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11th July 2008, 12:29 AM  #4171 
diyAudio Member
Join Date: Nov 2005
Location: New York

Will pointing the subs towards each other present any problems? Otherwise, great idea. Will you attach them directly to the BIBs or make freestanding cabinets that stand right next too them? Also, will you have one or two subs... in your small room maybe one will be enough?

11th July 2008, 03:27 AM  #4172 
diyAudio Member
Join Date: Jun 2007

Hi,
No, the BIBs are 1.7m in from the corners, I'll fire the subs outwards. Yes, I'm going to attach the subs directly to the existing cabs, they will be well braced. Separate cabs ? I couldn't bring myself to tiptoe a very thin, very tall box of impending doom in the lounge with a five year old running round. I've had two subs for years, run active/stereo, never sounded right with one. Small room, yes, I just don't turn them up that loud (mostly) I'll post some photos when I get the things together. <insert evil cackle here> Sedge. 
18th July 2008, 06:10 PM  #4173 
diyAudio Member
Join Date: Feb 2004
Location: Appleton, WI

some tweakage is needed
I have a BIB abd it's step brother with the double front baffle.
Interior treatment is similar but not identical. The BIB original is giving a better midrange whereas the double front baffle (one cutout 4 in, the interior cutout 5 in) gives the mids coming out the front a muted effect. So suprabaffle on these. I do not think minor surgery such as chamfering the inside baffle would change this. The original 'good sounding' BIB currently has the thin wire tweak on it but here again I think this is minor. Both use FE127e. Both are about the same same size and the newer sibling is closer to the calculator measures. What concerns me is what's coming out the front and less so what is coming out the top. Anyway, the BIB thread lives! 
18th July 2008, 07:28 PM  #4174 
diyAudio Editor

Tomorrow some friends and I are making 10 PAIRS of BOFU BIBs for the participants. We call is Speakermaking Summer Camp. We hope to make them all in a day..
Many participants are younger, so I feel we a re doing a public service getting some great sounding speakers into the world.. Mark
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Next S.F. Burning Amp Festival To Be Announced Burning Amp thread here on diyAudio 
18th July 2008, 08:02 PM  #4175 
diyAudio Member
Join Date: Nov 2005
Location: New York

>>> Tomorrow some friends and I are making 10 PAIRS of BOFU BIBs for the participants. We call is Speakermaking Summer Camp. We hope to make them all in a day..
>>> Many participants are younger, so I feel we a re doing a public service getting some great sounding speakers into the world.. I am sorry to have to miss this. Very cool indeed! If you take pictures please forward them to me. Thanks, Godzilla godzilla3@hotmail.com 
18th July 2008, 08:59 PM  #4176 
diyAudio Member
Join Date: Aug 2006

"The BIB original is giving a better midrange whereas the
double front baffle (one cutout 4 in, the interior cutout 5 in) gives the mids coming out the front a muted effect. ...........................Both use FE127e." Have you tried switching drivers from one cab to the other ? Also, don't discount small changes such as wire , sometimes it makes a BIG difference. ..........................Blake 
18th July 2008, 11:41 PM  #4177 
diyAudio Member
Join Date: Jan 2007

Lon, I know you mentioned that the two cabs are roughly similar, but I'd suspect the stuffing / felt / foam, since it's easy to overdamp. Just a thought!

19th July 2008, 01:33 AM  #4178 
diyAudio Member
Join Date: Feb 2004
Location: Appleton, WI

I hear your suggestions but what I don't understand about the
stuffing materials is how that would diminish the mid tone coming out the front. For instance: clarinette solo is forward on the one and lost in the tympany on the other or something similar. The Lost In Translation BIB with the double baffle front has thin foam behind the driver, fiberfill in the peak and egg crate foam on the bottom. The Original has fiberfill in the peak, billiard felt behind the driver and layered fiberfill (very loose) about a 1/2 inch on the bottom. The cabinet material differs on the sides: butrcherblock glue up pune (prefabe shelving) on the Original, less than void free plywood on the troublesome one. To be honest, I tore down one nonBIB build and reused the plywood just so I could see what a couple of BIBs sounded like together. Considering my usual asymmetric listening style, 2 bibs at close range may just not be a good fit. Next round of building is an MLTL. The plywood BIB I may set up as part of a different rig in a testing/build room. 
21st July 2008, 03:37 AM  #4179 
diyAudio Member
Join Date: Jan 2007

BiB Spreadsheet / Calculator Gotcha
I love the BiB spreadsheet. However, there is one gotcha that I noticed tonight in assembling my FE166E BiB's.
In attempting to get the abc lined up correctly, I ran into trouble  the divider was too long. In OpenOffice, I checked the formula calculating the slant (divider's) length. My driver happens to be in column F, and the slant length is calculated in cell F41: =(IF(F21=0;"";MROUND(SQRT(SUMSQ(F30(F13))+(F13));0.25))) So the formula states: If F21 (material thickness) is zero, return an empty string (nothing) to avoid dividing by zero. But otherwise, calculate the length of the divider according to the Pythagorean theorum (hypotenuse = sum of the squares of the other sides in a right triangle). To do that: 1. Take height (F30) minus the abc value as one of the sides. Let's call this "a". 2. Take abc value (F13) as the base, and let's call this "b". 3. The slant's length (call it "c") is equal to the square root of (a^2 + b^2). 4. Round the result to the quarter inch. The slight issue I noticed is that item #1 fails to account for the .75" of the base. The base is mounted "inside" the other four boards. So really, .75 needs to be subtracted from external height. If not, then when you are gluing up, you'll notice there's no way to get your abc to come out right. However, the fix is simple: just nudge the divider up until you get your abc (north of the mouth), then trim off that excess. So I'd recommend changing the above formula to: =(IF(F21=0;"";MROUND(SQRT(SUMSQ(F30F21F13)+(F13));0.25))) Empirically, when I nudged the divider "higher" than the mouth, until abc worked out, I got 61" and that's what the revised formula yields as well. Anyway, thank you to all who worked on the BiB calculator  it's terrific! 
21st July 2008, 04:34 AM  #4180 
diyAudio Member
Join Date: Jan 2007

One last thought:
Technically, the base of the triangle (of which the slant is the hypotenuse) is not the value of abc, but rather, the value of abc minus 1/2 of the slant's thickness (material thickness, F21). This is because the abc "pinpoint" is located at the center of the divider's bottom (at the midpoint of the divider's thickness). But the slant is the hypotenuse of a triangle with a very slightly smaller base (smaller by one half of the slant's thickness). So we could say subtracting half the slant's thickness is more accurate: =(IF(F21=0;"";MROUND(SQRT(SUMSQ(F30F21F21/2F13)+(F13));0.25))) But it's not, because of rounding. For the FE166E, it becomes 60.5 whereas empirically, 61" is more like it. This is because the formulas are ultimately doing multiple roundings, i.e., using a rounded value to derive another value, which is then rounded. Anyway, I really do love the BiB calculator  it's a great time saver and a huge help for those of us who can't measure and cut too well. Thank you again to all those folks who have worked on it, directly or indirectly! 
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