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Old 26th January 2012, 03:29 AM   #4951
GM is online now GM  United States
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Originally Posted by mlwalla View Post
Thoughts?
Greets!

Thereís relative little extra boundary loading until itís nearing perpendicular, so you might want to consider flipping them to corner floor loaded.

GM
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Old 28th January 2012, 05:50 AM   #4952
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Default Alpair 10.2

Guys,

Would it be a good idea to put the 10.2 on the BIB ??

Albert
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Old 11th February 2012, 01:53 PM   #4953
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Youíre welcome!

Bummer, ĎFASTí and Ďsubí systems were the only way Iíve used pipe horns, but to date, no one has been willing to try one AFAIK. Oh well, maybe the answers will be of some help to others.

The standard BIB tuning is an octave lower [0.5*Fs] and I've tuned lower to get a pipe to the ceiling or to another corner when laid down to form an audio system platform, though of course these need to be corner loaded to provide at least some driver protection plus I mass loaded [vented] them a bit by using a vent area [Av] = driver effective piston area [Sd].

1, 2) A hornís fundamental is 1/4 WL, so 140"/155" = ~ 24/22 Hz pipe tuning [Fp]. The 0.707*Fs limit is mine for most reflex [ML] alignments until either the Fs gets low enough for room gain to help protect the driver and/or it has a high Qts, ergo high Qts drivers are ideal for TLs in general and pipe horns in particular.

FWIW, D.B. Keele's extended bass shelf [EBS] alignment specs a ~0.6579*Fs tuning with a 0.625 effective Qts.

3) Like any undersized, low tuned alignment, F3 rises, but if there's good room loading, this is mostly moot; otherwise, mass loading it solved the problem good enough for me and the folks I made them for.

The major dip is at the pipeís 3rd harmonic, which equates to ~ 1 WL [~ 2 octaves] away from Fp, i.e. a ~20 Hz Fp = ~ 80 Hz dip.

GM
Thanks for the detailed answer - it certainly clarifies things in my head somewhat.

I'm still planning a FAST system, but had chosen a different midbass driver (the Monacor SPH-210) with an Fs of 28Hz, so tuning below Fs was no longer a problem. The line was to be 170" for an Fp of ~20Hz.

That said, with your reply I'm now wondering whether to stay with the Fane: it does have a slightly higher Qts (0.38 rather than 0.24) and quite a bit more Xmax (5.5mm Vs 3.5mm) - along with a smaller Vas. It's cheaper and more efficient, too.

The Fane, tuned to Fp=31Hz=0.5*Fs, gives a box with a rounded-off footprint of 11.5" by 15.5", and a line of 110". IIRC, when extending the line you suggest keeping the same footprint - after all, more Vb can't hurt (again IIRC). Extend it out to 170" line to give an Fp of 20Hz and a box height of 7'2" (I have 9'9" ceilings here, so that's still 31" away), corner-load it, mass load with Av=Sd, and high-pass it at ~20Hz.

By the way, I'm planning to cross-over actively at 400Hz to a Fostex FF105WK in a ~2.5L sealed box. Conveniently, the 11.5" wide (external) cabinet that I got for either driver has a baffle step at about, oh, 400Hz - so any correction required can be done by altering the gain of the bass amp. I appreciate that the BiB is unlikely to need much, if any, BSC, but it's nice to have the option of such a simple correction, especially given those high ceilings.
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Old 12th February 2012, 01:52 AM   #4954
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Guys,

Would it be a good idea to put the 10.2 on the BIB ??

Albert
Don't know, but IIRC Markaudio has some concerns about some types of cab alignments, so best to check with them.

GM
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Old 12th February 2012, 02:04 AM   #4955
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Mark's concern is the potential of running his drivers too low too hard. If they are used sealed, then the box will prevent over excursion except when the user is being really stupid with the volume knob. However, I have a MLTL for the A10.2 that has f3@40 and F10@30. By 30Hz, the cabinet is unloading in a hurry and too aggressive bass boost or high volume will easily damage the cone. I would think that a BiB would cause the same concern. OB's pose even more danger, but most users will high pass the driver well above the danger zone.

Bob
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Old 12th February 2012, 02:24 AM   #4956
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Thanks for the detailed answer - it certainly clarifies things in my head somewhat.
You’re welcome!

Run them both in a reflex calculator tuned to whatever Fb you’d like, add some series resistance to match up Qes, Qts to see which one has the best power handling and/or if the higher price can be justified.

Right, there’s never too much horn acoustic efficiency, just a point of diminishing returns WRT size, but when going vertical it doesn’t seem that much bigger, quite the opposite as its visual aspect ratio narrows.

Hmm, IIRC, never did any where it was far away from the ceiling or corner if laying down, so no clue how this scenario will pan out, but ‘discretion being the better part of valor’, starting out high on the hi-pass seems a good plan if you’re going to use them for pipe organ symphonies, movies or similar.

When I was building them, the hi-pass was for TT ‘rumble’ as there was no commercially available music with any loud content below ~40 Hz, so a 20-27 Hz tuning was just for picking up the rolled off deep bass of a few recordings and the pipe horns added enough gain to add a bit of ‘fullness’ to make it sound more natural/life-like.

Anyway, looking forward to what you come up with and whether or not it meets your expectations.

GM
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Old 12th February 2012, 03:16 AM   #4957
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Quote:
Originally Posted by GM View Post
Don't know, but IIRC Markaudio has some concerns about some types of cab alignments, so best to check with them.

GM
GM,

Thanks. Will check accordingly.

Albert
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Old 12th February 2012, 03:19 AM   #4958
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Quote:
Originally Posted by Bob Brines View Post
Mark's concern is the potential of running his drivers too low too hard. If they are used sealed, then the box will prevent over excursion except when the user is being really stupid with the volume knob. However, I have a MLTL for the A10.2 that has f3@40 and F10@30. By 30Hz, the cabinet is unloading in a hurry and too aggressive bass boost or high volume will easily damage the cone. I would think that a BiB would cause the same concern. OB's pose even more danger, but most users will high pass the driver well above the danger zone.

Bob
Bob,

I have the drivers on my BIB originally for FE168EZ. It works wonderful and goes pretty low. I didn't try on highest volume yet and surely try this after the break in period.

Albert
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Old 13th February 2012, 08:24 PM   #4959
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BIB is a forgiving cabinet. I think you can just about pop any driver into it and it will work. The BIB will immediately reveal the character of the driver being used. For example, the Fostex 127e sounded delicate and sweet while the Dayton 5” full ranger sounded bold and full. These drivers have totally different specs but their personalities shined thru in BIBs… and to be honest, even tho the cabinet was designed to work with the 127e I prefer the Dayton in the same cab (which the BIB calculator configured a totally different set of dimensions). If anything, the Dayton is too bassy but nothing unpleasant or bloated… just a bit bassy. I’ve become curious about double mouthed horns lately. I’d imagine they’ll have their own set of pros and cons… and look forward to finding out.
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Old 14th February 2012, 03:03 AM   #4960
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Jeff,

I found the 10.2 sound even smoother and deeper in bass but still shining the mids and tops. I love it, my friend is going to take them back and build the same cab for them. I surely would buy a pair for this cab.

Albert
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