I watch that video, it is interesting. But I have a question. Is it really the speaker drawing power? I don’t think the speakers draw power, but it is the amp pushing power, right?The amp makes the power and the speaker draws the power it can based on its impedance and the voltage that the amp makes. So for a given voltage, if the speaker draws one watt and its impedance is 8 ohms, into 4 ohms it will draw two watts if the amp is making the same voltage. Its a mathematical relationship.
I have a question. if we play the same music, volume knob at the same level, to a more sensitive speaker, will it display that it is pushing the same 750W power?
Regarding the more sensitive speaker question, if the impedance is the same the power will be the same. Now the thing about more sensitive speakers is if the impedance is 8 ohms or more, the amp will not have to work as hard to make the same sound pressure level and usually will make less distortion. If it makes less distortion, it will sound smoother and more detailed (since distortion can mask low level detail). Now solid state amps in general tend to make higher ordered harmonic distortion compared to tubes, and so tend to sound bright, even though that distortion is fairly low. The reason we perceive it as bright is because the ear uses higher ordered harmonics to sense sound pressure and is thus keenly sensitive to their presence. It is this simple fact that is why tube amps are still around.
The reason solid state amps tend to sound bright is that usually they don't have *enough* feedback (some get around this by having none at all). Its pretty hard to design a circuit that allows for really high amounts of feedback (+35dB). So most simply don't. The result is that the application of the feedback itself, while suppressing some distortions, actually adds some of its own (which is almost entirely higher ordered harmonics; that which is not is IMD and both are very audible). Unless you can get over that 35-40dB range, this will be a problem, and its been a problem in solid state design since the inception of the transistor.
To get around this problem, many solid state amp manufacturers have resorted to a simple technique called 'lying'. But our ears don't lie- we've been hearing brightness and harshness in solid state amps for the last 60 years; that is why tubes and tube amps are still around decades on from being declared 'obsolete'.
