Need Advice - Big Motor 15" Coaxial - diyAudio
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Old 12th December 2007, 01:19 AM   #1
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Default Need Advice - Big Motor 15" Coaxial

What cabinet design would you recommend for the PAS CXL-2580C - It's a beast of a driver. The biggest motor single driver I have ever seen.

Click the image to open in full size.

Surely I could put it in a bass reflex, but I'm looking for a design that will take better care of the back wave to reinforce the bass. Size is an issue, I really don't want to go over 24" wide but it can be tall and deep. I don't want to use baffle step correction, I'd rather build the right cabinet to use the back wave energy. I have had BIG back loaded horns and find the delay off the back side mating with the radiation off the front presents problems mucking up the upper bass. This is unacceptable to me. I want the bass to be tight, strong and linear.

What do you think about a tuned quarter wave pipe for a driver like this? Compared to a back horn? What is the least compromise? Why? What other cabinet will be the best compromise?

The cabinet will be 6' from the front wall so it will be pretty much on it's own. What do you do about floor bounce reflections with single drivers? Don't you get a horrific dip?

They only need to go down to 50 cycles strong, I have an appropriate sub. If the bottom end gets too strong, I have a front horn for the 15 to even it out.

It seems you guys are good at getting the best ot of the little 8" 'full range' drivers, so please advise what you'd do with this.

Thanks
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Old 12th December 2007, 01:23 AM   #2
flshzug is offline flshzug  Antarctica
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0this is the 2" HF driver version of the coaxial used in UREI 811B - 813B -815B. I did simulations on their low end response , and guess what bought some JBL 15 inchers since.
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Old 12th December 2007, 01:24 AM   #3
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Quote:
Originally posted by flshzug
0this is the 2" HF driver version of the coaxial used in UREI 811B - 813B -815B.
Yes, I don't want to add 15's like UREI - this also has a bigger, stronger magnet and 4" voice coil
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Old 12th December 2007, 01:38 AM   #4
flshzug is offline flshzug  Antarctica
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these cxl-s were sold on ebay some time ago and i gave it a tought , but even If I skip JBL's for the coaxials, they most likely would be the neodymium Beyma 15" or 12"s . I bought the JBL's 'cause I can forget about seperate subwoofers ( think of 4435 hehe ) now.
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Old 12th December 2007, 01:45 AM   #5
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Quote:
Originally posted by flshzug
these cxl-s were sold on ebay some time ago and i gave it a tought , but even If I skip JBL's for the coaxials, they most likely would be the neodymium Beyma 15" or 12"s . I bought the JBL's 'cause I can forget about seperate subwoofers ( think of 4435 hehe ) now.

I have the top of the line Beyma DX15 - with 4.5" coil and large format compression driver. They are very good, these seem to be better in the midbass and mid in my test box though. Also like the bigger horn and choice of compression driver.

I got these off ebay for 129 a pair! LOL - they are MINTY
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Old 12th December 2007, 01:46 AM   #6
CLS is offline CLS  Taiwan
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I notice it has a relatively small Vas for such a big driver, so BIB comes to mind

(Or I should say, BBBIB ? )

Just plug the numbers in, I got:

Vb = 460.3 L
H = 207.3 cm
W = 39.6 cm
D = 56.0 cm
Height of Driver = 114.4 cm


Looking good
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Old 12th December 2007, 01:52 AM   #7
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Quote:
Originally posted by CLS
I notice it has a relatively small Vas for such a big driver, so BIB comes to mind

(Or I should say, BBBIB ? )

Just plug the numbers in, I got:

Vb = 460.3 L
H = 207.3 cm
W = 39.6 cm
D = 56.0 cm
Height of Driver = 114.4 cm


Looking good
Sorry - I'm not up on that lingo yet! What is this BIB and how did you already derive the numbers?!?

the size seems fine but why the high driver ???
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Old 12th December 2007, 02:20 AM   #8
CLS is offline CLS  Taiwan
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BIB is a long story.

To make it short, here is the basic configuration:
http://www.zillaspeak.com/bib-howtobuild.asp


And here is all the calculations come from:
http://www.diyaudio.com/forums/showt...33#post1190733


And here is the built BBBIB:
http://www.diyaudio.com/forums/showt...hreadid=106083


That is 12incher version, now you can make a 15incher one

Almost all BIB related thread are very long. It's hard to keep following.

Actually I never build any of them, just keep planning. Too many projects, too little time ....
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Old 12th December 2007, 02:23 AM   #9
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By height of driver, he means center of driver above floor level.
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Old 12th December 2007, 02:39 AM   #10
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I see, still too tall, three feet would be ideal for me at center. - I found the BIB website from Godzilla - These look like they may have some bass ripple? I'm reading about this...... hmmm - it's almost a horn - why not add a back chamber?

Click the image to open in full size.
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