two BIB questions re inner baffle and driver cutout

drec · 21st December 2006, 09:07 PM

Hi folks!

After the disappointing experience of having bought a pair of Saba 9" greencones and then hearing exceedingly poor performance out of them in OB, I've wiped away the tears and am going uber-cheap-- two 4.5" MCM fullrangers in BIB. Thanks to Gycheng, Scottmoose and others' posts, I've got the dimensions.

Two questions, from looking at Basszilla's gallery of BIBs:

(1) on a couple of yet-to-be-completed enclosures, I noticed that the inner baffle was not as wide as the outer edges. So with the final side being glued on, sound, it appears, would not just travel down and then up the line, but would project directly past the inner baffle because the latter didn't extend fully from side to side. With, say, an interior dimension of 7"(w) x 10"(d), should I make the inner baffle, say, 5" wide or 7" wide so that it creates a sealed 'tunnel' for the sound?

(2) I do not have a router, and so cannot make a perfect 4.5" hole for the driver. On my aborted OB project, I'd read that a perfect hole was imperative as the Sabas were rear-mounted, so I paid $20 for a woodshop to make the holes. Are the parameters for these BIB holes as stringent? Or, can I simply use a compass to draw a circle, drill and use a jigsaw to cut out an approximation of a circle?

Back into the fray... thanks in advance for your response.

Scottmoose · 21st December 2006, 10:16 PM

The internal baffle should be the full internal width of the enclosure to form the horn / TQWT path.

If you don't have a router (I don't either), jig-saw cut it, then get a rasp, file and glasspaper and finish that way. Just as effective, just takes a bit longer and needs more elbow-grease.

gychang · 23rd December 2006, 02:22 AM

Quote:

Originally posted by drec
Hi folks!

I've wiped away the tears and am going uber-cheap-- two 4.5" MCM fullrangers in BIB. Thanks to Gycheng, Scottmoose and others' posts, I've got the dimensions.

I will be eagerly waiting for your thoughts on the el cheapo BIB... A hidden jem in my opinion.

gychang

drec · 23rd December 2006, 02:59 AM

I'm sure they'll be fine. Probably not as aesthetically pleasing as yours, though...

21st December 2006, 09:07 PM	#1
drec diyAudio Member Join Date: Nov 2006	two BIB questions re inner baffle and driver cutout Hi folks! After the disappointing experience of having bought a pair of Saba 9" greencones and then hearing exceedingly poor performance out of them in OB, I've wiped away the tears and am going uber-cheap-- two 4.5" MCM fullrangers in BIB. Thanks to Gycheng, Scottmoose and others' posts, I've got the dimensions. Two questions, from looking at Basszilla's gallery of BIBs: (1) on a couple of yet-to-be-completed enclosures, I noticed that the inner baffle was not as wide as the outer edges. So with the final side being glued on, sound, it appears, would not just travel down and then up the line, but would project directly past the inner baffle because the latter didn't extend fully from side to side. With, say, an interior dimension of 7"(w) x 10"(d), should I make the inner baffle, say, 5" wide or 7" wide so that it creates a sealed 'tunnel' for the sound? (2) I do not have a router, and so cannot make a perfect 4.5" hole for the driver. On my aborted OB project, I'd read that a perfect hole was imperative as the Sabas were rear-mounted, so I paid $20 for a woodshop to make the holes. Are the parameters for these BIB holes as stringent? Or, can I simply use a compass to draw a circle, drill and use a jigsaw to cut out an approximation of a circle? Back into the fray... thanks in advance for your response.

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21st December 2006, 10:16 PM	#2
Scottmoose diyAudio Member Join Date: Mar 2005 Location: UK	The internal baffle should be the full internal width of the enclosure to form the horn / TQWT path. If you don't have a router (I don't either), jig-saw cut it, then get a rasp, file and glasspaper and finish that way. Just as effective, just takes a bit longer and needs more elbow-grease.

23rd December 2006, 02:59 AM	#4
drec diyAudio Member Join Date: Nov 2006	I'm sure they'll be fine. Probably not as aesthetically pleasing as yours, though...