Handling a complex load by power amplifiers

[Blumlein 88]

Here is a good impedance curve to consider. From Stereophile, the curve for Soundlab ESLs. I've owned some and it is accurate. Lots of phase and impedance variations with frequency. A tube amp with a hefty one ohm output impedance will not matter at lower frequencies. Those peaks off the top of the chart go over 30 ohms. OTOH, up near 20 khz where the speaker has the phase rotation of nearly a capacitor and an impedance of an ohm (depending upon speaker settings it can be .5 ohm) the output impedance will cause the speaker output to droop significantly. With such a speaker load a tube amp and low output impedance class D amp will sound different. Due to the resulting FR differences.

 

[Tha RF & AudioMaestro]

Yes..... There is A STANDARD Wich is ( o,1 uF/8 ohms )
Wich is suposed to be the most provokative combination for most of the push-pull Amp Topology's suposedly it's capacative reactance combines with the zobel coil witch is in the output of allmost every amp in the world to protect against EXACTLY CAPACATIVE Loads, to produce nasty ringing and other bad things and if there is a big/large feedback loop it tends to mess up thjat to.... Allthough i have seen tests with uP to 2,2uF/8 ohm, it seems the capacitance around o,1 - o,22 uF is the worst for most amps....