BIB Calculations

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#21
I have seen that 1/2" shelving wood too and thought it was just a bit to thin. On the other hand, hardwoods might be hard enough to resenate. THe thin stuff is worth a try on the BIB as you have the baffle to tighten it up. CHeers.
 
#22
Reducing the size of a cabinet = bad idea. You'll loose LF, and increase ripple depending on the driver and it's Vas. If it's too big, then a different cabinet and / or driver might be a better idea.

1/2in? Don't even think about it -you'll suffer from chronic resonance problems. Even 3/4in is marginal with the larger builds. If you can't get more than 1/2in, then you'll need to laminate a couple of pieces together.
 
#26
davidallancole said:
I will have to go back and see if they were 3/4 inch.
Click to expand...


The panels that I've seen were either 5/8 or 3/4 inch. Available in pine or aspen. Solid wood - even pine - is quite a bit stiffer than plywood and a LOT stiffer than MDF. Aspen is stiffer than pine and would be my choice. The glued up panels will be more stable than a single board, certainly stable enough for a BIB I would think.

Look for a panel that is glued up from full length pieces without any (or many) short pieces butted together.

-- Dave
 
#27
I would like to use this stuff because I could then make a tutorial on building a BIB and it would pretty much be go by the planks from Home Depot, cut to length, glue together. Not many tools required other than a bunch of clamps.

I am going to go to Home Depot and Rona tomorrow to get exact widths, lengths, thickness and what not.

What are you guys listening for when you tap on the wood? Should it not ring to long? Should it have a higher frequency sound or lower frequency?

Thanks.
 
#29
Hi

@ Scottmoose. Can you supply me with cabinet measure/calculation ? Just got 2 old Coral flat 8-II (a friend found 4 of these in the trash...).

Coral flat-8II data (what i can find)

Fo 40hz
Fres 57Hz
Qms 6,9
Qes 0,53
Qts 0,49
Vas 40,2L

best regards Kim
 
#30
Wish I could find drivers like that! I'm afraid completely shot for time at the moment -got another paper to prepare & then I'm back down to Cornwall tomorrow until Tuesday, so I can't do anything refined -sorry. However, if you want me to SWAG it, then I'd go with a 138in line, Zdriver of 30in a la TC's original, and Sl=150in^2. Should do the job pretty well.
 
#34
Hi

GM & Scottmoose.. Do you have a formula so i can recalculate "Zdriver" ?
I tryed recalculating the Line length, 34300cmsek / 47hz / 2 /2,54" = 143.65" this is a little bit taller than the 138" suggested, will this make any difference to the suggested SI (12.43" w x 17.69" d) Or should i just keep the original 138"Line Length/30" Zdriver ?

Best regards Kim Olesen
 
#35
Greets!

A simple formula doesn't take into consideration the terminus' (Sl) end correction, so assuming the WS's SoS = 34,200 cm/sec and 57 Hz Fs, the impedance plot indicates it's the correct length.

That said, if you want to increase the length, then maintain Sl's dims and add 1/2 the difference to 30" to maintain the same driver/floor height.

GM
 

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#38
Scottmoose or GM, what would you use for a height for the FE207E in a BIB? I was guessing around 90" which would be 7.5 feet.

Say I have them pushed up against the back wall (corner has wood stove) and my ceilings are 8 feet tall, would this be to close to the ceiling?
 
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