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Old 23rd January 2014, 09:23 PM   #1
tca is offline tca  Portugal
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Default Bradford Perfect Baffle

Did anyone tried this?

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Here is the patent: https://www.google.com/patents/US2834423
and some more info: retro vintage modern hi-fi: Bradford Perfect Baffle

Cheers.
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Old 7th February 2014, 10:04 PM   #2
tca is offline tca  Portugal
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I guess it is just a form of an aperiodic enclosure... a leaky box.

P.S. (edit)
Two more refs.:

- https://www.google.com/patents/US7481295
- https://www.google.com/patents/US3233695
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Last edited by tca; 7th February 2014 at 10:33 PM.
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Old 9th February 2014, 09:03 PM   #3
freddi is offline freddi  United States
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Merle Haggard - Swingin' Doors (with lyrics) - YouTube

- -"According to my invention, I provide in at least one wall of a totally enclosed cabinet, or bafiie, what might be termed a pressure relief valve one example of which is the formation of an opening or passage in said cabinet communicating with air therein, and supporting within this opening with suitable clearance between its perimeter and the edges of the opening, a freely swingable door. This door should be very light so as to have a minimum of inertia and it is preferably suspended within said opening with non-metallic means."
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Old 9th February 2014, 09:48 PM   #4
tca is offline tca  Portugal
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Quote:
Originally Posted by freddi View Post
Merle Haggard - Swingin' Doors (with lyrics) - YouTube

- -"According to my invention, I provide in at least one wall of a totally enclosed cabinet, or bafiie, what might be termed a pressure relief valve one example of which is the formation of an opening or passage in said cabinet communicating with air therein, and supporting within this opening with suitable clearance between its perimeter and the edges of the opening, a freely swingable door. This door should be very light so as to have a minimum of inertia and it is preferably suspended within said opening with non-metallic means."
Yes, I know... did anyone try to build one?
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Old 10th February 2014, 02:42 AM   #5
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Quote:
Originally Posted by tca View Post
Yes, I know... did anyone try to build one?
Sounded like a Kazoo
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Old 10th February 2014, 11:30 AM   #6
DrBoar is offline DrBoar  Sweden
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If the leaking around the flapping part is small the thing is a bass reflex with a passive radiator with a far higher tuning frequency than normal. Otherwise is some kind of amplitude modulated resistive vent.

DIY
go to a fleamarket and buy the cheapest pair of closed boxed you can get.
Cut a large hole on one box
Cut a piece of cardboard slightly smaller than the hole
Suspend the cardboard in the hole.
Play some music and se the cardboard flap around....
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Old 10th February 2014, 11:32 AM   #7
xrk971 is offline xrk971  United States
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Maybe it should be called a "Flapping Baffle" (FB)?
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Old 11th February 2014, 04:15 AM   #8
freddi is offline freddi  United States
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fwiw - for cabinets of that era, I like the R-J

Click the image to open in full size.
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EV SP15 in the 15" RJ
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Lafayette's "Eliptoflex"
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one of my 4 old 18" RJ vent path woofers
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Old 11th February 2014, 04:29 AM   #9
freddi is offline freddi  United States
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here are two papers concerning the R-J

http://downloads.bbc.co.uk/rd/pubs/reports/1955-08.pdf
http://www.jumpjet.info/Pioneering-W...CA/1952-04.pdf
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Old 11th February 2014, 04:40 PM   #10
DrBoar is offline DrBoar  Sweden
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There was a swedish company that made similar bass reflex boxes. That is a subbaffle that creates a roughly conical cross section of the vent. Perhaps was the idea that a cicular vent close to the cone would confer some symetric loading? Jamo in Denmark had two concentric tubes outside with the driver in the center. The gap between the tubes formed a vent with a straight cross section around the driver.
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