|
|
此時無聲勝有聲！$ G! @7 g3 [3 P$ @
- U' A! a, ^0 W3 e : V' U; _( v9 k# m# f. n/ A0 i
0 V u5 e1 ]* Z4 P& XA typical high-impedance system is shown in Figure 1. A transformer at the power-amplifier output steps up the voltage to approximately 70 volts at full power. Each speaker has a step-down transformer that matches the 70V line to each speaker's impedance. The primaries of all the speaker transformers are paralleled across the transformer secondary on the power amplifier." N, |5 Q4 U/ s% ~9 F" ]( U
" l" e; D. o" `7 x3 D) ~0 q
ADVANTAGES OF 70V OPERATION6 G# \6 c) |4 _% p. D
As stated before, a 70V line reduces power loss due to cable heating. That's because the speaker cable carries the audio signal as a low current. Consequently you can use smaller-gauge speaker cable, or very long cable runs, without losing excessive power. Another advantage of 70V operation is that you can more easily provide the amplifier with a matching load. Suppose you're connecting hundred of speakers to a single 8-ohm amplifier output. It can be difficult to wire the speakers in a series-parallel combination having a total impedance of 8 ohms. Also it's bad practice to run speakers in series because if one speaker fails, all the speakers in series are lost. This changes the load( E5 f1 l2 ]5 [1 M% R+ L& A
impedance seen by the power amplifier.
' Y: P& |4 a* [1 {+ w& x8 U |
|
/1 
发表于 2016-8-28 17:05
收藏
淘帖
支持！
反对！
发表于 2016-8-30 23:17
