wwgmm 在 2004-2-27 23:58:35 发表的内容
有个问题一直搞不明白！
阻抗值越小，需要推动的电流就越大！
但是比如一个功放推 8Ω的音箱最大能输出100W
推4Ω的时候输出功率却几乎或完全大了一倍！ |
Theoritically it is right if a transistor amplifier was designed to drive very low
loadint (say 2 Ohm) but it cost a lot more to build.
Some amplifiers cannot double the poer even the loading impedance drop from 8 Ohm to 4 Ohm. For example, ay 8 Ohm 100W, but at 4 Ohn it only
gives maybe 120W. This is due to the power transistor plus the power
supply cannot provide such high current at this low impedance. This kind of amplifers will loose contorl to the speakers.
Only high current design have good damping at all impedance say from
2 Ohm to 16 Ohm.
Tube amplfier with output transformers and impedance taping does not
apply to this as tube amplifier is
CONSTANT CURRENT DESIGN
while the OTL transistor amplifiers are
CONSTANT VOLTAGE DEVICE
Hope this is clear to you all.
Again, sorry folk, I can't type Chinese.