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In Reply to: RE: Measurements vs. Reviewers posted by mark.korda@myfairpoint.net on August 18, 2015 at 10:07:49
I just read this review once it was posted online at stereophile and I find it another example of measurements and reviewers not agreeing.
In this case though I find it strange that JM has such high praise for the speaker because it REALLY has no bass whatsoever...subwoofer mandatory, IMO, is pretty lumpy measuring overall with a not so nice peak at 1Khz and a suspicious crossover region (will likely sound a bit laid back I would think as the presenc region is suppressed.).
Also, even though it is crossed over high at 5khz, why no first-order and time-alignment, like Reference 3a MM De Capo Be? Even though the Ref 3a doesn't measure great it at leasts make good bass and is time coherent...a reasonable tradeoff in most cases for a less than perfect FR.
In the end JA is puzzled by the praise. I auditioned at length the more upscale WB Arc a few years ago and found it far to polite to deliver music realism.
This review strikes me more of a fanboy for WB position rather than a critical review. How could JM listen to full-range music with this speaker?? It is -20db at 40Hz and -6 db at 80Hz. Very much like some Infinity Modulus speakers I had many years ago (that were great when lashed to an equally good subwoofer).
Finally, there is the price...ridiculous for this performace! Since a sub is mandatory I would add another $2K to the sticker at least for a good Velodyne or similar.
Follow Ups:
I'll bet the crossover region looks and sounds much flatter in the far field. If you look closely at the vertical dispersion plot, the on-axis response pattern from 1-10KHz is opposed by roughly the opposite pattern off-axis in the vertical dimension. The rising response on-axis from 400Hz-1KHz is also opposed by a falling response off axis in the horizontal plane. The 1KHz peak should certainly be audible because there seems to be a resonance, but I would expect this speaker to sound a lot flatter in-room than you might guess if you look only at the nearfield response on-axis.
This review is incomplete without an in-room measurement in JM's listening room. That would not only shed light on whether the midrange & treble power response sums flat, it would also shed light on how the passive radiator couples with the wall behind it, which was only 12" away in JM's preferred placement. Without that, I find it hard to interpret JM's listening impressions.
This situation reminds me a little of the Sfojn the Clue review. That speaker was designed without baffle step compensation for placement against a wall, but it wasn't measured that way. Also, the Clue had some massive +/- 10 dB swings in the nearfield on-axis response which were opposed by the opposite pattern off-axis. That review sorely needed an in-room response measurement to back up Herb's findings. I basically just dismissed Herb's listening impressions since there was no way to know whether the speaker was working as intended. Maybe Herb just likes a fat bottom end.
> even though it is crossed over high at 5khz, why no first-order and
> time-alignment, like Reference 3a MM De Capo Be?
The original version of the Square One did have first-order crossover
filters. But you can't achieve true time alignment without a sloped-back
front baffle.
John Atkinson
Editor, Stereophile
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.
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.
@JA.
Sloped Or stepped baffle for proper time alignment , while both time align , sloping shifts image height downwards. John , your comment regarding drilling and sticking the measuring mic into the enclosure has peaked my interest , i have a few test modules i can try this with using LMS....
@Morricab,
Funny you should say such Morri, its the same way i feel about the reference 3a fan bwoys, measures poorly and audible , then again its audio , freedom to enjoy it all ...
Regards
Ref 3a, yeah I like the speakers because they sound very coherent...like a single driver without the weirdness of most of them. Clarity is superior to a lot of other box speakers too. That said, I like my Odeons more...
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