BIB size adjustment

[gychang]

According to BIB calculator, using Pioneer A11, outside dimensions are 10.5"x8" (using 3/4" plywood), with the height of 49".

I need to change 10.5" to 9", how much does the width need to change?, may violate the "golden rule"... I already have the speakers and the size has to be 9" deep since it will be fitted into a wall cabinet that is 9" deep. (will be putting the speaker wire connector from the sides).

thanks,

gychang

[Godzilla]

9.5 wide x 9 deep by 49 tall should do the trick. I rounded up a little. I do not think the golden ratio will make any audible difference in this case due to all the other variables in a typical room. Maybe someone can check my math please. Also, make sure when reducing the depth of a BIB that the inner baffle will not be in the way of the back of the driver. Check twice before cutting the wood.

Godzilla

[bassrogue]

Mine are 11.5"x 8" outside with 3/4" material.. The beer must have been flowing freely that day. They work OK though.

[gychang]

Originally posted by Godzilla
9.5 wide x 9 deep by 49 tall should do the trick. I rounded up a little.

Maybe someone can check my math please. Also, make sure when reducing the depth of a BIB that the inner baffle will not be in the way of the back of the driver.

Godzilla

Thanks Gozilla:

This cabinet size wil be much better for me, 9.5Wx9D...

Almost didn't think about the inner baffle, have to make sure there is clearance in the back

gychang

[loninappleton]

The workaround for depth of speaker would be the suprabaffle or
or a double baffle.

I have done this another way as well: made a block at the peak end
but kept the taper to the a-b-c measurement.

To my ears, the single baffle shimmed out is better than double baffles. Making the shim was just a patch for a cabinet already built.

If the new calculator measurements account for driver depth but you have to change the measurement, adjusting the top is likely less important than a-b-c.

[s_zimble]

I am considering either the FE168EZ or the FE208EZ drivers in a BIB enclosure but the potential size does give pause. I read in another post that the required (optimal??) tube length for the 208 actually is shorter . Is this true. And are these drivers well suited for this type of design?
Zilla? can you give some small guidance or opinion on driver and enclosure size? Also, I have been researching past posts on this topic and read that there were some more recent modifications that you and Scott have made to improve aspects of this design (ripple/comb filter reduction, etc...). Are these all incorperated on your site along with plans??

Cheers, Stuart

[DaveCan]

I thought about a 208 BIB also, but with 13.3576 feet of line length I'm thinking there would be some serious delay issues, same with all the larger cabs I wonder?.. You can bet you'd have some serious low end grunt, but if the arrival is off then? I wonder if this has been much of a factor for listeners of these larger driver cabs?
Dave

[s_zimble]

Hi,
Indeed delay is an issue to consider, but I think this would have been mentioned more in the previous discussions if it was that noticeable in practice. Perhaps Scott, Zilla, or GM would have something to add on this.
Even with the strange math contradictions, I have heard that this driver and this enclosure can have a very pleasing result.

Anyone out there have comments of whether there is a delay issue and how to deal with it? Otherwise, other enclosure suggestions?

This Driver is supposed to be built for a BLH. The BIB is not a BLH, but I conclude that it acts as a strange hybrid TL, TQWT, and BLH, but without a compression(filter?) chamber.

I have a self-designed BLH for a FE103 (on paper) that I thought could be sized up for the 208EZ but I am afraid the weight of the 208 may be a bit much for this particular shape I have in mind. I may take the horn length and chamber dimentions from the fostex suggested enclosure and use it for my own creation.....

I also wanted to avoid the tweeter addition, but from what I read, it may be a serious consideration for this driver.

Stuart

[GM]

BIBs are simple horns with offset drivers, so yes, there will be audible out of phase issues if damping to limit mids/HF output exiting the mouth isn't used to offset the lack of a proper filter chamber. Then again, some folks like letting some out for its added ambiance, so as always YMMV.

WRT length, the standard is to tune it an octave below Fs, but ceiling loading is more important, so if it calcs < TC's original I recommend lengthening it to at least match it in height, which of course will make the cab bigger in cross section also.

GM

[Godzilla]

>>> Then again, some folks like letting some out for its added ambiance...

Yes, me likey that way. But you can have it either way with BIBs which is nice.