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In Reply to: RE: Some sealed vs vented ramblings posted by Duke on December 22, 2009 at 21:51:29
While I prefer a big sealed box (something like 30 square foot is close enough to being infinite for smaller drivers) it is not a black or white choice.
A normal size bassreflex system can i.e. be tuned to 35-41 Hertz and thereby reduce the cone movement a lot. This will reduce distortion compared to a same size sealed box.
Secondly the port does give a more open sound in many systems.
I normally design loudspeakers including a foam plug, so that the owner can convert the bass reflex box to a sealed box.
Converting a sealed box to a bass reflex would require drilling holes by the owner:-)
Merry Christmas !
Follow Ups:
I assume you choose the volume of the box so when sealed the Qtc is a tight one and the F3 is reasonably low. Just closing a port may not work.
I was fortunate. The designer of my woofers took all these factors into account. I ended up with the closed format because of superior control. But I ended up with an F3 of 33 Hz rather than 23 Hz which isn't too important except for deep organ notes and low frequency room affects(if they're on the software) and a few other times.
Thanks, Ole!
I like your idea of being able to convert the box from ported to sealed, that makes the speaker usable out in the room or up against the wall.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Nobody has mentioned the Nestorovic woofer system. It's not as well known as it should be.
If you are unfamiliar, it's a hybrid of the sealed and vented designs using two electrically overdamped/mechanically underdamped woofers, typically one larger thatn the other (i.e.: one 10-inch, one 12-inch). The system operates in a sealed enclosure with both woofers operating essentially in parralel, down to a point where the larger woofer is attenuated (between 50-100Hz) so it begins to act like a passive radiator. It won a patent in th late '70's, I believe it's expired.
Great system. Some of Nestorivic Labs' speakers were very well regarded and even won some A and B Stereophile ratings (don't recall which models got specific ratings). I personally own a pair of Model 3's, very similar to the Speakerlab S30 (a late 70's kit speaker), and you would not believe the depth and control that this 1.7 cubic ft enclosure is capable of.
Paul Johnston "The LoudSpeaker Guy"
Owner and Chief Loudspeaker Biologist
Kent, WA USA
www.theloudspeakerstore.com
My uniform experience over 50 years with sealed box speakers is that they have two unacceptable characteristics: They sound muffled-very little if and only if they are expensive(near and above $5k) and they lose a good bit of the music as they are turned down.At low levels they've lost a lot.
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