Per Audioguru,

DC in a speaker produces no sound, only heat.

Yes...
The rated power of a speaker is with a sinewave input, not DC and not a squarewave.

Yes....
If an amplifier can produce a sinewave with a RMS level of 4V into an 8 ohm speaker then the power in the speaker is 2W. But if the amplifier is overdriven and clips badly producing a squarewave with the peak-to-peak voltage (11.3V) the same as the 4V RMS sinewave then the power in the speaker is doubled to 4W because the distortion harmonics produce the same amount of power as the fundamental sinewave. The speaker is still being cooled because the voice coil is moving back and forth but with DC it does not move.

Yes, the voice coll must be provided movement, else it overheats - thus my previous statement (from ‘The Illustrated Ductionary of Electronics’) still holds ....

 

My copy of ‘The Illustrated Dictionary of Electronics” (fourth edition) states that a fluctuating current is also referred to as a composite current, “a current containing companants of both AC and DC, i.e. an alternating current superimposed on a direct current”..... does this not describe the signal to a speaker??....

Just read your last - yes of course a voltage componant IS always present, but not the dominate componant via the output stage.... Correct? (Yes -No??)

What you state makes no sense whatsoever. Neither voltage or current dominates over the other. They are both equally present.

 

When the signal generated by the amplifier is AC coupled there is no DC.

Most hi-fi amplifiers quote a specification of 20-20kHz frequency response.
If the signal is band-limited with a low frequency cutoff at 20Hz then theoretically there is no DC.
If there is DC output at the speaker terminals then the bridged output is out of balance and will damage the loudspeaker.

 

By the way, tube amps don't clip in the same way solid-state amps clip.
Tube amps inherently compress the signal and you get a softer form of distortion instead of harsh square wave output.
This is the main reason tube amps are preferred by some musicians.

 

Please correct these following two statements:

1) an amps input section primarily amplifies voltage. (Yes - No?) ....please, yes or no ...

2) an amps output stage primarily matches amp current (by amplifying) to match speaker current requirements.
(Yes- No?)...

IF statement 2 is correct then current is dominate within the output stage, no??

FWIW, I think we are just splitting an atom ....

 

Technically speaking, an amp doesn't amplify anything.
An amplifier is like a control value, tap, faucet, spigot, cockstop, etc. where a small about of effort is needed to turn on a bigger tap.

 

I think I see where your problem lies. You are trying to categorize everything as either black or white. If it isn't black then it must be white.
You are not going to arrive at acceptable answers if that is your world view.

 

My ‘World View’??....... ok, I’ll cry Uncle, you ‘WIN’.....!!
(abbreviated obscenity removed by moderator)

So sorry but I didn’t sign up for attitude .....

 

1) an amps input section primarily amplifies voltage. (Yes - No?) ....please, yes or no ...

Yes, an audio amp increases the voltage value of the audio signal from input to output (which is the usual electronic meaning of "amplify").

2) an amps output stage primarily matches amp current (by amplifying) to match speaker current requirements.
(Yes- No?)..

No.
The output current is determined by the output voltage divided by the speaker impedance at the frequency of the signal.
(Do you understand Ohm's law?).
There's no "matching" involved (whatever that means ).

IF statement 2 is correct then current is dominate within the output stage, no??

That question in a bit of a non-sequitur.
Voltage and current are two aspects of electricity in a circuit.
What do you mean by "dominate"?

 

Don't get hung up on this current vs voltage thing.
Ohm's Law applies.

I = V/R
V = I x R

The output impedance of the amplifier has to match that of the load for maximum power transformer.

The impedance of a typical loudspeaker is 4Ω or 8Ω.
If you pump 24V into 8Ω the current will be 3A. The power delivered is 72W.
If you reduce the resistance to 4Ω the current will be 6A. Power delivered is 144W.

Designing an amplifier with 4Ω output impedance is not an easy thing to do. If the output impedance is 10Ω you are not going to get any where near 144W power output.

If the output impedance is 4Ω you would need 48V supply voltage to get 144W.
If the output impedance is 10Ω you would need 84V supply voltage to get 144W.

 

The output impedance of the amplifier has to match that of the load for maximum power transformer.

That's a common misinterpretion of the maximum power theorem.
A typical trick question on an exam after learning about the theorem is "What does the source impedance need to be to deliver maximum power to a 50Ω load.
The answer often given is 50Ω, but the correct answer is zero ohms.
The theorem states that the load impedance must equal the source impedance for maximum load power but (if you think about it) the converse is not true.

Designing an amplifier with 4Ω output impedance is not an easy thing to do.

That's only done for some tube (valve) amps using the proper turns-ratio in the output transformer to match the tube impedance to the speaker impedance.
Most solid-state audio amps have an output impedance well under an ohm.