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

[GM]

Greets!

TB W3-871S (PE #264-813):

L = 70"
zdriver = 15.2"
Sm = 22.5"^2

Due to the high Fs and driver position, I recommend floor loading it.

GM

[el`Ol]

Originally posted by Scottmoose

In case anyone has been wondering, the highish Fs of Visation's FR drivers (except the B200) is why I haven't bothered doing any sims for them. Wish they'd come up with a 6 1/2in version of the B200. That really could be very special indeed. Are you taking note, any Visation engineers? I'll look into those other 3 shortly as there's a request though.


Cheers
Scott

I guess that would be really fine for people who don`t have the opportunity of corner loading. I simulated the Ciare HX160 in a 340cm BIB with the TL offset driver sheet. In contrast to the half wavelength TQWT (250cm, 50Hz) it would probably need corner loading, but it would still be there at 40Hz.

[zek]

Originally posted by GM
Greets!

BG20:

L = 178"
zdriver = 38.63"
Sm = 330"^2

Due to the driver's low Fs and low Xmax though, I recommend going with a shorter pipe:

L = 138"
zdriver = 30"
Sm = 330"^2

The FR6.5's super high Qts is way too high to work in a BIB.

The FRS8's Fs and Qts is high enough that it's probably better to turn it upside down and floor load it:

L = 65"
zdriver = 14.1"
Sm = 22.5"^2

GM

Thanks GM for yours sims.
I see that Visaton drivers are not so good for BIB enclosure (except B200), and I have to find something better suitable (maybe Monacor SPH-60X)

[Scottmoose]

Cheers Greg, you beat me to it with those!

Zek, my Monacor BIBs are currently playing in the garage and they work very well indeed. The little SPH-60X is a cracking driver, and well worth pursuing.

Re the flare rate, Greg has already refered to this in previous posts a few pages ago. I can't remember which number off the top of my head though. Have a search and you should find them quickly enough.

[fred76]

GM wrote:

BG20:

L = 178"
zdriver = 38.63"
Sm = 330"^2

Due to the driver's low Fs and low Xmax though, I recommend going with a shorter pipe:

L = 138"
zdriver = 30"
Sm = 330"^2

Hi,

It is my understanding that highish Fs drivers are more suitable for an Inverted BIB.

But here are some questions:

- Do low Fs and low Xmax drivers also benefit from a shorter pipe when used in an Inverted BIB? Example, 56Hz Fs and 1mm Xmax from the Veravox 7x.

- Zdriver is adjusted when pipe is shortened for a “Normal BIB”. I'm just not sure if/how this applies to Inverted BIBs and what variables are involved (?).

I'm uncertain which drawing below is correct. But I surmise it's the one on the left? Thanks!

fred

[edjosh23]

fred76,

I'm about to go out and get wood for a pair of BiB's for my 871s. I'm have designed a floor loading enclosure similar to the BIB on the left in your picture.

GM,
Thanks for the specs. By the way, the manager said to come back next summer, but that I was going out of town too much this summer


Josh

[doggy]

good morning all

I have a pair of ff165k that are broken in and I have built the bib cab according to scottmoose's cab of 8.5x16.25 external using 3/4" poplar plywood; 7-7-7 at the bottom for the internal baffle and 69" high.

The other driver I have and will try in this bib is an eminence alpha 6". It is not very refined but a good performer and robust.

How critical is the driver distance from the bottom base? Scottmoose indicated 36". What are the effects of moving it up to 38 or 40" up, given that there is enough clearance behind the driver?

Thank you scottmoose and everyone involved in the bib.

cheers
doggy

[fred76]

Thanks edjosh23.

Yeah, the drawing on the left chops off the actual terminus at an angle, thus shortens the recommended pipe length - not right.

I'm still curious if a driver with 56Hz Fs and 1mm Xmax will work with a shortened pipe... Zdriver will be adjusted (I think higher) when pipe's shortened for a normal BIB... If the BIB is inverted, the driver postion becomes low, so an extra pedestal is needed to get the driver position circa ear-level .

fred

[doggy]

Well, I settled for 37" from top of base to speaker. Cab is 3/4" poplar. Still have to finish 2nd bib,then sand and apply clear nit. lac.

Have to make more room for the bib. The ff165k sounds clear and dynamic in this cab. Have not added any internal damping yet.

cheers
doggy

[Scottmoose]

Good man. They look very nice indeed from the pictures. Poplar? I don't think anyone's tried that before; could be good. Certainly looks the part!

Driver distance is really taken from the sealed end (the point), and is usually placed to help supress a null in the response. Given the reliance of these these enclosures on the room however, I don't think moving their position an inch or so from the ideal will have drastic consequences. Experimentation is the key! (within reason). It sounds like you've used my original dimensions with the larger terminus, and lower driver. The latest, available on Godzilla's wonderful BIB pages, have a smaller terminus and higher driver mounting. There shouldn't be much in it, especially as you've lifted the driver up a bit. In fact, if anything, you'll probably have better LF response. I might play around some more with the 165 dimensions for the 'Zilla pages -a combination of the two perhaps. The drivers are worth it. Enjoy & keep us posted.

Regards
Scott