Home Speaker Asylum

General speaker questions for audio and home theater.

Methodology problem imo

The methodology used is not dipole-friendly, and is even less dipole-panel/box-woofer-hybrid-friendly. Let me explain:

One of the main benefits of a dipole speaker is its spectrally-correct backwave energy that, with proper setup, arrives at the listening position after a time delay of ballpark 10 milliseconds or more (this figure corresponding with positioning the speakers about 5 feet in front of the wall). My understanding is that the area behind the speakers in the Harman listening room is absorptive, so dipoles get no benefit from their backwave energy.

Also, the spectral balance of a woofer/panel hybrid like the Martin Logan is dependent to a large extent on listening distance. This is because you have a point-source-approximating woofer combined with a line-source-approximating panel. Sound pressure level falls off by 6 dB for each doubling of distance from a point source, but only by 3 dB for each doubling of distance from a line source. This is not just theoretical - it happens in the real world, I measured it in my living room on SoundLab Dynastats (which are conceptually very similar to the Martin Logans). Now you might say that this is a design flaw of the configuration, and I suppose it is, but it also means that, in order to see what a woofer/panel hybrid has to offer, you gotta pay attention to getting the setup right.

Kinda like evaluating Audio Note speakers on high stands set way out in the middle of the room... that setup would not show what they have to offer. Even moreso with improperly set up dipole/woofer hybrids.

So I really do not think the Martin Logans were given a fair chance to show what they could do. And it's too unwieldy to completely change the test procedure for "special case" speakers like these, so I don't know of a practical solution, but I'm a little surprised that Toole et al apparently failed to understand their specialized setup requirements. Or maybe they do understand them, but figure no one else does, and so they continue to use the Martin Logans as an example of good correlation between objective measurements and subjective preference. Which they are in this case.

And I think THAT was Toole's main point, rather than "stats suck" or something like that.

Duke

Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.



Edits: 05/30/17 05/30/17 05/30/17

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