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

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#5,281
I have a Fostex FF165k BIB that I made a few years back using dims from the BIB calculator. After having the drivers "modded" by my two young boys I was wondering how the following drivers would do in the cabs:
Omnes Audio BB4.AL (CHR70 variant)
Fs68 HZ Re3,6 Ohm Vas4,2 l. Qts0,55 Qms2,0 Qes0,75 Sd50 cm² Mms4,68 g x-max4,5 mm SPL84,5 dB Bl 2.99 T/M
Levc 0.43 mH R 1kHz 5,0 Ohm R 10kHz 7,5 Ohm

Alpair 12 (1st gen)
Revc= 7.000 Ohm
Fo= 46 Hz
Sd= 143.14 Cm
Vas= 22.8 Ltr
Cms= 0.750 MM/N
Mmd= 14.886 g
Mms= 15.871 g
BL= 8.752 T.M
Qms= 1.454
Qes= 0.420
Qts= 0.327
Levc= 0.058m H
No= 0.493 %
SPLo= 89.3 dB
Xmax= 9mm (1 way)
Pwr cont= 50 watts

The speakers are powered by a gainclone built from an Audiosector kit or an Amp Camp amplifier. Thanks for any insight.
 
#5,282
There's probably no particular reason why the original Alpair12 (metal) couldn't work well enough in an appropriately dimensioned BIB, but from what I can remember of that driver, it could work in a much smaller MLTL, and you might want to consider adding a small tweeter - the latest generation A6M or even the upcoming CHS40

http://www.diyaudio.com/forums/markaudio/261291-chs40-chs50-early-developments.html

I'm not sure if Mark has determined yet if these new sizes will be offered in both paper and metal - personally, I'd be inclined to use the same material for all drivers in a multiway whenever possible.

The Audiosector gainclone is an excellent sounding rig, and by all accounts the same can be said of the ACA - I'm hoping to have mine together within the next few days.
 
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#5,288
No problemo! Not your responsibility and appreciate what all you have done with the BIB project!

Ye gods! This still going on?! Seems like it's been years........ Sorry you didn't get custody, hope the court doesn't gut you the rest of the way.

GM
 
#5,290
Thanks gents! Yes, nearly 4 years of divorce maddness. When it's over I'll participate more frequently on the forum - I miss it!

I have two pairs of BIBs (165k and 127e) and love them both. I hope to at least get the smaller pair. I was able to fit the Open Baffles into my car and drive off. H-frames are easy to transport as are the top baffles that sit on top of them.

I've already sketched out a few projects that are more apartment friendly using some of the wonderful and endearing older full range drivers I have. For example Fostex 168z, Radio Shack 1197 and 1354. I have 69 cent wonders and NSB's from PE. Betsy's, TB's and Beta 12lta's... honestly, I'd buy them all again if I lost them just to learn about the hobby. Considering it's been several years, the cost is really not expensive.
 
#5,291
Thanks for the replies. The plan is for the A12's to eventually go into Pencils or Super Pencils so just looking for a drop in to the BIB that I have. Will check the dims tomorrow but they are BIG.

I have tried the AL4 in my little fe108es BIB's but they definitely need more room to breathe. Having said that they put out some real bass with both a gainclone and the ACA. What would be effect of having too much volume in this case?
 
#5,292
Godzilla said:
Thanks GM. Sorry I didn't respond to your email gychang. My divorce trial is Tuesday and I've been preparing for it. BIBs will stay in house with my two boys and their mother. The OBs were easier to carry out of the house.
Click to expand...

Holy Smokes!

I had assumed your divorce went through a few years ago! I hope everything works out as well as it can for you!

Best Regards,
TerryO
 
#5,293
giantstairs said:
Thanks for the replies.

I have tried the AL4 in my little fe108es BIB's but they definitely need more room to breathe. Having said that they put out some real bass with both a gainclone and the ACA. What would be effect of having too much volume in this case?
Click to expand...

You're welcome!

No clue what an AL4 or ACA is, but obviously, it will have less peak power handling over a wider BW, but assuming the driver has a rising rate suspension, then it might handle a watt or two since the sheer volume of pipe/horn action acting on it will damp it somewhat.

The downside is it may be enough to audibly modulate/over-damp its mids/lower HF response. Only one way to know for sure though.

If you try it it, please let us know how it performs as the only experimenting I did on horns tuned way below driver Fs was using a compression driver on an expo BLH.

GM
 
#5,294
Sorry, I meant the Omnes Audio BB4.AL that I had referred to earlier. I think I will try them but do not want to damage what appear to be delicate drivers. A better option would likely be two of these per cab, but then I would need to hack apart the front of the cabinets.

The ACA is the Amp Camp Amplifier that I built a few months back.
 
#5,295
The ff165k BIB that I built measures 110sq in with a line length of 160 inches. I'm pretty sure I used the BIB calculator V1 to get these dimensions.

Plugging the numbers into your V2 calculator I see that the cab is too large for the Alpair12 (86 sq. in.) and way too large for the BB4.AL (30,3 sq. in.) with this line length.

Besides possible bad sound is there any risk of damage to the smaller drivers at moderate volumes?
 
#5,296
BIB dimensions

I hope this thread hasn't died because I am planning a BIB enclosure for my Lowther DX3's. They have been in ML TL (Martin King) enclosures I built for the past 8 years.

I have attached a Jpeg of my plans although the basic measurements are:

Hight 180cm
Depth 39cm
Width 28cm
I missed the x driver on the drawing which will be 76.5 cm

My question is will this be okay, the room is about 8 x 5 meters and 2.4 m high.

Thank you,

Iain Bowman
 

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#5,298
I wish I could take credit for it, but back in the early '60s I saw one made from rigid fiberglass insulation mounted at an angle in a circa 1950 Altec triangular compound horn cabinet as an interesting way to damp its floor firing vent.

GM
 
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