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

Well, Scott - completely OT from your above musical recommendation, but I thought I should share a recent find with you.


I recently came across a DVD/CD combo package (1 DVD and 2 audio CDs) of Loreen McKennit "Nights at the Alhambra" - recorded Sept '06.
This must have been on the same tour of which we saw the bookends. Of course even though Victoria's Royal Theatre is a world class venue renowned for it ambiance, acoustics and abundant washrooms :whazzat: , it somehow doesn't measure up to a 16th century open air Spanish castle.

to relive virtually the same concert performance set was worth every penny of the $23 at Costco - and the close ups of Caroline certainly tests the resolution of your DVD player's pause function.

At full tilt, this astounding group of musicians, who certainly appear to enjoy the hell out of playing together, can test every aspect of any audio system - the little (Enabled) FE127E in Mileva or Fonken enclosures certainly giv 'er everything they've got.

cheers
 
Oh, yes, Nights from the Alhambra! Chris, you are a man of taste. How did I forget to mention that? I bought mine back in April on the tour, before it was released to the public. You're not kidding Chris -it's up to and beyond Loreena's usual sensational standards. :worship: That whole group gel beautifully, and they obviously love playing together, which is so important to live performances, as you say. Fantastic recording quality, both sound and visual. Caroline does provide some additional eye-candy too, which is a bonus. ;) A bargin at double the price IMHO. Bet those Fonkens lap it up too. Perfect hunting ground for a high quality small driver. You need a system that can do imaging to do this recording justice.

I'm now off to try it through the BIBs before the boxes have to go back into temporary storage. :)
 
Well, this is other of the things that refrain me of taking the plunge and building the FE166E BIBs...
I now have FE108EZs in Fostex recommended spirals for FE108Z and really love their mids, but also having flea powered SET amps, the extra SPL is a needed bonus, and the bass department of the FE108s is limited... Frugels are out of question WAF-wise.
Dunno... perhaps I should start investigating a flat spiral for the 108s... like the Cornus and the Walla-Wallas... it won't get me more SPL, but better bass...
Or perhaps "enabling" the 166Es will make the difference worthwhile...

:confused:

Gastón
 
frugal-phile™
Joined 2001
Paid Member
resident said:
Isn't this a nice emmmm, BIB? :eek:
Or not? :confused:

No, a larger, upside down BeauHorn B2. A shame they are hiding all the curves with those big side panels.

aion_cons.GIF


An externally hosted image should be here but it was not working when we last tested it.


dave
 
germpod said:
Any ideas on how close to the ceiling the top of the enclosure can get without negative effects?

Greets!

Well, the closer to the ceiling it is, the greater the slot loading, so from this POV it would have to be very close indeed to be too close. If you mean to keep it from being slot loaded, then at minimum it has to be beyond the pipe's acoustic length at whatever the driver's max low distortion excursion is, so no set distance.

BIBs typically have a large enough terminus and use low enough suspension limited (Xsus) drivers though that a pipe's end correction formula is probably sufficient, so calc the mouth's effective radius, then Dmin = > radius*0.613 and > 3*radius if you want no doubt.

GM
 
GM said:
BIBs typically have a large enough terminus and use low enough suspension limited (Xsus) drivers though that a pipe's end correction formula is probably sufficient, so calc the mouth's effective radius, then Dmin = > radius*0.613 and > 3*radius if you want no doubt.

Hi GM... I assume the effective radius of the mouth would be the radius of a circle whose surface is equal to the effective one of the mouth of the BIB. If so, then

eff radius = sqrt( D x W / pi )

now... why 0.613 ?

Greets

Gastón
 
ghpicard said:


Hi GM... I assume the effective radius of the mouth would be the radius of a circle whose surface is equal to the effective one of the mouth of the BIB. If so, then

eff radius = sqrt( D x W / pi )

now... why 0.613 ?

Greets

Gastón


The 0.3*diameter or 0.6* radius is the 'standard' end correction for open tube resonance. You can find an introductory discussion here


http://physicsforums.com/archive/index.php/t-166445.html

RKH
 
Hi GM!

Where would you start with something like that?! A compression chamber with a BIB.

I know this is over simplistic to the max or maybe just a dumb question... but does the size of the compression chamber remain the same for a specific driver and just the line length changes according to how low you want to go or does it all work in together....

For the fe168e sigma in a bib, line length is around 132 inches, with an Sm of around 81 sq inches. Zdriver at 28 inches for end. I understand that a BIB is a tapped horn. So I presume that I can't just stick a compression chamber on the end of this and expect it to work!

I think this could get real tricky...

What improvement could be expected if any, with compression chamber as opposed to the BIB.

It just seems it could be only mildly more difficult than a BIB to build!

Cheers Stroop
 
It's a filter chamber, not a compression chamber. For a BLH, the room is the CC. The filter chamber simply determines the upper cut-off frequency of the horn. There are lots of ways to determine it's volume, Leach's, Keele's etc., and frankly the pre T/S alignments such as V=2.9R*At generally work as well as anything else.

In terms of benefit, it will mean the cabinet will roll off at a specific point (more or less) rather than not having a limit, the upper frequencies being damped out by the bend and stuffing / lining. Downside, they're a little more complicated to build & get working right.
 
Hi Scott!

Oooops er yeah thats what I meant!!! Filter chamber...filter chamber...filter...

Scott that's really cool! But I'm an idiot and have no idea what that equation translates to! I know you don't have time explain either and thats ok!!!!!

Pretty tricky to work out then.

Would it be a simple case of taking an existing horn enclosure that works and then straightening it out to fire to the ceiling....I know its cheating...but as a starting point? er... provided it is not one of the exponential types which would then be also tricky to build.

Cheers Stroop