Equivalent peak dissipation resistance, EPDR

[John Mulcahy]

Back in 2007 Keith Howard proposed a measure he called Equivalent peak dissipation resistance, EPDR, to reflect the way the phase angle of a speaker load increases the peak power dissipation in the output transistors of a power amplifier beyond what might be expected from the load modulus. The EPDR value is the resistance that would result in the same device peak power dissipation as the speaker load at a given frequency. Would there be interest/value in including an EPDR plot on REW's impedance measurement graphs? Here is an example of what it looks like:

 

[Breeman]

One often reads in loudspeaker reviews, comments about "resistive" phase response of a loudspeaker being problematic to an amplifier. I never quite got around to understand the theory it. I think it would a great addition to what is already a excellent arsenal of features available in REW. Thanks for the reference.

 

[Antonio Di Motta]

The proposed EPDR measure is very interesting because it highlights the problem of phase rotation and the stress it entails on power amplifiers and to understand if this solicitation causes the intervention of the protection circuits.
Excellent measure ...

 

[Talesin]

Yes, absolutely there is interest! Many thanks!

 

[John Mulcahy]

It was implemented in V5.20 beta 46, so is available in the current beta version.

 

[zerooffset]

Hello I'm Italian. I would like to have information about EPDR. Is it the real part point-by-point of complex impedance? Sorry for my not good English

 

[John Mulcahy]

Hello I'm Italian. I would like to have information about EPDR. Is it the real part point-by-point of complex impedance?

No. The EPDR value is the resistance that would result in the same device peak power dissipation as the speaker load at a given frequency. There is more information in the Stereophile article linked above and E. Benjamin, "Audio Power Amplifiers for Loudspeaker Loads," JAES, Vol.42 No.9, September 1994 (available from www.aes.org).