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-   -   Would you consider this an OB? (http://www.diyaudio.com/forums/full-range/198982-would-you-consider-ob.html)

talaerts 21st October 2011 11:49 AM

Would you consider this an OB?
 
All, at 6 Moons they cover a speaker that interested me as it uses 4 FR drivers and a ribbon tweeter:

6moons audio reviews: J.A.F. Bombard

http://www.6moons.com/audioreviews/jaf/1.png

The thing is, it is marketed as an innovative kind of open baffle.
Now, considering that there are 4 drivers, and a narrow open slit at the back, wouldn't it behave more like a bass reflex box?

tinitus 21st October 2011 11:58 AM

Quote:

Originally Posted by talaerts (Post 2753528)
The thing is, it is marketed as an innovative kind of open baffle.
--------wouldn't it behave more like a bass reflex box?

neither

Godzilla 21st October 2011 01:12 PM

I wonder how the slot contributes to the overall sound? At first i thought it would be interesting if the speaker opened and closed at the back to adjust the 'wings.'

norman bates 21st October 2011 01:14 PM

I see it as an ob. That design would not have a double spiked Z-plot similar to a ported box.

I may have another future project.

Norman

Cal Weldon 21st October 2011 01:51 PM

It's a back loaded horn that uses a corner to complete the flare. :)

Godzilla 21st October 2011 05:00 PM

>>> It's a back loaded horn that uses a corner to complete the flare.

Like a BVR.

I hear ya Norman... i think it's a cool idea too.

norman bates 21st October 2011 11:13 PM

8" drivers don't have squat dispersion, so multiples (vertically) shouldn't interfere with each other. The hemptone climbs past 1khz (from posts I've seen), so that should help off axis not falling off too badly. And lastly the impedence of the tweet (and cap) stays low while the impedence of the fullrangers skyrocket as it goes higher, so the response of the fullrangers will be rolling (higher than if run wide open) off due to the energy flowing to the lower resistance load. And they use a coil to roll off some more from the woofs.

Seeing from earlier thread on "whizzers and intelligibility", I suppose we need the whizzer to help the off axis a bit past 2khz (for an 8" driver), but maybe use a flatish 8" but add a 3" phase plug ?

Neat neat idea. But how nicely does the hemptone do for 1-5khz ? That would be the question. People have liked them, but I'm not sure I want to drop $420 to find out. Maybe I'll run 4 x silver flute but add a phase plug. Then I'd need a stout tweet also (96db or so)

Norman

chrisb 22nd October 2011 12:39 AM

as wonderful as these may sound, and as "revolutionary" (my word) as this "proprietary folded version of the oldest 'patent' in loudspeaker construction" may be, it's pretty hard to think of it as an OB

rjbond3rd 22nd October 2011 01:56 AM

Viewed from above, it's a tapered (~10-to-1) TL with a line length of ~12" and no driver offset :)

GM blew my mind with this:

Quote:

Originally Posted by GM (Post 2191638)
Viewed another way, an OB is the inverse of a high gain TL, so as the long TL that only has the same pipe area as the driver's effective piston area (Sd) wants a strong motor (low Qts), the unfolded TL (OB) wants a proportionally weaker motor (higher Qts) and smaller baffle.

Link: http://www.diyaudio.com/forums/full-...ml#post2191638

GM 22nd October 2011 03:05 AM

Quote:

Originally Posted by Cal Weldon (Post 2753643)
It's a back loaded horn that uses a corner to complete the flare. :)

Yeah, what was once old is yet new again. As a standalone, it's ~aperiodically loaded like the Fonken series.

GM


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