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

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#5,421
More specific questions and comments regarding a FAST Bib

my current set of bib's are 8' tall and the largest box I could make out of two sheets of plywood for both speakers. I would like to keep those parameters if I can. Meaning I would prefer not to have to go larger.

On the woofer, I am not certain on parameters and placement on the line length for a smooth response. Since it is a woofer, I assume I have more flexibility in placement. And a lower Qts makes the box smaller. And I don't need to go much lower than 40hz for the Fs of the driver because of available line length. So an 8" or 10" with a low Qts and Fs around 40 is what I am thinking. Let me know where my thoughts are wrong please.

For the full range driver, how would I integrate it with the bib box? Sealed speaker within the bib? Or chamber front to back that can be stuffed to taste? Or left open back? I figure this is an option if I put the woofer on one side of the box and not the front.

I plan on driving the full range with tubes and the woofer with ss.

Just spitballing here.

What else do I need to be considering or doing research on?

Thanks
 
#5,422
If I read you right, you're thinking of a small FR driver for the top end in an existing pair of BIBs? You might be able to get by with something like a Fostex FF856WK in a 4" diameter ABS /PVC pipe, stuffed with dacron fibre, etc, . offset close to the larger driver, near the side wall and mirror imaged. Depending on total depth of BIB, you might not need the FR's enclosure to extend fully, and it could be sealed with the appropriate pipe end-cap fitting
 
#5,423
Chris,
Sorry for the confusion. I want to build a new bib. A FAST bib.

Lots of questions. So do I use the standard bib calculator and size the cabinet for the woofer? Maybe slightly bigger to account for the full range driver? Do I need to adjust the Zdriver dimension because it is a woofer?

Thanks
 
#5,426
ToddD said:
Chris,
Sorry for the confusion. I want to build a new bib. A FAST bib.

Lots of questions.
(1) So do I use the standard bib calculator and size the cabinet for the woofer?
(2) Maybe slightly bigger to account for the full range driver?
(3) Do I need to adjust the Zdriver dimension because it is a woofer?

Thanks
Click to expand...


Assuming you're looking for a single enclosure, rather than Godzilla's suggestion above, the resident experts on BIB-ology ( he and GM ) could pipe-in 😱 on those separate questions, but my intuition would be
1) Yes,
2) maybe,
3) probably not
 
#5,428
FAST BIB possible drivers?

So I have looked at quite a few drivers and plugged numbers into the BIB calculator (thanks Godzilla). These are the ones I am considering based on parameters, price, and preference (paper cone).

For the woofer:
Dayton Audio RS225P-4 8"
8" woofer, 4 ohm, 35-5500hz
Fs - 37hz
Vas - 1.84 ft3
Qts - 0.35

or

The 8ohm version
Dayton Audio RS225P-8 8"
30-7000Hz
Fs - 32.2Hz
Vas - 2.60ft3
Qts - 0.33

or

Eminence 8" paper cone Professional Woofer, 8 ohm
50-3500Hz
Fs - 37hz
Vas - 1.89ft3
Qts - 0.32


For the full range:
There are many to choose from but I am leaning toward the Fostex FE103En and using a sealed enclosure within the BIB. Is this a good choice for a sealed box? what size? 1-2 liter?
Fs - 83Hz
Vas - 0.21 ft3
Qts - 0.33

Crossover at 300-500Hz. Recommendation?

I have not heard any of these so I would appreciate feedback on my initial choices. Also, are Dayton and Eminence fairly accurate on their T/S numbers?
I am planning on sizing the BIB using the BIB calculator with the woofer parameters.


I am thinking about buying the drivers and installing them into existing boxes, satellites and woofers, while they break in and then get used to them before I build the BIB.

What say you?

thanks,
 
#5,429
I am using a "FAST" setup with B&C 10PS26 10 inch pro drivers in large BIBs and Faital Pro 3Fe20 mounted on small open baffle flanges on the side of the BIBs.

With a simple first order crossover at 1000 hz they sound marvellous. With active crossovers I can use a fourth order L/R xo at 400 Hz, but I prefer the simplicity of using one amp and a passive xo at the moment.

I want to test using a small line array of 12 to 16 Faital Pro 3FE22 per side in a small flange-mounted OB. This way I could cross them over at 200 Hz or so.

Cheers,
Johannes
 
#5,434
So do you continue to try different full range drivers or have you picked your favorite?
Click to expand...

I would love to try the PRV Audio 5MR450-NDY-4 in a short conical wave-guide/horn. I prefer pro-drivers like the PRV and Faital Pro over fullrange drivers from Fostex. There is nothing wrong with Fostex, but I prefer the price/performance ratio and the robust build quality of pro drivers. The 3FE22 compares very favourably to many other fullrange drivers I have heard. I consider the 3FE22 a real gem. Real nice sonic character. No typical "shout" or other nasty cone breakup related flaws. With the right crossover it is very clean and detailed, with a very nice treble. I can play ridiculously loud without any audible distortion or change of character. I have tested my BIB with a bridged QSC RMX1450 driven to clipping (900 watts peaks) without hearing anything bad from either the B&C 10PS26 or the Faital Pro 3FE22. It was painfully loud but very clean and with a very overwhelming powerful bass. When I paused the music I could hear my whole house twang like a piano dropped from several feet onto a hard concrete floor.

Mostly I play at more reasonable spl levels, and it sounds really really good with anything from Skinny Puppy to Ahmad Jamal, via Rammstein, Janice Joplin, Eva Cassidy to Buddy Guy and many more. These last weeks I have been playing with a 0,5 watt class A source-follower amp without any voltage-gain - directly from my M-Audio soundcard. 0,5 watts is enough to get my kids to complain that it is to loud since the bass is very "large" dynamic and effortless.

Cheers,
Johannes
 
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#5,435
Powerful pro drivers in large BIBs is very very addictive. There is an effortless easy natural and captivating quality to these high efficiency drivers in large BIBs. The music is very present and alive. You almost always stop listening and start moving to the music instead. It takes a considerable effort to sit still when playing your favourite music through large BIBs.

Cheers,
Johannes
 
#5,436
Hello Johannes, interesting. I used to have frontloaded bass horns with Eminence Kappa 12 drivers, and later used one in a Schmackshorn for 12" drivers. All those horns are gone, but I still have the drivers in storage... I built my current BIBs to extract to maximum range and powerhandling out of my arrays of mini fullrange drivers. Maybe time to take out the 12" drivers and build FAST BIBs.... 😀
 
#5,437
A BiB for Kappa12 gets kind of big. I'm approaching WAF by discussing colour schemes first, see where that gets me. 😉

Meanwhile, I've been making some measurements of my mini-arrays-BiBs. RoomEQwizard, Minidsp UMIK-1 USB mic, and I have a minidsp 2x4 in a box (balanced version) that is all by-passed for measurements. Green line is one BiB in a corner, 1 meter distance, frequency dependent windowing. The other line is measured at listening position, un-windowed, and boosted to compensate for distance (ball-park).

I have various other measurements, different positions of the BiB and different positions of the mic, I have various versions of DSP settings etc. Too soon to show the best/most informative set of graphs and the best DSP approach, but it's great fun. 😀

Not bad for a tiny driver with Fs = 190 Hz@
 

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#5,438
Don't study this graph too closely. They all look kind of different. 'm discovering which trends there are and where the biggest variations are.

The lacking high frequency at closer range is associated with the line array. It should disappear at bigger range and appears to do so. However, correcting it to measure more balanced at close range also sounds better at the listening location. However, bass is less at close range and more at the listening position, but boosting it to be balanced at close range doesn't sound good (quality OK, but too much). The midrange variations are different at every location I measure.

I also did some measurements away from boundaries and with tightly defined windowing, good reflection free data above about 300 Hz, but I realised I was getting mostly just front radiation from the array and some back wave. So what does that mean? I bet I'll be interpreting these various measurents with different windows and perhaps splicing different measurements together for different ranges.

Any golden advice here?
 
#5,439
I built a single BiB from scrap material. I was restricted to boards I had, so just drew up the largest folded pipehorn I could. Volume is roughly ok for the driver used, a Tangband W69-1042 woofer. This gave ~70Hz tuning frequency and possible in-room response of about 35-40Hz. It's pretty short, so instead of ceiling loading, it's on it's side now with the driver firing into a corner.

I was using two of these woofers in sealed boxes, Q 0.5, which combines well with my room. Bass didn't drop off at all! I really needed the dual sub setup to improve modes etc. I was expecting more trouble with room modes and a noticeably less extended bass (we watch violent movies and listen to large orchestral music, deep extension is very noticeable).

The "little" BiB with one driver sounds MUCH more dynamic and relaxed than two sealed subs with the same driver. Response does go down to about 35 Hz and is remarkably similar when measured at various positions. While I miss some known sound effects down low when I know about them, the overall sound suggests much lower response.

It's really very anonymous, blends to my "satelite" BiBs very well. I thought the tiny drivers were limiting dynamic capabilities, but it turns out it was the subs. The new sub-BiB changes performance dramatically.

I now desperately want to build a pair if 40hz BiBs. I drew up a pair of 12" FAST BiBs, but they were firmly vetoed. My first WAF incident! I'm looking into a pair of 8" FAST BiBs now. It's just an inch smaller here and there, not shorter. I don't really u derstand why she will allow those and not the others, but anyway... Not worth a fight. 🙂

Thanks Scott, GM, and of course Terry. I remember he was friendly and respected back then. Wonderful to see he leaves a lasting legacy.
 
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