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In Reply to: RE: What to make of John Marks review of the WB Square One? posted by John Atkinson on August 24, 2015 at 03:58:01
Well I certainly don't know what to make of this review. Marks says the speaker starts to respond down at 44.1 hz, the manufacture claims 45 hz but with no +/- db (my headphones go down to 30 but only at 1 watt) and the measurements show the speaker is down about 15 db from 2 kHz, about 20 db from that awful peak at 1 kHz. That's a falloff of 95% to 99%. The output from the passive radiator and the ports add about nothing to the woofer itself. Output at 45hz is so low if it exists at all that for all practical intents and purposes it should be next to inaudible. But Marks not only says he hears it, with a better amplifier it seems to add another octave lower. Is the speaker actually doubling? What is its THD versus SPL at 45hz?
So which is wrong? Is Marks' opinion worthless? Are the measurements worthless? Or are both worthless? They miss each other by a country mile but there is no explanation why. I think I can do better for a tenth the money with a kit from Parts Express. It's reviews like this, confusing, incoherent and self contradictory, incomplete, ridiculously flattering that I not only don't subscribe but rarely read it on the internet for free.
Follow Ups:
Yep, that is why I brought it up in this thread.
Atkinson got it wrong about "phase coherence." The difference in the group time delay between drivers can be compensated for by an appropriate digital time delay for the signal going to the tweeter (requires a separate amplifier.) Even without time delays the relative group delays can be reduced by making the tweeter heavier and the woofer lighter.
That being said, the whole idea is stupid because even when they are vibrating in phase, unless they are concentric and have the same center of propagation, there will be interference patterns due to geometric considerations. It's like dropping two rocks in a pond and they hit the water at the same time but not in the same place. This is wave mechanics 101. The only way to test for the audibility of phase coherence is to build a speaker that is coherent but adjustable so that it is not coherent and then switch the circuits between them. Otherwise there are far too many variables to say yes or no. Fortunately this buzzword fad is history and now the industry is on to new and different silver bullets.
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