Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 181 - diyAudio
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Old 22nd November 2006, 02:43 PM   #1801
dmason is offline dmason  United States
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Layne

I am sure Scott will get back with some dimensions, but one thing I can say is that the Fs/Qts are "BIB qualified" for sure.

Second thing I can think of is that where the BIB loads the vertical mode, its presentation in the lower register is pretty much indistinguishable from dipole. Others will concur. There were three people with their own DarkStars that I built for them, whose initial comments about the BIB168 were on exactly this phenomenon. Therefore, I find BIB's to be a better solution to that "addiction" than OB itself, doing away with large-and-in-charge baffles, which are not room friendly in the least, and possibly with multiple large diameter bass drivers.

Given that F's > ~1500Hz are direct-radiated, I figure you will get what you were after anyway, and that a BIB is the answer. I would bet the Veravox would be even better.
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Old 22nd November 2006, 03:13 PM   #1802
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Dan

I keep coming back to the BIB as a strong solution, as it makes sense for our current space. Being that I have the drivers for the other direction, (OB, supporting the low end with a bass driver) I keep trying to think of a way to make that work.

I remember when I took the 168s out of the poorly built BIBs and put them on an OB, I didn't notice much difference, (bass aside) as I had expected. The BIBs really do off a natural, balanced sound.

I suspect you are right and the 7xs may be a good candidate for our beloved BIB. Being that the magnet is deep, I may need to add some sort of chamber on the front, as I don't think an add on baffle will do the trick. We'll see, once we have box specs.

Lp
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Old 22nd November 2006, 03:58 PM   #1803
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Trying to keep up is the problem as I've a bit on at the moment, so please accept my apologies if I'm a bit slower than usual in answering any queries. I'll try to get some suggestions for these done over the next few hours though.

Scott
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Old 22nd November 2006, 04:07 PM   #1804
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No rush Scott, take your time. Thanks for the effort.
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Old 23rd November 2006, 08:08 AM   #1805
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I posted this on the other thread too: suggested dims for Veravox 7x BIB:

Line length 140in
Zdriver 29in
Sl=150in^2

It's got to be pretty big compared to, say, a cabinet for a similar sized Fostex unit because Q / Vas ratio is high. Not a bad response at all though.
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Old 23rd November 2006, 08:21 AM   #1806
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HX160 BIB

I've had to fuge it slightly as I can't get hold of the Re. However, it shouldn't affect the response much other than the shape of the roll-off. I took it as an arbitary 5.0 ohms.

Line length 120in
Zdriver 25in
Sl=82.775in^2
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File Type: gif hx160.gif (6.5 KB, 390 views)
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Old 23rd November 2006, 08:32 AM   #1807
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Seas T18 co-ax BIB

Line length 160in
Zdriver 34in
Sl=82.75in
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File Type: gif t18.gif (6.7 KB, 395 views)
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Old 23rd November 2006, 10:04 AM   #1808
stroop is offline stroop  Germany
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Thankyou Scott!

Brilliant work!!! The response of the veravox looks good! Just a question though, what makes a response so jagged, say veravox compared to the HX160 or Seas. More to the point how much of that squiggly line do you hear? Some of the dips are down to 75db...

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Old 23rd November 2006, 04:11 PM   #1809
mrbubbs is offline mrbubbs  United States
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Scott,

What would you predict the difference be in sound if the 2001 monolith enclosure was 96" in height instead of 72"? Just curious. I am going to reduce my wood requirement by using my wall as the back of the enclosure. I plan on putting "feet" so that the thing doesn't tip forward by an external force. Probably 16", double the depth of the cabinet. This would end up bumping the driver 3/4" in height, of course. Using my crappy math skills, I figured the internal baffle would be ~59" in length. I'm also pondering a 16"x16"x3/4" extra front baffle or maybe just doing a smaller round baffle as seen on the Cain enclosures.
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Old 23rd November 2006, 04:52 PM   #1810
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If you increased enclosure height you'd extend the bass, probably by another 10Hz or so, and flatten the curve out somewhat as you've also got a fair bit extra box volume. However, the driver would be about 2ft over your head, unless you listen when sitting on a tall bar-stool. Not a terrible problem of a huge driver, but a trifle excessive for anything smaller... I chose the external dimensions for the monolith specifically to match the 1x4x9 ratio of the Monolith Kubrick & Clarke dreamed up, without needing to go to an excessive number of decimal places. You could do (external dims) 10in deep x 22.5in wide x 90in tall if you like. That would work. Very large of course, but Bigger Is Better after all.

Do you mean why does the response of the modelled cabinets look rough? The models are 1/2 space -they don't acount for the load the room imposes on the pipe when it's correctly corner loaded. You will get some ripple, but anything over about 250Hz is massively over-estimated by these models. In reality, it's usually contained + / 4db in my experience.
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