Bogen S86 in BIB Enclosure?

[squareguy]

Hey all,

I am opening a new workshop and I really need some advice. It is roughly 25'x50' with concrete floor and 17' ceiling. It is pretty echo'y but is getting better as more equipment is moved in. I am most interested in talk radio and background music. I want a single source for audio and I want to use a single Bogen S86 loudspeaker.

http://www.bogen.com/products/pdfs/conepdfs/S86_S10.pdf

My question is does anyone know if these are a decent match for a BIB enclosure? My idea is to use an inverted BIB to couple bass to the floor. It will not be positioned in a corner and it will be more centralized and several feet from a wall. Not sure of the Thiele-Small parameters or how crucial the dimensions must be. Can I just take the dimensions for a Pioneer BOFU and use that?

Thanks all.

 

[xrk971]

Can you get TS params for those drivers? If so, use the BIB calculator in the BIB thread and plug it in. Can't just use Pioneer BOFU - TS params can vary all over the place for different drivers and that impacts size of box tremendously. Maybe you should get drivers that have TS params - why do you want the Bogens? Don't they make camera tripods?

 

[squareguy]

Yeah, I figured it was a dumb idea. I'll just buy some cheap speakers from a thrift store.

 

[xrk971]

You still need drivers that have known TS params. Better off to get blowout drivers from Parts Express. Many options under $10 there that should sound very nice and certainly give you ability to design and build proper enclosure matched with the driver.

 

[Scottmoose]

I think he means he's going to buy some cheap speakers from a thrift store, not drive units.

 

[hitsware]

I don't remember Vas. I'd guess ~ 1 cu ft
Fs is ~ 110 Hz ...... Qts ~ 2.2
The S86 are very nice sounding (no whizzer)and good for OB
S810 (with whizzer) is also nice with a little more highs

 

[Greg B]

Bogen is an old and well known PA and commercial sound company. I used to have a Bogen PA amp. Bogen Products: Mixer Amps, Power Amps, Pro-Matrix, Mixers, MDT Speakers, Cone Speakers, Horn Speakers, Foreground Speakers, Music Sources, Microphones, Telephone Paging, Self-Amplified Systems, Office Communications, VOIP Gateways, Special Electroni

Anyhow, ceiling speakers typically have the sort of specs that should work well in this type of enclosure. It won't be optimum if you just wing it, but it would most likely sound at least OK. I'm pretty sure that is what TC did originally.

Alternatively, Bogen may well have T/S specs for those drivers. You could always ask.

 

[Scottmoose]

Actually Terry simply borrowed a Fostex cabinet for the FF125K & converted the dimensions from the original metric to the nearest rational imperial with 1in material. The cabinet has sufficient Vb for the 40-1354s higher Vas & Q to be largely swamped out.

If Q on the units in question is > 1, forget it.

 

[IG81]

So the monster BiB thread's "Fostex Craft Handbook" reference would then be where TC took this FF125K design from? What were the dimensions (roughly L, S0 and SL) of this original box?

I'm pretty happy with my FF125K's latest reflex enclosure, but always like to know more as I really like this driver.

IG

 

[Scottmoose]

They're in the book; I'll try to dig them out. But as I say, they're basically the same as what Terry used, he simply rationalised them to the nearest logical imperial dimensions with 1in build material.

I wouldn't recommend it for general use; it was presumably meant for low-level use in smaller spaces. If that applies of course & you don't mind pushing the driver (extremely) hard...

The 125K was never one of Fostex's more popular units. I think the miniscule rated Xmax put a lot of people off. But since most Fostex drivers have a very small rated Xmax & in the majority of cases are run well beyond that, I rather doubt it would have been an issue, relatively speaking.

 

[IG81]

I wasn't even sure there was an original standard-design BiB. I'll try to look it up.

FF125K's 0.15mm spec is verging on compression-driver territory. I never ran my pair too hard, but they behave nicely beyond this puny figure fortunately. I'm not scared to throw much of anything at them as I mostly listen near-field, they do desktop Pc duty quite well. I once made large masonite front-horns for them, that was pretty fun and highly-sensitive.

IG

 

[rka]

"use the BIB calculator in the BIB thread and plug it in"

Can you get TS params for those drivers? If so, use the BIB calculator in the BIB thread and plug it in. Can't just use Pioneer BOFU - TS params can vary all over the place for different drivers and that impacts size of box tremendously. Maybe you should get drivers that have TS params - why do you want the Bogens? Don't they make camera tripods?

use the BIB calculator in the BIB thread and plug it in

I went looking for the "BIB thread' but I can't find it (the "calculator" or the thread). Could you possibly be more specific as to the BIB calculator's location?

Thanks,
Roger

 

[GM]

I wonder why? https://www.google.com/search?q=BIB...57&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8

GM

 

[hitsware]

http://home.comcast.net/~mnjmiller/BIB.xls

 

[rka]

BIB calculator

I wonder why? https://www.google.com/search?q=BIB...57&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8

GM

Thanks GM for getting me close. I found a "copy" of the BIB calculator at http://www.diyaudio.com/forums/full-range/233720-just-found-bib-design.html
post #9 (for those of you that like specificity).

Roger

 

[GM]

You're welcome! I was surprised your search turned up empty since it's archived at several locations.

GM

 

[hitsware]

You're welcome! I was surprised your search turned up empty since it's archived at several locations.

GM

http://home.comcast.net/~mnjmiller/BIB.xls

Hey GM 🙂
Would you check the above to see if
anything was messed up in my iteration ?

 

[GM]

I am opening a new workshop and I really need some advice. It is roughly 25'x50' with concrete floor and 17' ceiling.

My question is does anyone know if these are a decent match for a BIB enclosure? My idea is to use an inverted BIB to couple bass to the floor.

Can I just take the dimensions for a Pioneer BOFU and use that?

I don't remember Vas. I'd guess ~ 1 cu ft
Fs is ~ 110 Hz ...... Qts ~ 2.2

Very close to the mean for this type of 8” IME, with the Bogens I had measuring very close to the old RS 40-1271, 1272 series, so for cab designing, a good ‘worst case’ set of specs to ensure a large enough cab to have some tuning flexibility:

83 Hz Fs
32.85 L/ 1.16 ft^3 Vas
2.446 Qts

This equates to a nearly 71 ft^3 BIB!, so not really practical per se, especially when used inverted with a very high Fs driver.

There were several posted B20 BIB alignments, so choosing the 96” one to fit it on a 4x8 sheet of plywood, it’s ~24 ft^3 net, so while it’s considerably smaller, it’s probably too under-damped without being stuffed like a typical TL, which will of course negate much of its LF gain.

These types of PA drivers all spec similar enough that a ~10 ft^3 sealed cab is close enough to being an IB for an 8”, so plenty big enough for a stuffed ‘to taste’ TL, which in turn will allow us to de-rate it to ~8 ft^3 for a well stuffed one [simmed = 1 lb/ft^3 of polyfil].

With a 94.5” i.d. height, this equates to a ~146.28”^2 CSA with the amount of TL damping varying based on driver offset [distance from closed end to driver centerline].

With a 17 ft ceiling, the driver ideally needs to be at some odd harmonic of it and unfolded, the driver offset at 1/3 lines up close enough to 17/3 and gets it up off the floor high enough for some shops.

Moving it to the closed end improves damping of course, but may not put it close enough to a 17/5 harmonic, though only one way to know for sure.

GM

1st sim: B20 BIB, no stuffing
2nd sim: B20 BIB, with stuffing
3rd sim: offset driver TL
4th sim: end loaded driver TL

 

[GM]

http://home.comcast.net/~mnjmiller/BIB.xls

Hey GM 🙂
Would you check the above to see if
anything was messed up in my iteration ?

Greets!

It's fine as far as it goes, but you didn't use the formulas to make it rectangular to minimize screwing up the expansion through the fold. Not sure if it would be audible though.

GM

 

[Godzilla]

You can download the BIB Calculator from this link:

https://sites.google.com/site/speakerprojects/enclosures/bib

Zilla