Tannoy B475 사용자 설명서

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CABLE RUN 
(m) 
C.S.A. OF EACH 
CONDUCTOR (mm) 
CABLE 
RESISTANCE 
Ω
Ω 
% POWER LOSS 
INTO 8
Ω
Ω LOAD
 
% POWER LOSS 
INTO 4
Ω
Ω LOAD
 
10 
2.5 
4.0 
6.0 
0.14 
0.09 
0.06 
1.7 
1.1 
0.73 
3.5 
2.2 
1.5 
25 
2.5 
4.0 
6.0 
0.35 
0.22 
0.14 
4.3 
2.7 
1.8 
8.6 
5.4 
3.6 
50 
2.5 
4.0 
6.0 
0.69 
0.43 
0.29 
8.6 
5.4 
3.6 
17.0 
11.0 
7.2 
100 
2.5 
4.0 
6.0 
1.38 
0.86 
0.58 
17.0 
11.0 
7.2 
35.0 
22.0 
14.0 
 
4. Polarity Checking 
It is most important to check the polarity of the wiring. A simple method of doing this 
without a pulse based polarity checker for LF units is as follows: Connect two wires to 
the +
ve
 and -
ve
 terminals of a PP3 battery. Apply the wire which is connected to the +
ve
 
terminal of the battery  to the speaker cable leg which you believe to be connected to 
Pin 1+ of the speaker connector and likewise the -
ve
 leg of the battery to Pin 1-. 
If you have wired it correctly the LF drive unit will move forward, indicating the wiring is 
correct. All that remains now is to connect the +
ve
  speaker lead to the +
ve
 terminal on 
the amplifier and the  -
ve 
lead to the  -
ve 
terminal on the amplifier. If however the LF 
driver moves backwards, the input connections need to be inverted. 
If problems are encountered, inspect the cable wiring in the first instance. It should 
also be noted that different amplifier manufacturers utilise different pin configurations 
and polarity conventions. If you are using amplifiers from more than one 
manufacturer, check the polarity at the amplifiers as well as the loudspeakers. 
5. Amplification & Power Handling 
As with all professional loudspeaker systems, the power handling is a function of 
voice coil thermal capacity. Care should be taken to avoid running the amplifier into 
clip (clipping is the end result of overdriving any amplifier). Damage to the 
loudspeaker will be sustained if the amplifier is driven into clip for any extended period 
of time. Headroom of at least 3dB should be allowed. When evaluating an amplifier, it 
is important to take into account its behaviour under low impedance load conditions. A 
loudspeaker system is highly reactive and with transient signals it can require more 
current than the nominal impedance would indicate. 
Generally a higher power amplifier running free of distortion will do less damage to the 
loudspeaker than a lower power amplifier continually clipping. It is also worth 
remembering that a high powered amplifier running at less than 90% of output power 
generally sounds a lot better than a lower power  amplifier running at 100%. An 
amplifier with insufficient drive capability will not allow the full performance of the 
loudspeaker to be realised. 
It is important when using different manufacturers amplifiers in a single installation 
that they have very closely matched gains, the variation should be less than +/- 0.5dB. 
This precaution is important to the overall system balance when only a single 
compressor/limiter or active crossover is being used with multiple cabinets; it is 
therefore recommended that the same amplifiers be used throughout.