What Pryo is stating that the Magenpans are mostly resisitive in their impedance compared to that of conventional loud speakers Convenetial speakers impedance has a large reactive component. That means that the power delivered to the Magenepans will have a greater pecentage applied to the actual resistive load than that of the Polks. That same power when delivered to the Polks will have a larger component waisted on the reactive part of the speaker impedance and less power delivered to the resistive part. Its the resistive component of the impedance that directly influences how loud the speaker will play.
Just because an impedance curve is flat does not mean the load is not reactive.
The Magnepans, have a fine ribbon bonded to a thin mylar film. There is a perforated grid containing permanent magnets. The signal from the amplifier passes though the ribbon film. Since the voltage is not constant, it varies with the modulation of the signal, the current is not constant, and this results in a modulated magnetic flux which interacts with the steady flux of the permanent magnets to modulate the diaphragm. So it is a reactive load and there will be a phase angle between voltage and current.
These speakers have a flat impedance curve, so they will actually present a somewhat lower impedance to the amp. Now the effect of the phase angles does not show up in the impedance curves.
The problem arises in that because of the phase angles you have the phenomenon of true and apparent power. The true power will be what is consumed, however the current for the apparent power has to be provided by the amp without clipping. In other words at parts of the cycle power consumed is higher than you would think and at other parts of the cycle power is given back. That is in the nature of reactive AC circuits. The difference in true power and apparent power is dependent on the phase angle between voltage and current. The wider the phase angle the greater the current required to provide the apparent power requirement.
The phase angle of speakers is seldom specified. There has been a lot of discussion over the years in the professional journals about coming up with a spec that truly quantifies the difficulty the load a given speaker presents to an amp. In fact realistic ways of doing this have been developed, but this is heavily resisted by the loudspeaker industry for obvious reasons.
The MMG speakers are actually quite insensitive. They are specified at 86 db 2.84 volts 1 meter, which would put them at only 83 db 1 watt 1 meter.
Magnepans have always been known to be inefficient as the there is greater space between the conductor (ribbon) and the magnets than in voice coil type speakers.
Since they have a flat four ohm impedance curve, but by the nature of their design, the load must be to some degree reactive, the current required at parts of the cycle will be higher than suggested by ohms law.
That is why Magenplanar loudspeakers do really require a beefy amp. I have heard the Mggies often and like them. They do sound their best when driven by expensive amps. After all is said and done though they are a poor man's electrostatic. In my view good full range electrostatics are superior. However these are expensive complicated, more prone to failure and present difficult capacitative loads to amps.
