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AUDIO FORUMS >> D.I.Y. >> My absurd question of the day - radial ZOB
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Message started by chris_m on 02/06/10 at 01:54:49

Title: My absurd question of the day - radial ZOB
Post by chris_m on 02/06/10 at 01:54:49

I just finished building a full range speaker set using JX92's in MLTL cabinets.  I agree with Steve's comments about the benefits of the full range driver approach in terms of image and coherence. It's a very noticable improvement over my existing speakers even though the MLTL design retains the disadvantages that come with high cabinet pressure levels.

One of the things that amazes me about the ZOB design is how effectively the driver couples to the resonate cavity from one side.  But I certainly do believe the reported results.

A question popped into my head reading the four articles on the ZOB development .  What if the driver was turned to point vertically upwards, similar to a radial design and the gap that acoustically couples to the cavity beneath could be a continuously circular gap to a cylindrical cavity beneath it.  Some kind of inverted cone above the cone of the driver cone would have to redirect the sound horizontally.  But if this could be done I wonder if 1) more energy could couple to the cavity to achieve perhaps lower the 3dB cut off, and 2) could some imaging benefits of radial design furthe enhance the imaging?

In practice a six or eight sided cavity could approximate a cylindrical cavity.

So much for absurd ZOB notions.  I welcome any and all reactions.

Chris

Title: Re: My absurd question of the day - radial ZOB
Post by chris_m on 02/09/10 at 13:54:55

I guess this off the cuff blurt has only garnered some eye rolling or raised eyebrows.  Rightfully so given some of the asurdity of it.

The the idea has given way to another thought. Still placing a driver in an open baffle and coupling to a resonate chamber a la ZOB, but instead of a cubical chamber below the driver I'm thinking about a cylindrical chamber axilly placed behnd the driver and coupling to it over the full circumfrence of the driver.  If I can come up with an inexpensive driver to try it with I am thinking about an exeriment with sono tube for the chamber.  The port would be out the back end of the chamber.

Title: Re: My absurd question of the day - radial ZOB
Post by Chris K on 02/09/10 at 18:28:55

Try it!

Title: Re: My absurd question of the day - radial ZOB
Post by Yoda on 02/10/10 at 01:43:43

I was thinking of sometime making an double ZOB - one w/ a top and bottom chamber, single driver.  one of my first experiments was that I built 2 pair of back loaded horns for the fostex fe83 and inverted one on top of the other to make a two driver double horn - it was fantastic w/ piano!  Radial seems like it would be very interesting, whether it is horizontal or vertical...very intrigued

give it a shot!

Matt

Title: Re: My absurd question of the day - radial ZOB
Post by BLFST on 02/11/10 at 01:05:19

I'm more interested in your having an enlarger in the center of your listening setup (LOL).

Title: Re: My absurd question of the day - radial ZOB
Post by chris_m on 02/11/10 at 03:01:57

So that's what that is.  It looked familiar but I could place it.  Very interesting.

My thanks to the comments of encouragement for trying experiments based on the ZOB.  Since finishing my Jordan in MLTL I seem to need another project to occupy myself with.  I look forward to reporting back with some progess.

Chris

Title: Re: My absurd question of the day - radial ZOB
Post by Yoda on 02/12/10 at 03:28:17

Ah, The joys of living in a one bedroom apt and having photo and stereo gear.... That was an old picture, taken prior to any Decware acquisitions or builds.  Gear in that photo:  Thorens TD160, HK Cassette Deck, Golden Tube Audio SEP-SE pre w/ battery phono, Technics MASH CD,  Hafler DH-200, some Yamaha tuner...and a 1950's Omega D-2 enlarger for room treatment.  At the time, I was planning to mod the Hafler ala Musical Concepts or Van Alstine and buy some Maggies.  Then I heard some Cain and Cain Abbeys....leading to experiments w/ 3" Fostex full range speakers...and my first beloved SE-84C.




Title: Re: My absurd question of the day - radial ZOB
Post by chris_m on 02/12/10 at 15:03:58

Your idea of dual chambers on either side of the full range drive seems like a straight forward extrapolation of the XOB design.  It also shares some of the same theme as your fostex design.

If one could replace the cubical chambers with a round, sonatube like chamber it could reduce cost and simplify a prototype.  But I have no idea how to size it for the resonant frequency yet.  That's a first step for me I haven't figured out yet.

I see you are listening through HDT's now.  How does that render music compared to your fostex and other speakers you've tried?

Title: Re: My absurd question of the day - radial ZOB
Post by Yoda on 02/27/10 at 02:43:26

I had a hard time tuning those horns and finding the correct internal damping that would cut mid-range transmission through the horn - honking - without killing the bass.  What those horns did well was sound very open and 'live' w/ piano and cello and other resonant type instruments. There was more bass than you'd expect a 3" driver to produce, and I always thought that driver would work well open baffle w/ a bass horn.  I also tried small fostex/s in vented enclosures, but found that they sounded as if some of the soundstage was lost.   The HDT mk I's had a similar presence as the horns, but a much fuller and controlled sound.  I converted my HDT's to the mk II driver configuration and found it to be a very relaxed and balanced speaker.  I missed the fostex experience and had Steve modify my drivers 9 mos ago, and I intend to try the alternate tuning HDT any weekend soon...

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