Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

[GM]

Originally Posted by Vix

Could anyone please check and confirm, are those dims correct?

If the specs you inputted are correct, then so is the dims.

That said, for a ~ 96" ceiling height, I'm reluctant to use a pipe horn shorter than T.C.'s [48.78 Hz input] and if I can ever get back to DIYing speakers, plan to put my 125s in it [even same ~55"^2 'Sm'] and experiment with various shape 'tophats' to mass load them a bit plus better couple them to the ceiling.

GM

[Circlomanen]

Even small leaks tend to cause the speaker to unload enough to self destruct except at very low power,

I think there is some leaks around the driver. Im not worried about destroying the drivers. I have been giving them 250 watts each on several occasions. No excessive excursion or distortion, only VERY VERY VERY loud! Everything in my house was vibrating and flexing. The walls moved back and forth over an inch at some places. The frame of my house has a tone/resonance, that can be heard if i suddenly pause my CD-player.

They sound lean, but its only a matter of balance. I will glue on another layer of plywood and fasten the drivers with bolts and T-nuts. I hope it will "cure" the somewhat lean character.

I think the BIB is a great kind of speaker. I want to build another pair with my Beyma 12P80Nd, but my gilrfriend does not like that. It might be a project this coming winter.

Regards Johannes.

[Etocynned]

Making some bibs for a cousin as a house warming gift, thinking of MA's from CSS because its close by.

are all MA drivers 4 ohm?
If so can i use 2 in a bib and use the point between them as z driver?

how would TS parameters work out if they were in series?

[GM]

No, most are 8 ohm.

Yes.

Re, Le, Vas sum, the rest average out.

GM

[Circlomanen]

I have a pair of cheap car-audio coaxial 6,5 inch driver that i want to BIB. My kids want some rock ´n roll speakers with decent bass on the cheap.
I have absolutely no idea what Qts/Vas/Fs is, but i know the BIB is very forgiving and tolerant of different speakers.

Should i just simulate some other cheap high-Qts driver of the same size and hope for the best?
What is a good size to get some real thump from the BIB?

Johannes.

[GM]

Well, I wrote a long history of what I use to do when there were no specs except Fs, but all things considered, I guess that just making a scaled version of TC’s original BIB to accommodate the larger driver by assuming it has a ~138” path-length [assuming a ~8 ft high ceiling] and a ~1.0 Qts should make it large enough, which just happens to work out to ~11.64 ft^3, very close to my earlier way of doing pipe horns at ~11.055 ft^3.

height (in) 69.006
depth (in) 20.303
width (in) 14.356
A-B-C (in) 10.152
driver offset (in) 29.949
driver offset - sub (in) 59.898
driver height (in) 39.808
driver height - sub (in) 9.859

L (in) 138.013
Sm (in^2) 291.479
net Vb (ft^3) 11.64000

baffle thickness (in) 0.750
zdriver 0.217
zdriver - sub 0.434
Fs 48.78
Vas (ft^3) 0.5820
Qts 1
SoS (in/sec) 13464.54

This should make it large enough to allow sufficient in-room tuning flexibility.

GM

[Circlomanen]

Thanks GM!

I will probably build them this fall.
They want to listen to Kiss, Deep Purple, Metallica and Rammstein. They will probably use them as a soundsystem when playing Team Fortress 2 and Half Life 2 on their computer. Nothing like some good low end thump when blasting someones head of with a rocket launcher!

Johannes.

[GM]

You're welcome!

Please post here how they perform and how much EQ was required to protect them.

BTW, what brand/model are the drivers?

GM

[Circlomanen]

Now both my big BIBs with B&C 10PS26 bass/midbass drivers are playing. I think they sound wonderful! There is some slight coloration. Nothing to annoying, but there is something slight there. The have a very full and powerfull bass. Very "fast". They start and stop a bass-note very fast. No decay or room-resonance. They seems to dominate the room-acoustics in some way.

Im very pleased! Now i just have to ad tweeters. I have some different ideas there. Maybe a 3 inch fullrangedriver with a 6 dB active filter @ 600 - 1000 Hz somewhere.

Thank you everyone that have been contributing to this thread!
Thanks GM and Godzilla! You have done so much to make the BIB known!

Johannes.

[BenjaminWebber]

Do Post some pictures!