31" jbl 2245?

[gasfan]

Just wondering what practical use a 31" 2245 with an Fs of 13hz would be? JBL never produced anything larger than 18". Why?

[JeffW]

JBL never produced anything larger than 18".

There's probably a clue in here....

[Lee in Montreal]

Say no to drugs ;-)

[gasfan]

There's probably a clue in here....

What? Too dangerous?:)

[gasfan]

Say no to drugs ;-)

That IS the drug, no?:D

[gasfan]

But seriously, I'd really like to know if something like that could be put to use, especially in a domestic space. EV made the Patrician.

[Mr. Widget]

But seriously, I'd really like to know if something like that could be put to use, especially in a domestic space. EV made the Patrician.Yes they did, but it really didn't perform as well as the numbers might suggest.

A cone that large becomes very hard to manage with a lot of breakup and high distortion. Smaller stiffer cones with greater Xmax have proven to be the better solution.



Widget

[badman]

A better solution is to use multiple smaller drivers rather than going to the extreme sizes. Some 18"s are excellent but most of the time, I'd take 2 12"s over an 18", both because of higher breakup frequencies, and because drivers in multiples give design flexibility. A pair of drivers can be implemented with force and distortion cancellation in a push-pull manifold setup (assuming pure sub duty as there is a low-pass component to manifolds), and that's a serious value-add in my experience.

Also, it's easier to maximize coil thermal handling when spread across multiple motors. In big motors, you have to add cooling/durability features to get thermal handling up where the simple act of spreading the heat sources out is just as good if not better.

None of this is to say that a 2245H cannot give superb performance, just that bigger isn't always better, and I tend to view 12/15" as the natural optimal sizes for subs based upon available technology.

Plus, multiple small subs spread around the room has modal performance advantages that cannot be ignored relative to single large subs.

[ivica]

A better solution is to use multiple smaller drivers rather than going to the extreme sizes. Some 18"s are excellent but most of the time, I'd take 2 12"s over an 18", both because of higher breakup frequencies, and because drivers in multiples give design flexibility. A pair of drivers can be implemented with force and distortion cancellation in a push-pull manifold setup (assuming pure sub duty as there is a low-pass component to manifolds), and that's a serious value-add in my experience.

Also, it's easier to maximize coil thermal handling when spread across multiple motors. In big motors, you have to add cooling/durability features to get thermal handling up where the simple act of spreading the heat sources out is just as good if not better.

None of this is to say that a 2245H cannot give superb performance, just that bigger isn't always better, and I tend to view 12/15" as the natural optimal sizes for subs based upon available technology.

Plus, multiple small subs spread around the room has modal performance advantages that cannot be ignored relative to single large subs.

Hi badman,
just for other info:
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf

(http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf)http://www.audioheritage.org/vbulletin/showthread.php?36677-subwoofer-placement&p=372157&viewfull=1#post372157

http://www.jblpro.com/ProductAttachments/JBL_5628_v7.pdf

regards
ivica

[gasfan]

A better solution is to use multiple smaller drivers rather than going to the extreme sizes. Some 18"s are excellent but most of the time, I'd take 2 12"s over an 18", both because of higher breakup frequencies, and because drivers in multiples give design flexibility. A pair of drivers can be implemented with force and distortion cancellation in a push-pull manifold setup (assuming pure sub duty as there is a low-pass component to manifolds), and that's a serious value-add in my experience.

Also, it's easier to maximize coil thermal handling when spread across multiple motors. In big motors, you have to add cooling/durability features to get thermal handling up where the simple act of spreading the heat sources out is just as good if not better.

None of this is to say that a 2245H cannot give superb performance, just that bigger isn't always better, and I tend to view 12/15" as the natural optimal sizes for subs based upon available technology.

Plus, multiple small subs spread around the room has modal performance advantages that cannot be ignored relative to single large subs.

I'm thinking about sheer dynamic impact...two 31" drivers facing you 15 ft. away in a 3 or 4 way speaker system.

[badman]

I'm thinking about sheer dynamic impact...two 31" drivers facing you 15 ft. away in a 3 or 4 way speaker system.

2 18"s per cab would have plenty of sheer dynamic impact though, without the design compromises required of a 31"

[gasfan]

2 18"s per cab would have plenty of sheer dynamic impact though, without the design compromises required of a 31"

But,..what if I just happen to have a pair of 31" drivers?:)

[badman]

But,..what if I just happen to have a pair of 31" drivers?:)

Then you might as well do it. Certainly they'll have some air-moving ability :)

[Ian Mackenzie]

Most of these large drivers are used in specialised enclosures often horn loaded they provide much high damping of the cone than your bass reflex tuning.

Another point is the VAS of a reasonable efficient 21 inch drive that termed extended bass is going to be very large and so will the box size. Ie double the 2245 box size 24 cu ft

Your home 21inch sub that can go low in a domestic size box is not efficient.

Therefore is the objective is more output and the expectation of going low multiple subs is a good idea.

2x 12= 1 15 (+3db sensitivity)
2x 15 = 1 18(+3db sensitivity)

[gasfan]

Then you might as well do it. Certainly they'll have some air-moving ability :)

Do what? I'm waiting for someone to tell me how to implement them. They are actually 2245s modified to 31". Still under construction but on their way. I came across a pair of nos cone kits with rotted surrounds. I also have a pair of 2245 baskets. I need some direction here. I've had parts cut on water jet to fix to the baskets and also have raw kevlar fabric on hand. No problem engineering them. I'm currently researching foam mold composition for surrounds. Also thinking to make them(surrounds) integral to the kevlar for stability. What I would like is for someone to help me implement them into a home environment. Can somebody here sim these? Nothing has changed except Fs will probably be around 12-15hz. Added mass will be like 50-60gr. More like 100

Hi Ian. I posted after you here.

[Ian Mackenzie]

You need to measure the revised TL parameters