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Anyone interested in Bozhen tweeters?

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Comments

  • Thanks so much for organising!

    Hope these arrive soon and we can share measurements, ideas and listening impressions on this tweeter.

  • Boy oh boy, suddenly I am drooling over Purifi woofers and wondered if anyone has the crossover schematic from Rick Craig's Purezza design. I'm sure he wouldn't mind.

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • @tktran said:
    Thanks so much for organising!

    Hope these arrive soon and we can share measurements, ideas and listening impressions on this tweeter.

    I received the tracking # today, although they haven't actually departed yet. Manufacturer said DHL Express is 7-9 days. I will definitely measure mine and share the results, but it will likely be after MWAF August 5th. I doubt if I will have listening impressions for quite a while though.

  • @rjj45 said:
    Boy oh boy, suddenly I am drooling over Purifi woofers and wondered if anyone has the crossover schematic from Rick Craig's Purezza design. I'm sure he wouldn't mind.

    Yeah, that would be nice, they get really good reviews. But I'm skeptical you'll find the xo (1) If someone has the finished speaker does it even come with a xo schematic and (2) if someone has them do they frequent DIY forums.

    rjj45
  • I will have access to a pair of Purifi 7" if you want me to attempt that...

    rjj45
  • @Wolf said:
    I will have access to a pair of Purifi 7" if you want me to attempt that...

    Oh you tease! But actually dreaming of a 3 way with a 4.5 inch Purifi mid.
    But PM me if you want to let them go,

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • edited June 2022

    I have a pre-order for 8" PTT8.0X04-NAB-02, and PTT5.25X04-NFA-01 Purifi woofers.

    A little birdie told me a 4" mid is NOT in development, a little to my dismay.

    What IS being developed is a tweeter- apparently it is a high priority, as are paper or aluminium variants of all the current sizes.

    A different sized midrange eg. ?5" ?5.25" MAY be in the pipeline...

  • @rjj45 said:
    But PM me if you want to let them go,

    They aren't mine to let go, and I don't think the owner will.

  • Madisound looks to have the Purifi 4.5" mid-woofer in stock. That's what I was referring to.
    https://madisoundspeakerstore.com/approx-5-woofers/purifi-audio-ptt4.0x04-nfc-01-4.5-mid-woofer-4-ohm/

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • @Wolf said:

    @rjj45 said:
    But PM me if you want to let them go,

    They aren't mine to let go, and I don't think the owner will.

    ok. I understand.

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • edited June 2022

    @rjj45 said:
    Madisound looks to have the Purifi 4.5" mid-woofer in stock. That's what I was referring to.
    https://madisoundspeakerstore.com/approx-5-woofers/purifi-audio-ptt4.0x04-nfc-01-4.5-mid-woofer-4-ohm/

    Yes I was hoping for a pure midrange version in that size.

    But it’s not coming in that size.

    Perhaps the 5.25”. ;)

    I’m working on a family of Purifi speakers, which includes quad 8” alu (series parallel) 3 way with a pure midrange.

    A dual 8” variant might be a possibility; a lot depends on release date/supply constraints of the fibre cone 8” varietal (90dB/2.83V; 8 ohm nominal)

    So far constraints mean I’ve only got a 6.5” two way like everyone else:

    kenrhodesSteve_Leerjj45
  • edited June 2022

    Deleted (duplicate post)

  • @tktran said:
    So far constraints mean I’ve only got a 6.5” two way like everyone else:

    LOL.

  • @tktran said:

    @rjj45 said:
    Madisound looks to have the Purifi 4.5" mid-woofer in stock. That's what I was referring to.
    https://madisoundspeakerstore.com/approx-5-woofers/purifi-audio-ptt4.0x04-nfc-01-4.5-mid-woofer-4-ohm/

    Yes I was hoping for a pure midrange version in that size.

    But it’s not coming in that size.

    Perhaps the 5.25”. ;)

    I’m working on a family of Purifi speakers, which includes quad 8” alu (series parallel) 3 way with a pure midrange.

    A dual 8” variant might be a possibility; a lot depends on release date/supply constraints of the fibre cone 8” varietal (90dB/2.83V; 8 ohm nominal)

    So far constraints mean I’ve only got a 6.5” two way like everyone else:

    I will bring a 6 pack and come over tomorrow. Those look like they mean business!!

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • Heck of a drive and boat or plane ride there, Don. Thanh is in Oz.

    rjj45
  • @Wolf said:
    Heck of a drive and boat or plane ride there, Don. Thanh is in Oz.

    Yeah, my dry sense of humor again. Should have included a smily :)

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • Ran an impedance on each of them. Had to stop T/S sweep for inability to finish parameters because of the unconventional curve shape. The most I could get is Fs. The other thing I found odd is the treble Zmin at about 10kHz, as it gets pretty darn low. Not that added resistance is untoward or not an option, as padding is almost certain. It just may take different methods to keep the impedance in check.


  • When running sweeps of the BZ tweeter, does it need a cap like a real ribbon?

  • @Wolf said:
    Dcr is very low, so yes.

    Thanks for the heads up. I'll be sure to insert a series cap before FR sweeping my pair. So far, I have only done low power VC checks with an ohm meter and a low power DATS V2 impedance sweep.

  • If anyone is interested, here is the DATS V2 impedance curves for my pair. Very similar to Wolf's measurements. I did not have to stop the sweep like Wolf did. My DCR is just a little bit higher. I get the same Zmin drooping at about 10kHz. Fs on both tweeters is about 100Hz lower than Wolfs pair. I removed the thin plastic cover on the faceplate before testing, then put the cover back on when done. This thin cover was just to protect the fragile elements inside. If you measure them with the covers on, the extra air load affects the sweep just a tad (memories 1 & 2, not shown). I plan to bring these tweeters to Indy as part of my non-theme demo. A 2.5 way crossed at about 1.5kHz. To protect the fragile elements during transport, should I tape a small piece of cardboard over the faceplates? I have seen others do this when transporting ribbon tweeters. Thanks.

    tktran
  • I would.

  • There is no need to protect the Bozhens like that of RAAL or AC units, except to prevent dirt from falling in through the grills. On Bozhen's website, they show a weight sitting on the membrane. They are thicker than you think. You can't do that with true ribbons, AMTs, or planars. The Bozhen is a different beast of a tweeter, and truly a "new type" as they call it.

  • How low can these go? Bill is there something you are basing the 1.5k XO on?

  • @ani_101 said:
    How low can these go? Bill is there something you are basing the 1.5k XO on?

    The manufacturers' website says that this tweeter can reliably be crossed as low as 1kHz:
    http://bzspeakers.com/ribbon76b_en.html?v=20220811
    I have no basis for a 1.5kHz xover. This is just a starting point. After mounting the tweeter and running up a full set of measurements, I'll test a variety of xover points in VituixCAD to see how it blends with my woofers (esoteric 7"). I'll push it as low as I can based on phase tracking, on-axis FR, in-room power response, and distortion testing.

    ani_101rjj45
  • @4thtry said:

    @ani_101 said:
    How low can these go? Bill is there something you are basing the 1.5k XO on?

    The manufacturers' website says that this tweeter can reliably be crossed as low as 1kHz:
    http://bzspeakers.com/ribbon76b_en.html?v=20220811
    I have no basis for a 1.5kHz xover. This is just a starting point. After mounting the tweeter and running up a full set of measurements, I'll test a variety of xover points in VituixCAD to see how it blends with my woofers (esoteric 7"). I'll push it as low as I can based on phase tracking, on-axis FR, in-room power response, and distortion testing.

    Thanks Bill, looking forward to your tests and how low the tweeter can handle normal listening volume.

  • CQ76 was tested by AudioXpress:
    https://audioxpress.com/article/Test-Bench-Bozhen-CQ76-Ribbon-Tweeter

    Shows no sign of stress down to 1kHz at 94dB/1m.

    rjj45
    I'm not deaf, I'm just not listening.
  • That is not the B version we are referring to here, but still valid for performance.

  • I assume this is the "B" version, then, but only tested to 2kHz here because Vance is inconsistent AF.
    https://audioxpress.com/article/test-bench-an-updated-cq76-ribbon-tweeter-from-bozhen-new-audio-lab

    I'm not deaf, I'm just not listening.
  • @Wolf said:
    Dcr is very low, so yes.

    What size cap would you suggest?

    dcibel
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