Reference Manual the loads and prevent oscillations. The unit resumes normal operation as soon as the amplifier no longer detects dangerous low frequency or DC output. Al- though it is extremely unlikel

44、y that you will ever activate the amplifiers DC/low-frequency protection system, im- proper source materials such as subsonic square waves or input overloads that result in excessively clipped input signals can activate this system. The amplifiers fault protection system will put an am- plifier chan

45、nel in standby mode in rare situations where heavy common-mode current is detected in the channels output. The amplifier should never output heavy common-mode current unless its circuitry is damaged in some way, and putting a channel in standby mode helps to prevent further damage. The amplifiers tr

46、ansformer thermal protection cir- cuitry is activated in very unusual circumstances where the units transformer temperature rises to unsafe lev- els. Under these abnormal conditions, the amplifier will put the channel of the affected transformer in standby mode. The amplifier will return to normal o

47、peration after the transformer cools to a safe temperature. (For more information on transformer thermal protection, refer to the following section.) 4.3.3 Transformer Thermal Protection All Macro-Tech amplifiers have transformer thermal pro- tection. It protects the power supplies from damage un- d

48、er the rare conditions of transformer temperatures rising too high. A thermal switch embedded in each transformer removes power to the channel if there is excessive heat. The switch automatically resets when the transformer cools to a safe temperature. It is extremely unlikely that you will ever see

49、 a Macro-Tech amplifier activate transformer thermal pro- tection as long as it is operated within rated conditions (see Section 6, Specifications). One reason is that ODEP keeps the amplifier working under very severe conditions. Even so, higher than rated output levels, excessively low impedance loads and unreasonably high input signals can generate more heat in the trans- former than in the output devices. These conditions can overheat the transformer and activate its protection sys- tem. Macro-Tech amplifiers are designed to keep working under conditions where other amplifiers woul