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P AUDIO - 15" DRIVER AND BAFFLE DESIGN [message #21674]

Mon, 21 August 2006 21:10

Eddie Munster
Messages: 6
Registered: May 2009

Esquire

I am taking a good look at the P Audio BM15CX38 and the open baffle design at the Common Sense audio site.

http://www.commonsenseaudio.com/paudio.html

I like the size (not some massive bassilla) and it sounds like these are excellent drivers. Has anyone tried them? Any experience with these drivers? Some have said that they are only PA drivers while others say that they are similar to old Altec's.

Any help would be greatly appreciated.

Cheers,

Eddie

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Re: P AUDIO - 15" DRIVER AND BAFFLE DESIGN [message #21675 is a reply to message #21674]

Tue, 22 August 2006 06:31

akhilesh
Messages: 1275
Registered: May 2009

Illuminati (3rd Degree)

Look also at Hawthorne audio. THey have a 15" driver that is recommended highly by some folks who post here. It's also a lot cheaper. THe P audio driver itself is very expensive. Not sure if it;s better, never have seen comparisons.
-akhilesh

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Re: P AUDIO - 15" DRIVER AND BAFFLE DESIGN [message #21676 is a reply to message #21675]

Tue, 22 August 2006 07:07

FredT
Messages: 704
Registered: May 2009

Illuminati (1st Degree)

I have a question. I was under the impression that a relatively high QTS is desirable for an open baffle driver. I looked at the specs for the 15" P Audio drivers recommended for open baffle mounting. The QTS for the BM15CXA is .24, and for the BM15X38 it's .22. These values seem more appropriate for horn or MLTL mounting. Wouldn't open baffle mounting produce weak bass response?

P Audio Drivers T/S Parameters

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How about the T/S specs of the Silver Iris by Hawthorne? [message #21677 is a reply to message #21676]

Tue, 22 August 2006 10:21

akhilesh
Messages: 1275
Registered: May 2009

Illuminati (3rd Degree)

Thanks for ferreting them out, Fred! I was about to look for them and you saved me the trouble. This gives mepause. 0.7 is the magic number for OB (based on my readings, don't ask me why: I don't understand the theory well enough).
SSounds like this Q value is not too great. Next, I need to find the Iris driver Q.
Wonder what that will be. Maybe Mr. Hawthorne can tell us?
-akhilesh

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Eminence Alpha 12 and 15 [message #21678 is a reply to message #21677]

Tue, 22 August 2006 10:28

Wayne Parham
Messages: 18695
Registered: January 2001

Illuminati (33rd Degree)

To do a proof of concept, you might check out the large Eminence Alpha's. They have very high Q, so they'll work well on open baffles.

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Re: Eminence Alpha 12 and 15 [message #21679 is a reply to message #21678]

Tue, 22 August 2006 11:15

akhilesh
Messages: 1275
Registered: May 2009

Illuminati (3rd Degree)

Thanks Wayne. Good tip. I need ot measure my Univ drivers t see the Qt, since i fear it may be too low. Maybe just keep them in the sealed box.

-akhilesh

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Re: How about the T/S specs of the Silver Iris by Hawthorne? [message #21680 is a reply to message #21677]

Tue, 22 August 2006 13:44

FredT
Messages: 704
Registered: May 2009

Illuminati (1st Degree)

The Silver Iris QTS is .91. Apparently they had Eminence modify their drivers to make them more suitable for open baffle mounting by increasing the Q. The QTS for the Eminence Beta 12CX is .48

Wouldn't it be great if we could get Hawthorne to exhibit at the LSAF next May! I'm confident he would generate some sales from this.

Silver Iris T/S Parameters

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Re: P AUDIO - 15" DRIVER AND BAFFLE DESIGN [message #21681 is a reply to message #21676]

Tue, 22 August 2006 16:30

Jim Griffin
Messages: 232
Registered: May 2009

Master

Fred,

Yes, you would need a higher Qts driver or as an alternate very heavy equilization to achieve decent bass from these low Qts drivers.

My warning on most of the Common Sense Audio stuff is that their snake oil descriptions usually exceed the capabilities of what they sale. Just because someone offers you an open baffle box with a low Q driver, don't assume that you will get any bass from it.

Jim

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I know my input is not wanted here... [message #21682 is a reply to message #21679]

Tue, 22 August 2006 17:04

wunhuanglo
Messages: 912
Registered: May 2009

Illuminati (2nd Degree)

But look at the Linkwitz Orion - the woofer Qts is 0.17

You're on the wrong track, as I tried to advise in my earlier post.

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Re: P AUDIO - 15" DRIVER AND BAFFLE DESIGN [message #21683 is a reply to message #21674]

Tue, 22 August 2006 18:58

Jim Griffin
Messages: 232
Registered: May 2009

Master

Eddie,

Let me suggest that you consider the Hawthorne drivers referenced below as they are superior for an open baffle application vs. the P Audio drivers. If I was doing this design, I would use Martin J. King's worksheets (he has a current set that models either one or two open baffle woofers). That approach would get you out of the mystic realm into the objective space of how your project would really work. Plus it will beat the Common Sense Audio approach by miles.

Jim