how does current work in an amplifier?

Athmasphere, I have a question for you.

First, background: In this discussions most of participants when refer to impedance mean only its modulus.

from Simon Thacher of Spectron paper
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... loudspeaker loads comprise complex impedances with both resistive and reactive (capacitive and inductive) components. Such impedance can be depicted as a vector with its magnitude (modulus) and angle (phase), and both vary with frequency. In general, the voltage and current waveforms, in complex impedance load, are out of phase with each other and therefore, to characterize accurately a speaker's load impedance, both modulus vs frequency and phase vs frequency plots must be known. Frequently, the phase angle is much more crucial to the speaker load than the modulus alone

To deal with this phenomenon, Keith Howard ("How Much Power Do I Need?" Hi Fi News July-Sept, Nov 2007 ) introduced the figure of merit he has labeled Equivalent Peak Dissipation Resistance (EPDR). This is, simply, the resistive load that would give rise to the same peak power device dissipation as the speaker itself. Using EPDR as a figure of merit, the speakers can be compared directly with each other.

Sorry for tbe long introduction: Question is simple: do you agree with Keith Howard figure of merit (EPDR) and if so why speaker manufacturers are not utilizing it, and amplifier manufacturers are not demanding it?

Thank you.

Atmas,

I don't think the SS devices of 40 years or so ago can be compared apples to apples with their tube predecessors.

True, probably that SS was cheaper power technology than tubes, but most good vendors tended to maintain and add value with new features that could now be offered and still make a profit.

There is nothing evil about progress. It usually involves doing things more cost effectively in conjunction with providing greater overall value.

Its many years later now. Tubes have their advantages and disadvantages just like everything else. Their disadvantages overall led to their falling out of favor. Not to say that they are not capable of doing unique things in regards to sound quality overall still these days, but there is more than one way to skin a cat....

Atmasphere, with all due respect there were other incentives such as convenience and reliability amongst others.

Unsound, certainly! I think we can add to that, heat, as well (although I know of transistor amps that run as hot as tubes). We are talking about a very traditional set of tradeoffs when these aspects are brought into the conversation: convenience vs performance, an issue you see in nearly every field of endeavor.

Mapman, Of course semiconductors have improved immensely since the beginning of the art! I'm not saying there is anything wrong with 'progress' in of itself. I'm just pointing out a simple fact.

Dob, I like the idea of EPDR; like other specs it does not appear to tell the whole story, but certainly would standardize a lot of things that can be hard to winnow from the other specs you see. IME, Magnaplanars seem to have an easy EPDR rating compared to a lot of 4 ohm speakers I have seen. This would be very apparent if such a spec were commonplace.

Atmasphere, of course many of find some ss amps offer a balance of both objective and subjective performance that is preferable. I am confident that many speaker designers welcome the opportunity to avail their design talents towards making speakers for those ss amplification attributes for the sheer performance opportunities those combinations provide.