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Dave71



Joined: 21/04/05
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Loc: Lat: 54:24:38N Lon: 1:43:30W
the merits/pitfalls of small but many - bass bin related
      #1027033 - 04/01/13 09:52 PM
A hypothetical question really.

As said in the title would there be any merit in using two 2x8" bass bins over a single 1 x 15" Obviously a 2 x 2x8 config would give to the total surface area of approx 200 inches where as the 1 x 15 would be 176"

Looking at the spec of 2 active bass bins
2 x 2x8" - FBT Vertus sub CLA 208 - @ 600W 125/129dB SPL each
1 x 15" - FBT Promaxx 15's - 1200w 136dB Spl

Now i've heard a complete FBT Vertus CLA in action and was impressed at the sound quality but it didn't really have any umph.

Obviously the like of Bose have managed big sounds from small drivers. Just wanted to learn a bit more on the subject.

Cheers

--------------------
No more kebabs


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Sam Spoons
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Joined: 23/01/03
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Loc: Manchester UK
Re: the merits/pitfalls of small but many - bass bin related new [Re: Dave71]
      #1027037 - 04/01/13 10:36 PM
Great question Dave. My gut feeling would be that bigger drivers produce bigger bass.... Then my bass player/mate bought a 4x8 Ashdown Superfly cab to go with his Superfly head..... Definitely no shortage of bottom end there... However, we all know that bottom end can be an illusion (e.g. cleverly produced tracks which generate lots of first order harmonics to create a feel of good bass even on domestic systems which roll off at 75-80 Hz. I'd guess if you have several drivers in one cab working in phase then they will behave like a single larger driver to a point but, being small drivers, they may have a reduced cone excursion compared to larger drivers so will move less air despite more cone area. If I ever get the chance to compare one 18" bin to four or five 8" home cinema subs (pretty unlikely) I'll let you know

Looking simply at the specs, the 15 giving 136 dBs is much louder than the 2x8 at 126dBs and assuming you then mean that two 2x8's produce 129dBs they are still nowhere near as loud as the single 15".

Edited by Sam Spoons (04/01/13 10:53 PM)


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Dave71



Joined: 21/04/05
Posts: 645
Loc: Lat: 54:24:38N Lon: 1:43:30W
Re: the merits/pitfalls of small but many - bass bin related new [Re: Dave71]
      #1027040 - 04/01/13 11:33 PM
not sure what the combined spl of 2 of the 2x8 subs stacked together would be, just copied the spec of a site. I think the Max spl of each unit is 129dB (or so they claim).

would be very interesting to hear an AB comparison. Obviously the smaller ones can be used on their own for small functions and doubled up for bigger events, if it is as good.

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No more kebabs


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Sam Spoons
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Joined: 23/01/03
Posts: 1523
Loc: Manchester UK
Re: the merits/pitfalls of small but many - bass bin related new [Re: Dave71]
      #1027055 - 05/01/13 10:04 AM
If I've got it right then if one sub can give 129 dBs, two will give 6 dBs more or 135 dBs so nearly as loud as the Promaxx. The dB numbers are continuous/peak according to the FBT manuals, they don't mention the dominant frequency at max SPL. The published frequency response for the Vertus 2x8 sub is 50-150 Hz (-6dB) and has a big peak at 100Hz the Promaxx 15 has a response of 38-120Hz with the peak at around 70Hz (though the Promaxx graph seem to contradict the lower -6dB point).

So, the resonant frequency of the Promaxx appears to be 30 Hz lower than the Vertus which suggests the Promaxx will sound fatter (phatter?) than the Vertus. Phew, got there in the end........ However, as always the only way to be sure is to give them listen (like wot you said guv)

http://www.fbt.it/ENG/PAE/PRODOTTI/LINE-ARRAY/Vertus/CLA208Sa/VERTUS-CLA.p df
http://www.fbt.it/ENG/PAE/DOWNLOADS/Datasheets/ProMaxX-15SA.pdf


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