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

[GM]

Greets!

You're welcome!

take three :

http://gallery.audioasylum.com/cgi/g...TSHACKBIBS.JPG

GM

[xstephanx]

sorry mods but what needs to be done needs to be done!

scottmoose, please check your email, i fear it has once again put me in the wrong folder! if you actualyl dont have any emails from me(which you should) PM me and ill send it again. youre the only person i knwo of that can answer my question!

[lovechild]

Originally posted by GM
Greets!

I haven't read all of the thread either, but I assume you're referring to the fact that none of MJK's freeware WSs will show the effects of the room beyond an infinite half space loading, which is all Scott has been publishing even though he has the licensed WS that allows a certain amount of room loading and floor bounce modeling.

Anyway, as you can see, the freeware BLH WS sims more than 'close enough' to his latest shareware ML-TQWT WS by inputting the BIB's design into the BLH coupling chamber fields and listing the horn length as 0.001, with St, Sm = SL, and linear flare rate.

GM

Hi

I tried to model the BIB using MJKs shareware BLH worksheets but did not succeed. GM, as I understand your post, you suggest to model it using the coupling chamber only, with the horn set to null? I tried that, but it doesn't work at all, for me. Any suggestions?

LC

[GM]

Greets!

Don't have a clue. Look at my master '.mcd' to confirm you inputted it correctly:

GM

[el`Ol]

AJ-Horn would have room interaction, but is more expensive than MJK`s sheets.

http://www.aj-horn.com/indexe.htm

[lovechild]

GM, thanks alot, now it works and I have no clue either why it wouldn't work before - I must have missed somthing.

@el' Ol
AJ Horn will modell corner loading but does it take account of the upward firing mouth?
MJK's reflected on that point in a post at the beginning of this thread (see below). His new worksheets allow (back)wall and floor loading, and port/mouth on the front or rear baffle, maybe he will come up with the up- and down firing port sometime?!

best,
LC

Originally posted by MJK
Just got back from my evening walk, I think my wife is trying to kill me, and I was thinking some more about the Terry Cain pipes.

The location of the open end is very interesting and probably the reason the simulation looks so bad. But as you report the real response seems to be much better. Two points probably contribute to this difference.

First, with the open end backed up against the wall the effective mouth area is doubled, due to the reflection boundary condition at the wall, and this will allow lower frequencies to be more efficiently transferred into the room (the resistive portion of the acoustic impedance is doubled). At the same time, less energy is reflected back into the line reducing the magnitude of the standing waves. So more bass output and attenuated standing waves compared to the simulation results.

Second, by pointing the open end up you are listening over 90 degrees off axis. With the mouth output reflected off the wall, the depth dimension effectively doubles while the width remains the same. This shape is going to become very directional with increasing frequency so the ragged response predicted above say 300 Hz is probably grossly over estimated.

Two interesting properties not accounted for in the current MathCad simulations. My newer worksheets are starting to account for these issues, along with the baffle step, and include them in the final calculated results.

context

[Godzilla]

http://www.zillaspeak.com/bib-fostex.asp

Fostex 125, 206, 207, 206esr and 225k.

More BIB's from Scott! Please wait for graphics to load. This page became long. Let me know if all the images load too... thanks!

BTW, Scott.... should the line length below be 178 or is 78 correct?

Fostex FF225K
L = (Line length) 78"
Zdriver = Driver 35.75" down from sealed end of cabinet
Sm = 126"^2

Thanks,
Godzilla

[uvellani]

I was thinking of trying one of the other(more expensive) 4/4.5 inch fostex drivers in the BIB I built for the FE126E. Specifically FE108EZ or the FX120. Do you think they will perform reasonably well with the dimensions posted for the FE126E BIB? Physically they are very close in size and should fit without modifications.

Thanks
UV

[Godzilla]

uvellani send me an email at godzilla3@hotmail.com for the 108 dims.

Peace,
Godzilla

[TC]

In LA at the HE2006 rm 317, is a pair of fe 108ez I-BIB being demo'd .

TC