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Old 29th December 2007, 10:09 PM   #1
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Default Transmission Line drivers

Ok, after researching enclosure benefits, I think I will definately
go with a TL sub to supplement my Acoustat 2+2's which already
have some fairly decent bass. I have several (8) KEF B139 SP1044
drivers that I've considered but they are definately older design
compared to todays woofers (see: Multiple KEF B139s).

I also have several (4) of the
carbon fiber woofers used in the Pioneer HPM-100's with the
treated cloth surrounds. Some (4) Realistic Mach One Woofers
and finally some (2) JBL 2242HPL's.
Has anybody any experience with any of thes drivers using
them in as larger of numbers of each particular driver for TL
enclosures? I am wondering which of the drivers would work
best in TL enclosure to go with the Acoustats?
Is there any criteria used to determine whether a particular
driver will work good in TL? Are drivers intended for sealed
or ported reflex enclosures usually best?
I plan on going with a fairly long line (10-16? ft.) to really
go deep!
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Old 29th December 2007, 11:09 PM   #2
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Hold fire on the Kef TLs. I'm building something interesting at the moment:

http://www.diyaudio.com/forums/showt...07#post1383707

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Old 30th December 2007, 01:53 AM   #3
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FYI: http://www.diyaudio.com/forums/showt...94#post1386594
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Old 30th December 2007, 05:27 PM   #4
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Default just some suggestions...

I believe that Calvin gave a design for a pair of 18 inch Beyma drivers in an ultra tiny Ripole design perfect mate for an Acoustat. Also if you have a standard 8 foot ceiling you should try bracing your 2+2's to the ceiling with a couple of turnbulkles and a small wooden plate (to protect your ceiling). You wedge the turnbuckles between the top of the speakers and the wooden plate at the ceiling. Make it tight and your bass will increase big time. You might also consider a hardwood brace a foot long on the inside of your Acoustat frames in the middle of each vertical side piece. This is where the four panels meet in the frame. Reason? Well I have seen ceiling braced Acoustat 2+2 frames crack in half due to the increased bass energy and since the top of the speaker is effectively clamped the only place the frame can bend is in the middle. I did not believe this could happen untill I saw a pair that had done so.
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Old 10th January 2008, 11:25 PM   #5
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I definately want to stick with any of the drivers listed above.
Want to use those and not throw out more $ for anything else.
I think I also want to stick with a TL rather than experimenting
with horns.
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Old 11th January 2008, 05:00 AM   #6
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We used to use a pair of single B139 TLs with acoustats... they work fine. With 4 per side you will have a BIG box, but it should sound awesome.

Lengthening the line will not give you more bass, it will actually produce less bass.

Scottmoose & i worked up an optimum TL for the B139 using MJK for all those still fortunate enuff to have some around. I have CADed up lines for single and double woofer lines, i could do 1 for 4 or you could build 2 double lines. The other possibility if this is too big would be to use 4 per side in a push-push, push-pull TL. With the flat face and skeletal basket the B139 would be ideal for this. That would allow you to put 4 in the same size box as 1, and get the swept volume of a pair with a maximum amount of isolation from time smear back thru rhe cone as well as a reduction in 2nd order distortion (given it is an older woofer this might well be the biggest bonus)

Here is a straight version... it could be folded into a rectangular box.

Click the image to open in full size.

http://www.t-linespeakers.org/projects/vProjects.html

dave
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File Type: gif b139-pushpushpushpull.gif (10.5 KB, 976 views)
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Old 12th January 2008, 07:07 AM   #7
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Quote:
Originally posted by coloradosound
I definately want to stick with any of the drivers listed above.
OK, with no specs except for the KEFs, can't help you beyond what Dave's already offered.

GM
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Old 13th January 2008, 07:59 PM   #8
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data on the 2242H(PL)'s are at:
http://www.jblpro.com/pages/pub/components/2242.pdf
and also more stuff at:
http://www.jblproservice.com/pdf/Dis.../2242H-HPL.pdf
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Old 13th January 2008, 08:16 PM   #9
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Hmm, it's my understanding that like Altec, the HP series has a different set of specs Vs the lower power rated units, so are you sure the 'H' specs apply to the 'HPL'?

GM
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Old 14th January 2008, 10:35 PM   #10
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GM,
I don't remember where I saw it, but I recall reading
somewhere that the only difference between the 2242H
and 2242HPL had something to do with a cover over the
magnet or something like that. I'll look around and try to
find that again. As far as the Rat Shack woofers and the
Pioneers I have nothing and would have to come up with
some measurement stuff. The only thing I know about the
Realistic Mach One's is that they were sealed design and
the Pioneer HPM100's were a bass reflex.
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