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New Celestion "AxiPeriodic Driver"
New Celestion "AxiPeriodic Driver"
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Old 23rd July 2016, 06:21 PM   #11
bwaslo is offline bwaslo  United States
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New Celestion "AxiPeriodic Driver"
thanks NC535, Flaesh,

Quote:
Originally Posted by Zero D View Post
What interests me, is celestion say it needs no Xover ! Of course it's not a piezo, so what's going on ?
That probably means no crossover is needed between the sections within that driver (a guess). The power handling small print mentions band limited noise, which I think means it still needs an overall highpass crossover to the driver in general.
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Old 23rd July 2016, 07:16 PM   #12
Patrick Bateman is offline Patrick Bateman  United States
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Originally Posted by nc535 View Post
AES New York 2015
Paper Session P6
Friday, October 30, 9:00 am — 12:30 pm (Room 1A08)
Paper Session: P6 - Transducers—Part 2: Loudspeakers
Chair:
Sean Olive, Harman International - Northridge, CA, USA

P6-6 Wideband Compression Driver Design. Part 2, Application to a High Power Compression Driver with a Novel Diaphragm Geometry—Mark Dodd, Celestion - Ipswich, Suffolk, UK
Performance limitations of high-power wide-bandwidth conventional and co-entrant compression drivers are briefly reviewed. An idealized co-entrant compression driver is modeled and acoustic performance limitations discussed. The beneficial effect of axisymmetry is illustrated using results from numerical models. Vibrational behavior of spherical-cap, conical, and bi-conical diaphragms are compared. Axiperiodic membrane geometries consisting of circular arrays of features are discussed. This discussion leads to the conclusion that, for a given feature size, annular axiperiodic diaphragms have vibrational properties mostly dependent on the width of the annulus rather than it's diameter. Numerically modeled and measured acoustic performance of a high-power wide-bandwidth compression driver using an annular axiperiodic membrane, with vibrational and acoustic modes optimized, is discussed.
That dude says he's from Kef in this video:

https://www.youtube.com/watch?v=F3wMIgoV2Y4

Kef is the corporate sibling of Celestion. So I'm guessing that this compression driver is either a new take on wide bandwidth transducers (possibly BMR-ish?) or else it's an application of some of the innovations from the KEF LS50 into Celestion's lineup.

If you do a search for "mark dodd coincident source array" you'll turn up some of his work on the LS50
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Old 23rd July 2016, 09:24 PM   #13
POOH is offline POOH  United States
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these might actually solve some issues we hornys have,, lol - nice
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Old 23rd July 2016, 09:40 PM   #14
Patrick Bateman is offline Patrick Bateman  United States
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Originally Posted by POOH View Post
these might actually solve some issues we hornys have,, lol - nice
I hate to be a cynic, but it mostly appears that Celestion noticed that BMS made some clever coaxial compression drivers, and due to the fact they're made in Germany, they're $1500 a pair.

I *love* Celestion, I use it in literally half my projects, but a large part of the reason they're so darned good is that they're ubiquitous. The reason that I can get a great Celestion compression driver for $50 is because that same compression driver is in powered loudspeakers that you can find on Amazon for $250. Basically economies of scale that smaller manufacturers like 18Sound and Faital don't have.

JBL could probably sell their compression drivers at similar price points, they're made in Mexico.
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Old 24th July 2016, 07:22 AM   #15
Juhazi is offline Juhazi  Finland
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Jbl's D2 dual diaphragm looks like another way to skin the cat. Anyway those are compomising at both ends of passband.
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Old 24th July 2016, 08:16 AM   #16
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by Patrick Bateman View Post
I hate to be a cynic, but it mostly appears that Celestion noticed that BMS made some clever coaxial compression drivers, and due to the fact they're made in Germany, they're $1500 a pair...
BMS is made in Bulgaria.
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Old 24th July 2016, 03:38 PM   #17
POOH is offline POOH  United States
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the diaphragm(s) and phase plug appear to be very proprietary.

i love the 1'" drivers from celestion and agree they sell them at really fair pricing. Never like the bms drivers in my system.
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Old 24th July 2016, 03:58 PM   #18
ErnieM is online now ErnieM  United States
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So basically it's a large diameter ring radiator with carefully optimized breakup modes to extend top octave response. Will be interesting to hear how it does compared to current alternatives.
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Old 26th July 2016, 08:00 PM   #19
Patrick Bateman is offline Patrick Bateman  United States
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Go figure, it looks like this *isn't* a clone of the BMS.

I read the press release, and took a cursory look at the driver, and assumed that it was *two* rings.

But it's not - there's one ring and one voice coil. So this *is* something new. Neat.

Click the image to open in full size.

I marked up their pic, to show what I mean. There are two acoustic pathways but only one voice coil and one diaphragm.

New Celestion "AxiPeriodic Driver"

In some ways this is the *opposite* of the JBL. The JBL has two diaphragms, two phase plugs, and one acoustic pathway. The reason that the JBL works is because everything is equidistant. This is key, as a pathlength difference of even half an inch would create comb filtering in the top octave.

If the Celestion only has one diaphragm, but has two pathways, than that would seem to indicate that they've designed the diaphragm so that the highs are coming off one portion of the diaphragm, while the lows are coming off the other. Perhaps by using BEM they were able to optimize the diaphragm to do this. (Similar to how small full range drivers work, but it's not a cone it's a ring.)
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Old 26th July 2016, 08:18 PM   #20
nc535 is offline nc535
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There is only one pathway but it's through a multiple aperture phase plug.
, which does have multiple paths thru it. The magic is the two layer, upper and lower, diaphragm with stiffening ribs that is able to be pistonic over the entire range.
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