One Monoblock or Two?

"First, what do you call a 'difficult load'? "

- High values of "Equivalent Peak Dissipation Resistance" or EPDR which 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.

"The high frequencies need much less power than the lows,"

It is correct assumption with some speakers and wrong with others. For example, most of electrastatic speakers high
frequencies required 7-15 times more of EPDR (see above for definition) then low frequencies.

All The Best
Simon

EPDR takes into account the reactance of the load.
My preference is to go to 'root' and use powerfactor. I also like the power cube way of measuring amp output by taxing the amp with inductive, capactive and resistive loads from 1->8 ohms, and +-60 degrees.....You measure the extremes and the amp is good 'under' the limits measured. The graphic gives a response range for the amp which is intuitive and easy to understand.

Electrostats may just be a wacky hi phase load at higher frequencies. Fortunately, those frequencies in normal music require the least power.

http://www.audiograph.se/Downloads/PowerCube_12p_brochure_complete.pdf

Also, most speakers when measured (why bother? seems to be the attitude) are only measured for impedance, which from the above and EPDR, is only part of the story.
I have been a big fan of a different presentation of the same data in the form of the Smith Chart.
I understand the RF guys like this.(microwave?)
Anyway, it also, when scaled properly, makes perfect sense for speakers, as well.

The 50:50 point for power is AROUND 350 hz, based not on speaker need, which you can't know in advance..or predict for YOUR speakers, but simply on acoustic power. Add more as you see fit, based on how wacky the speaker load is.

What got me thinking about this was a long time ago, the original Braun Tri-amps which had 100 watts RMS per speaker divided 50:35:15 with unknown (to me) crossovers.

Article on the Smith Chart presentation.
http://www.hometheaterhifi.com/component/content/article/228.html

Doing a search for"Equivalent Peak Dissipation Resistance" gave quite a few hits. I was surprised at the number.
In looking thru the first 4 or 5 I came across the stereophile article. In it, the author said something about JA liking the measure, and wanting to use it but not really having the time to implement it.
I suspect it would take some data entry and real number crunching to get it useful. Not to mention the huge database of speakers which already had been measured.
Than, the education part would start. People INSIST that low impedance = 'bad'.
Some speakers, even low sensitivity are tube friendly. I was reading about some guy who had Harbeth LS3/5 copies and some fairly low powered tube amp. I'm guessing it worked like a charm.
People are tough to convince. I'm in that category, too, i'll admit....most of the time.

And, in looking thru another aritlcle, they showed phase / impedance data for several speakers, including an electrostat. OUCH. The trifecta hit. Low impedance, high phase angle AND low sensitivity. How can you top that?

In looking this over, I'm willing to see if I can make sense of this new measure, as soon as I start seeing data.

I'd like to know why speaker designers don't wise up to their amp killing ways? I've been lookiing at measured data for quite a while and while I don't have a 'quality number' to characterize a speaker, big impedance dips at hi phase angle points have always been a red flag...

I urge any reader to look at the Smith Chart and see how this measured data can be put on a single lined chart.....and have it make sense.....