JBL 2245H 18" Bass unit in a "Transmission line" enclosure

This would make for a very large cabinet which would not be an issue for me, but I would be very interested to learn if anyone has built one based on the JBL 2245H 18" Bass unit or a big TL using a similar 18" driver.

PMC use the 15" Volt (RV3363) in the large BB5 system, which has an fs of around 29Hz. The line length is effectively 4m or 13' according to PMC the actual physical length is a bit shorter at just under 3m. Using 1/4 wave criteria works out at approx 2.9m, so close.

I did consider the bigger Volt RV4564 which has a resonance of approx 26Hz which would offer greater performance than the BB5. Based on the BB5 specs 1/4 wave comes out at 3.3m (PMC effective length = 4.6m)

Anyway I am interested to learn if anyone has used the 2245H? I will model with it as a matter of interest.

I happen to have a pair of 2245H drivers doing very little, so propose a stereo pair of enclosures.
 
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GM

Member
Joined 2003
Not a TL, but a vented [ML] TL for an early high end HT and yes, it was huge by most folk's standards. Don't remember dimensions other than it was my standard 58.5" i.d. line length and folded in half to be more cubic to fit under the stage, i.e. looked like a big BR laid on its side, but deep.

For a TL, tuning to Fs would be near IB large [1+ kL net], i.e. ideally be a false wall cab or similar, though a TQWT is 'only' ~488 L net.

GM
 
The JBL 2245H has a Qt = 0.27 as it is slightly lower than ideal to some, they recommend tuning approx 5Hz above resonance, to say 25Hz Using a TL would result in an enormous enclosure.

I agree with GM and if the 2245H is tuned to resonance, the enclosure would be at least as large as Vas which is 820 litres; anyway this would be a big enclosure. Guesstimate ~ 6' x 3.5' x 2'
 
I built one for Peavey Lowrider 18

I built one for Peavey Lowrider 18. Should be similar for JBL. Mine is a tapped Quarter Wave Pipe (similar to Tranflex design). 1220mm x 570mm x 520.7mm. 100db sen. At Xmax it puts out 126db down to 40hz. Designed in Hornresp. Super easy build, one fold. Real building shaker. I'm building a second one.
 
Looks like a JBL 2245H in a 311.28 Litre, single fold tapped- QWP would look pretty good down to 40hz.Duct and opening would be 1297 sq. cm. Line length would be 94.488". If you tune to just under 30hz it becomes a 370 Litre, you give up -3db. and 145.7" long duct. Yes that's huge. I would settle at 40hz.
 
If you go with an MLTL design, you can get that 30 Hz... :)

(note - this will likely have to be fine-tuned a bit, but it's a start)

EDIT - it will obviously have to be tweaked, because the box width is 18" and the driver's width is 18.3". That's not going to work, LOL. But it should give an idea of what's possible....
 

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Looking at the excel sheet lower part of the horn (the last bend/port to front) Would it benefit to do a 'venturi' style port like the DSL-CS30?

It can be done, but it will not be possible to model it in Hornresp, at least with that particular type of fold.

I've been looking at this alternative fold as an option, and it is possible to model this in HornResp (if one makes a few assumptions about the S1 section), but the problem here might be that it may not be possible to physically locate the driver at the optimum position along the QWR's path.
 

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