我们都知道,电子管的电功率和音量不成正比关系,也就是说电功率减小一倍,声功率减小并不多。这就给我们选择衰减器带来了很大的不便,不同的功放音量不完全相同,而衰减器只能按电功率衰减来标定,如何建立电功率和音量之间的一个关系,如何利用一些简单的方法就知道应该选多大的衰减器。下面来看这个表格
40 watts is 94% as loud as 50 watts.
30 watts is 86% as loud as 50 watts.
25 watts is 81% as loud as 50 watts.
22 watts is 78% as loud as 50 watts.
20 watts is 76% as loud as 50 watts.
18 watts is 74% as loud as 50 watts.
15 watts is 70% as loud as 50 watts.
12 watts is 65% as loud as 50 watts.
10 watts is 62% as loud as 50 watts.
9 watts is 60% as loud as 50 watts.
8 watts is 56% as loud as 50 watts.
7 watts is 55% as loud as 50 watts.
6 watts is 53% as loud as 50 watts.
5 watts is 50% as loud as 50 watts.
4 watts is 47% as loud as 50 watts.
3 watts is 43% as loud as 50 watts.
2 watts is 38% as loud as 50 watts.
1 watt is 31% as loud as 50 watts.
3/4 watt is 28% as loud as 50 watts.
1/2 watt is 25% as loud as 50 watts.
1/4 watt is 20% as loud as 50 watts.
1/10 watt is 15% as loud as 50 watts.
50mW is 13% as loud as 50 watts
20mW is 10% as loud as 50 watts.
10mW is 8% as loud as 50 watts.
5mW is 6% as loud as 50 watts.
这里推荐一个方法。将你的功放音量调小到你可以接受的程度,当然音质可能已经很差了,但你可以了解可接受的声音大小占总音量的百分比,根据上表,你来查出需要的电功率衰减量。 比如: 你的机器是30瓦,你调到1/2音量才能接受。要获得音质较好同时音量又能接受的声音,电功率必须衰减到3瓦,每-3分贝,功率衰减一半,那就是要衰减7 db左右才能达到目的。 |