Amplifier Speed

Onhwy61 and Sean...Although this "transit" or "propagation" time is not quoted in specs, and I for one have not measured it (although it would be easy to do) it cannot amount to more than a few degrees of phase shift for a 20 KHz signal, or else global feedback would be impossible.

Sean, you have a dual-trace scope. Why not give us some data.

The time it takes for the signal to travel from the input to the output would be dependent on the length of the circuit and the velocity of propogation through the circuit. This is technically referred to as Td, hence my comments about the lack of disclosure of this spec from most manufacturers. Sean
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Thanks for the responses. I was asking about the speed of the electron/signal.

How many manufacturers actually quote Td ( Time delay ) for a component? I've only ever seen one company ever provide this spec. Sean
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If you are talking the speed of electron/signal,it's not an issue at all.

Transient respond/speed is a completely different story.

Slew rate (or rise time) is of no consequence for the LF audio amp in a biamp setup because the LF signal from the crossover has no steep wavefronts to be followed.

In my opinion it would absolutely be an issue but perhaps not as you may anticipate regarding timing, tempo, and signal arrival.

A 4 minute and 36 second musical track will still take exactly 4:36 regardless of the matching or mis-matching of amps.

If you had a 'fast amp' for the mids and highs, you would simply have potentially a more sluggish and ill-defined sounding bass region. Or vice versa.

The fast really refers to the amp's agility and speed to go from a dead silence to an initial attack, esuing decay, and picking up hopefully every little bit of nuance and inter-transient silence in between.

As far as I know, the slower amp's signal will arrive at roughly the same time, but it most likely will skip some to much of the nuances and inter-transient silence that the other amp will pick up.

So in the end, the slower amp will sound as though the tempo is slower even though it's the same. But only because it's running the musical information together.

In my limited experience, most amps are not fast.

Therefore, if you have the wherewithall to purchase what is known as a fast amp, I'd do so without hesitation. You're system will be that much better off. Assuming the fast amp does not have other significant deficiencies.

-IMO

In order for global feedback to work at all, propagation time through an amp must be a few degrees of phase angle for a 20 KHz signal. I suspect that there is little difference between amps.

Phase shift in the crossover would be more significant.