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JBL 2242's coming soon!!! [message #46455] Mon, 07 March 2005 12:57 Go to next message
spkrman57
Messages: 522
Registered: May 2009
Illuminati (1st Degree)
Wayne,
Broke down and bought a pair of JBL 2242H 18" drivers. JBL intended these for sub-woofer duty for theaters. (For those who don't know how much they cost, they list for $839.00 each. You could buy a used car for that kind of money!!!

Anyways, I am looking forward to using them in 9 cubic ft cabs with dual 6" ports tuned to 30hz. They are 99db/watt and are great for sub duty bandwidth limited to 80hz on the top end. Bottom end is 3 db down at 35hz.

I will have to get the specs and have you see what "Pi-alignment" would come up with!!!

Regards, Ron

Re: JBL 2242's coming soon!!! [message #46456 is a reply to message #46455] Mon, 07 March 2005 14:01 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18791
Registered: January 2001
Illuminati (33rd Degree)

Those are excellent! For subwoofer use, I like them in 8-10ft3 tuned to 30Hz, which is PiAligned for a 2245 and EBS for a 2241 or 2242.


JBL 2242 in Pi alignment cabinet [message #46458 is a reply to message #46456] Mon, 07 March 2005 14:55 Go to previous messageGo to next message
spkrman57
Messages: 522
Registered: May 2009
Illuminati (1st Degree)
Wayne,
I think you have the T/S parameters for that driver, what does Pi alignment come up with, and what would the -3db be at.

Down the road, I might want to downsize these cabinets and want to see how bottom end would be lost in a smaller cabinet.

Here is link to JBL 2242 driver specs if you don't have them:

http://www.jblpro.com/pages/pub/components/2242.pdf

Thanks, Ron

Re: JBL 2242 in Pi alignment cabinet [message #46460 is a reply to message #46458] Mon, 07 March 2005 17:19 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18791
Registered: January 2001
Illuminati (33rd Degree)
There's a PID datafile in PiAlign for the JBL2242 called JBL2242.pid. You can load it up pressing the [ESC][TAB][TAB] keys in that order, and then type "JBL2242." A PiAligned cabinet for the 2242 is 2.5ft3 and tuned to 50Hz with a 4.25" x 7.5" rectangular port that's 7.0" long. That's a great size for the woofer of a nice little three-way system or something like that. The response curve is flat, although not that deep. Both the JBL 2241 and the 2242 are tuned this way, optimized for maximum output at the expense of extension. The f3 point is 60Hz and f10 is 45Hz.

Re: JBL 2242 in Pi alignment cabinet [message #46468 is a reply to message #46460] Tue, 08 March 2005 06:13 Go to previous messageGo to next message
spkrman57
Messages: 522
Registered: May 2009
Illuminati (1st Degree)
Thanks for the info Wayne. It is interesting to see the EBS alignment takes the driver almost a octave lower.

I will report back how the drivers sound when they come in this week or next. Hard part will be breaking them in since my sub plate amps are only 185 watts each @ 8 ohms. It might take a month or 2 with a 800 watt driver. But it will be nice when that happens.

Now I will have a adequate sub for my Edgarhorns.

One more question, what would the 7 Pi - 18" enclosure do for this driver, and how large would it be????

I don't know if the bottom end response would be any better than the 9 cubic ft ported to 30hz enclosures that I have now, but looking at all possiblities. If I ever went that route, Bill Epstein would be mighty busy building them for me!

Ron

You've got mail! [message #46470 is a reply to message #46468] Tue, 08 March 2005 06:38 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18791
Registered: January 2001
Illuminati (33rd Degree)

The EBS alignment gets its name extended bass shelf from the type of response curve it gives. Response falls off up in the midbass or midrange and stays at this reduced shelf down to another point where it rolls off rapidly. So what you gain in extension, you lose in sensitivity. Nothing comes free.

As for your question about the seven π cabinet, I've sent plans so you can take a look for yourself. What you'll gain is 9dB DI and no response anomalies or bottom end rolloff that requires EQ to make it right. Just run it flat, and you can use a nice tube amp if you want. You'll also get a uniform reverberent field, because the directivity of each of the horns is matched at 90°. The sound produced has a very lifelike 3D quality, and it isn't confined to one "sweet spot" but is uniform over a large area of the room. I guess you could say the sweet spot is very large.

This is important for reasons other than a wide listening zone. Sound that is reflected back at you from the walls and objects in the room has the same tonal balance as direct sound does, and it is much more natural than a speaker that doesn't have this quality. When listening to other speakers, if you can walk around the room and the sound changes from location to location, then the room isn't very uniform and sounds reflected back are unnatural, even when listening in the "sweet spot."

Some people try to treat the room to make it as dead as possible, but this is fighting a losing battle. You can fix room problems with room treatments, but you can't fix speaker problems with room treatments. Better to fix the speaker instead. With the seven π loudspeaker, what you get is good response on-axis as well as off-axis, and uniform sound throughout the room.


Thanks Wayne! [message #46472 is a reply to message #46470] Tue, 08 March 2005 10:47 Go to previous message
spkrman57
Messages: 522
Registered: May 2009
Illuminati (1st Degree)
I will have to check out the plans when I get home as I try not to send anything to work here(they are coming down harder nowdays).

Ron

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