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In Reply to: RE: Vince Bruzesse on Totem Cabinet Design posted by Schlep on July 07, 2017 at 06:56:35
I was fascinated with the Element series at a New York show a few years ago. I was especially interested that they said they used a Bessel function for tuning the bass response which according to what I've read is a total pain to achieve in a reflex box since it needs a driver with careful control of the Qts of the driver to do passively.
Wilson Benesch has been using Bessel alignment for many years, since the early 2000s I think. The Totem Element design has several things in common with Wilson Benesch. There is the in-house designed mid-bass driver running near-full range up to 5 KHz with no external crossover parts, with a first order acoustic roll-off above that, a soft dome tweeter with a somewhat higher than usual fs and a single cap to roll it off below 5 KHz, and a BE4 bass-reflex alignment. All of these design choices are made in the name of transient performance.
I used to own Wilson Benesch speakers and they were subjectively fast sounding, with notes starting and stopping very quickly and cleanly. They were also very good at soundstaging and had unusually good dynamics for their size. I hear some of the same characteristics in the Totem Element Fire, with the exception that the top octave of the W-B speakers is a bit dark whereas the Totems are a bit bright.
But this design approach sacrifices frequency response for the sake of better transient response. And to my ears, the sacrifice is too great. There are two obvious audible problems with the two-ways. First, the high crossover frequency results in mismatched dispersion, and I couldn't find a toe-in angle that gets the treble balance at the listening position right. Second, there's no baffle step compensation, so either the lower midrange is too weak (W-B) or the upper midrange is too strong (Totem).
Ah yes. . . the isobaric woofer arrangement. I wish I had heard the Mani 2s, but have not had the opportunity. I would have loved to hear how the theory translates to the the experience.
On a similar note Elac's new $2500 monitor, the AS-61 / Andante, is using a passive radiator in front of a smaller active woofer. Mids / Tweet is coaxial on top. Very curious about this one as well.
Sorry, this has nothing to do with Isobaric which is just a way to substitute efficiency for a smaller cabinet. I was referring to the element speakers. I was told at the show they had a Bessel(minimum time delay roll off). This is fairly easy to do in a closed box by adjusting box volume to fit a driver. But in a reflex the driver has to have specific Thiel/Small values otherwise there's no way to get a Bessel function no matter what changes are made to the box size and port. But,
of course, Totem makes their own drivers for these speakers.
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