Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 409 - diyAudio
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Old 3rd June 2008, 06:30 AM   #4081
zek is offline zek
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Join Date: Aug 2003
And what about to rotate BIB for 90* and put driver on one side like a monolith in 2001 A Space Odyssey ? Click the image to open in full size.
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Old 3rd June 2008, 12:50 PM   #4082
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Join Date: May 2005
Location: Buenos Aires
Originally posted by zek
And what about to rotate BIB for 90* and put driver on one side like a monolith in 2001 A Space Odyssey ? Click the image to open in full size.
There is not enough clearance to do that and get the driver at a reasonable height.
Besides that, there is more ripple in the monolith than in the slim profile + wing, that has the additional advantage to get back slim at will (WAF !).
Also, the ability to shape the frequency response is not to be disregarded.
All in all, IMO a wing is a better option, but as almost everything in life, it's a matter of tastes


EDIT: completed the post... it went away before it was finished.
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Old 3rd June 2008, 05:02 PM   #4083
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Location: Norcross, GA
Originally posted by zek
And what about to rotate BIB for 90* and put driver on one side like a monolith in 2001 A Space Odyssey ? Click the image to open in full size.
I actually did try that on some bibs I have, although I had the driver at the height specified by the iBiBk (inverted BIB, with the mouth pointed at floor). So the driver ended up being near the top, by the fold, on the side of the cabinet.

It didn't sound too good. I then actually flipped the cabinet again, so the speaker was on the side, but only about 8 inches or so from the floor. This actually didn't sound too bad, especially for background music. The highs were greatly rolled off, of course, but by tilting the cabinets up against the wall, the drivers pointed back up at the living area, and the radiation from the mouth bounced off the wall... it was not bad, for a while.

Then I read about the importance of the suprabaffle, and the huge difference in the T/S parameters actually measured for the Fe126e (versus manufacturer's specs). I performed surgery on my BIBs to shorten the line length, put the drivers back into their original position, and glued wings onto each side.

Of course, I glued the symmetrical wings on the day before reading the latest updates here about the better sims on asymmetrical wings, so I may be taking a saw to one of the wings someday.

But, I have to say, for right now, this is the best configuration - standard BIB, using the measured (by others) T/S parameters, and ample wings - mine increase the width from 6" to 13".
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Old 3rd June 2008, 06:38 PM   #4084
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Location: New York
>>> Godzilla, do you have the wings on both sides on the boxes or just one?

One side only. My BIBs are in the corners of the room. Maybe two inches from the side walls. One of the beautiful things about the wing is that it is totally stealth! I unfold it during listening and fold it back when not in use. I have still not constructed my final set of wings but think they will be 48" tall x 7" wide. Simple. Can that be measured?

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Old 5th June 2008, 03:31 PM   #4085
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Originally posted by GM
Not with any degree of accuracy. Yes, you can measure its specs. Anyway, tiny motor = high Qts, maybe as high as 2.5, so better IMO to try the MCWR8A, which has a motor size in line with its published T/S specs and add an inexpensive super tweeter if required.
Thanks GM! So I went to Q-Components, and they had the MCWR10A's on sale for cheaper than the 8A's, and I couldn't resist.

They sound nice and have similar specs. However, working out the numbers in the BIB worksheet, they call for HUGE cabinets:

29" deep
20" wide
94" tall

That won't fit standing up in my house :-)

Any suggestions for a good horn or TL or similar enclosure to get the most out of these lovely Canadian drivers? I've looked at the frugel-horn designs etc, but none of them seem to be made for anything like this driver...

Here are the specs:
Outside Dia...........................257 mm
Impedance...............................8 ohm
Power ........................................75 W
Freq. Resp ................37 Hz - 16 KHz
Magnet Wt ................................20 oz
Fs .............................................37 Hz
Qts ..............................................0.41
Qes .............................................0.48
Qms ............................................2.99
Vas ...................................115.5 litres
Voice Coil Dia .........................38 mm
SPL...........................................98 db
Depth ....................................117 mm

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Old 5th June 2008, 10:30 PM   #4086
GM is offline GM  United States
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You're welcome!

Well, to get the drivers down to ~ear height, the 'stock' ~48.78 Hz (Fp = 24.34 Hz) solves the height problem, but due to the medium high Qts and Vas we're still talking a ~27 ft^3 cab, fairly large even by my standards, so it's going to be impossible for these to 'be all they can be' in any reasonable size cab unless you want to buy two more to make them isobaric, assuming you consider a ~13.5 ft^3 cab 'reasonable' as I do.

Here's a modest size Alpha TL that when properly positioned to get some room to fill in the bottom octaves should be OK for most music:

L = 44.44"
W x D (CSA) = 214.985"^2

All dims inside (i.d.) and approximate. Place driver at the top front and the vent cutout = CSA at the bottom. Can be one big hole or spread out around the sides/rear. Make it as wide as practical to reduce/eliminate the need for any BSC. Stuff to 'taste'. Note the sim is 1.0 lb/ft^3 of polyfil.

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Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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Old 5th June 2008, 10:50 PM   #4087
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Location: Aotearoa
Default 208/T90A BIB with Different Amps

Just replying to Benjamin's post.

To be honest I haven't tried different amps with my 208/T90 BIBs but I am very happy with the T-Amp I use. This is the 41HZ Amp11 modified with separate 5v supply and better voltage regs in the 5v section, PIO input caps. This is very much like the red Wine Audio 70 monos but without battery PS (not convinced battery is better if your regs are good). Detail, space, power all wonderful, the AMP11/BIB setup cleary shows changes in other parts of the audio chain.

I would love to try a SET amp like the SEX and even considered buying one. But I am very much taken with the T-Amps, I have a Truepath kit waiting to be built.

And on the cap value. I started with 1uf PIO cap and no attenuation, slowly reducing to current value - comprises 2 Sprague PIO caps in // resulting value .54uF. I was surprised how high the x/over frequency was with this and still clearly hearing the T90 tweets.

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Old 7th June 2008, 01:13 AM   #4088
pebbles is offline pebbles  Australia
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Default T-amp

Hi, I've just purchased the KingRex T20 for my 168es BIBs and it performs really well. It's early days but it seems to add more body and colour to the sound with no apparent loss of dynamics even though replacing a very well regarded pre/power SS at about 10xprice. Remarkable really and without the recommended PSU. Regards, Andrew
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Old 7th June 2008, 04:52 AM   #4089
gnugear is offline gnugear  United States
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I just got one too (sans power supply) and it sounds fantastic!!

My Bottlehead 2a3 Paramount / Foreplay setup is better but not by much! I'm really impressed with the Kingrex stuff. I'm using it in my office setup but just brought it home and I'm currently listening over the weekend trhough my Lowther BIBs.
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Old 7th June 2008, 06:49 AM   #4090
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The T20 uses the Tripath TA2020, same as the 41HZ Amp6 kit - I have a couple of these and, yes they sound great with the 168 BIB - great combo. 6 watts is plenty!!

Amp11 is a step up tho. Really like to compare with a Bottlehead amp!

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