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Thread: Dave, any interest in beryllium woofers?

  1. #1
    Join Date
    Dec 2005
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    Default Dave, any interest in beryllium woofers?

    I think alot of companies stay away from metal midrange drivers to avoid dealing with nasty resonances in the 4-6KHz range, but it looks like Paradigm is now sourcing 7" Beryllium midrange drivers from Brush Wellman for their Persona speakers.

    Not sure if OEM drivers will be available or only the raw foil (interestingly truextents website says they do beryllium ribbons as well) but would Ascend have any possible interest in making a speaker with a beryllium mid? A 7" beryllium driver seems to provide possibilities for all kinds of bookshelf or tower speakers.

    Also it seems to me beryllium, with an insanely fast driver (12,830m/s) with 2.5x the speed of sound of titanium (5080m/s) or aluminum (5,020m/s) should be able to keep up with leading edges of notes of a RAAL tweeter much better than any mid-woofer on the market other than possibly the Raidho diamond cone.

    Found some interesting images online of how a 4" beryllium driver performs visually in terms of maintaining shape and coherence while playing back audio.



    Last edited by Asliang; 06-22-2017 at 11:00 PM.

  2. #2
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    Default Re: Dave, any interest in beryllium woofers?

    Quote Originally Posted by Asliang View Post
    I think alot of companies stay away from metal midrange drivers to avoid dealing with nasty resonances in the 4-6KHz range, but it looks like Paradigm is now sourcing 7" Beryllium midrange drivers from Brush Wellman for their Persona speakers.

    Not sure if OEM drivers will be available or only the raw foil (interestingly truextents website says they do beryllium ribbons as well) but would Ascend have any possible interest in making a speaker with a beryllium mid? A 7" beryllium driver seems to provide possibilities for all kinds of bookshelf or tower speakers.

    Also it seems to me beryllium, with an insanely fast driver (12,830m/s) with 2.5x the speed of sound of titanium (5080m/s) or aluminum (5,020m/s) should be able to keep up with leading edges of notes of a RAAL tweeter much better than any mid-woofer on the market other than possibly the Raidho diamond cone.

    Found some interesting images online of how a 4" beryllium driver performs visually in terms of maintaining shape and coherence while playing back audio.

    I was experimenting / evaluating Be (and also AlBe) well before all of the hype of Beryllium drivers. They definitely offer some advantages over the more traditional cone / dome materials (I had been in discussion with Brush Wellman around 15 years ago). However, I found that many of these advantages were only with vapor deposited Be rather than pure Be film. I don't believe it is possible to offer a large enough diameter vapor deposited cone to function well as a midrange, as such - pure Be film or foil had to be used. Although I do recall Andrew Jones telling me that the midrange driver in the TAD Reference 1 was vapor deposited (and that was a 6.5")

    The cost increase to use the film was huge and I came to the conclusion (rather quickly) - that the massive cost increase really wasn't worth the rather small audible performance increase.

    This new line from Paradigm looks interesting - but I am rather confused as to the choice of a 7" midrange, this would require crossing that Be dome tweeter quite low to avoid woofer beaming issues, and Be domes should not be crossed too low...

    Additionally, Brush Wellman does not make drivers, they only produce the Be cone itself. Still, I would be curious as to how these woofers actually perform. Thanks for posting this!
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  3. #3
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    Default Re: Dave, any interest in beryllium woofers?

    I believe vapor deposited Be is supposed to be around 15um thick, and beryllium foil used to be in the 50um range, but current generation truextent Be foil is now down to 25um thick (the ones used in the Focal Utopia headphones) and so the difference between Be foil and vapor deposition is narrowing.

    As far as pairing a 7" with a 1" driver and the narrowing in dispersion, I think that might explain the deployment of the flowery looking waveguide that covers the entirety of both drivers.

  4. #4
    Join Date
    Dec 2013
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    Default Re: Dave, any interest in beryllium woofers?

    Since midrange drivers are usually crossed over around 2-3khz, it seems those problems at higher frequencies, especially above 10khz, would not be much of an issue.

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