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[regsaudioforum] Re: Diamond Tweeter!

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  • Tom Mallin
    I have no real evidence of what I called the voicing peak was intentionally added. I just meant that these lower-down peaks couldn t be the ultimate tweeter
    Message 1 of 46 , May 1, 2007
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      I have no real evidence of what I called the "voicing peak" was intentionally added.  I just meant that these lower-down peaks couldn't be the ultimate tweeter resonance since they are not big enough or have a high enough Q. 
      On the other hand, B&W could certainly get the response flatter than this if they wanted to, assuming the measurements accurately reflect the actual behavior of the speaker, and I trust JA's experience on that count.  Could this elevation be meant to add back a perception of detail sucked out and covered over by the Kevlar midrange yet further down?
      These B&W speakers don't sound obviously really bright.  Making the upper bass generous ("ripe" the review says) balances the overall tonal impression considerably, compared to what they would sound like without a generous mid to upper bass.  That is a type of "voicing," I'd say.

      >>> regonaudio@... 05/01/07 02:55PM >>>
      Thanks for posting this up. I had a look.
      I have not heard the speaaker, but the four-five dB peak at 10k and a
      little below worries me.

      With all due deference to GF, I do not see how this could sound
      Of course one could DSP it to flat. But four dB is a good bit.
      Try it for yourself if you want to: put a four dB peak at 7-10 k into
      your speaker.

      Incidentally, materials colorations are usuall;y felt to involve
      breakup patterns and response issues related thereto.
      I think it is true that the diamond tweeter is quite free of breakup
      to way high.

      I am curious about the "voicing peak" concept. Is it your belief(TM )
      that the 8-10k thing and the peak below were done on purpose?
      I would be glad to know.


      PS For what is is worth, the "natural" behvior of a pistonic radiator
      free of breakup in not flat--there is a rise in higher frequencies
      associated to the change in air loading followed eventually by a
      rolloff.  One has to do things to speakers to make them flat!

      --- In regsaudioforum@yahoogroups.com, Tom Mallin<tmallin@...> wrote:
      > Stereophile's test of the
      B&W 802D diamond tweeter model does show
      that the ultimate tweeter resonance is way above the audible range. 
      There are voicing peaks further down the spectrum, however, and the
      Kevlar midrange is still there to limit ultimate midrange clarity and
      > >>> uli.brueggemann@... 05/01/07 05:08AM >>>
      It must sound like carbon.
      > Or like expensive :)
      > BTW a
      speaker sound like its material only if the material is allow
      to play its own sound. Seriously: each material has its own
      frequencies off course. If these frequencies fall into the range of
      frequencies to be reproduced by the driver then some colouration will
      be added (non-linear distortions). If the frequencies are outside
      this range then it is a question how a crossover will suppress them.
      > So IMO the idea behind the diamond tweeter
      is to get very high cone
      resonance frequencies due to the high rigidity of the diamond.
      Outside of the working range of the tweeter.
      > On 5/1/07, eelekim1974 <eelekim@...>
      > Has anyone heard the new Avalon Eidolon (
      href="http://www.avalonacoustics.com/dia.html">http://www.avalonacoustics.com/dia.html ), the model more or less
      > originally designed for the Reference
      Recordings studio? I've never
      > imagined a speaker disphragm can be made
      of diamond!
      > We all know that speaker sounds like its material.
      For example,
      > cone sounds metallic. But diamond? :P
      > mike

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    • joel
      Boron is still quite widely used for cartridge cantilevers, but there are questions of cost and supply. AFAIK there are only a couple of cantilever assembly
      Message 46 of 46 , May 5, 2007
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        Boron is still quite widely used for cartridge cantilevers, but there are questions of cost
        and supply. AFAIK there are only a couple of cantilever assembly manufacturers left.
        Beryllium never really caught on because, as so vividly explained, it is difficult and
        dangerous to manipulate, but IIRC Yamaha is part of the Sumitomo Heavy Industy keiretsu
        (a much less significant fact no than it was 20 or 30 years ago) and is also a large
        manufacturer and designer of LSIs among amny other things, which provides access to a
        range of industrial processes and manufacturing skills most hifi companies can only
        dream about.

        > If by "such applications" you mean cartridges, I don't know about carbon
        > nanotubes, but Dynavector has had models with solid diamond cantilevers,
        > such as:
        > http://www.dynavector.com/products/cart/e_17d3.html
        > >>> rtuck@... 05/04/07 05:00PM >>>
        > The health and safety implications of dealing with beryllium and its
        > oxide
        > are very onerous. The key issue is to avoid inhaling or getting skin
        > penetration of any dust from working the material - causes berylliosis
        > http://www.emedicine.com/med/topic222.htm
        > When I worked on microwave tubes we used beryllia ceramicsReceived: from PLRBDOM-
        MTA by mail.plrb.org
        because they
        > had
        > a low dielectric constant and high thermal conductivity. The ceramics
        > came
        > packed with a plastic film over them, only removed at the last minute
        > the
        > nightmare was a dropped and broken ceramic. There were extensive
        > clean-up
        > procedures including a beryllium only vacuum cleaner with a HEPA filter
        > on
        > the outlet. We never faced the problem of a full bag in the machine
        > but I
        > guess we would have scrapped the whole machine via a licensed route.
        > As far as cartridges go I guess that constant handwork with small
        > parts,
        > even with gloves, exposed the workers to skin penetration and dust
        > inhalation.
        > Has anyone yet tried carbon nanotube composites for such applications?
        > Richard
        > -----Original Message-----
        > From: regsaudioforum@yahoogroups.com
        > [mailto:regsaudioforum@yahoogroups.com]
        > On Behalf Of regtas43
        > Sent: 03 May 2007 22:57
        > To: regsaudioforum@yahoogroups.com
        > Subject: [regsaudioforum] Re: Diamond Tweeter!
        > I think it is getting harder to do things with these toxic metals.
        > The Audio Technica ATML 170, which some people felt was an all time
        > good
        > cartridge, was discontinued because the boron cantilever's manfacture
        > became
        > outlawed in some way.
        > REG
        > Please remember to go to
        > http://www.theanimalrescuesite.com/clickToGive/home.faces?siteId=3
        > and click to help the rescued animals.--- In
        > regsaudioforum@yahoogroups.com,
        > "joel" <joel@> wrote:
        > >
        > > The tweeter is beryillium as well.
        > > The domes are created by a process of be vapor deposition onto a
        > (IIRC) pure copper mold
        > > which is then burnt off in an acid bath. Yamaha allegedly made
        > speakers that used forged
        > > beryllium for the mid and HF drivers back in the late 80s. However,
        > these were ridiculously
        > > expensive and large "statement" speakers. Quite possibly the real
        > vaporware :-)
        > > The "rainbow" effect of the be drivers is hypnotically beautiful in
        > the same way the bright
        > > patterns on highly venomous snakes are...
        > > Mitsubishi Electric's speaker brand in Japan is Diatone, under
        > whose banner MEE made the
        > > monitor speakers for NHK for several decades. Diatone also use a
        > vapor deposition
        > > process for the mid and HF units on their speakers, but use boron
        > in place of beryllium.
        > >
        > >
        > > Joel
        > >
        > > > The Yamaha NS1000 had a beryllium dome midrange.
        > > > Beryllium s a tricky material because the dust of it is very toxic
        > > > so manufacturing work has to be carefully controlled.
        > > >
        > > > REG
        > > >
        > > > --- In regsaudioforum@yahoogroups.com, "Tom Mallin" <tmallin@>
        > wrote:
        > > > >
        > > > > Beryllium was used in drivers before diamond, I think. JM
        > Focal is
        > > > one
        > > > > company which has used such drivers for awhile now.
        > > > >
        > > > > Also, in the 1970s Micro Acoustics marketed an unusual
        > cartridge one
        > > > of
        > > > > the features of which was a beryllium cantilever. I think the
        > model
        > > > > number of the one I had was 2002e. Not bad, but a tad bright
        > for my
        > > > > tastes, which ran more to the Shures and ADC XLM at that point
        > in
        > > > time.
        > > > >
        > > > >
        > > > > >>> will_hum@ 05/01/07 09:10PM >>>
        > > > > Diamond is so passé! Don't you know? The new "in" is
        > Beryllium!
        > > > >
        > > > > :)
        > > > >
        > > >
        > >
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