alteclipsch
Super Member
Someone near me built a pair of these based on an article on Lansing Heritage. Anyone know what it would be like?
JBL 2245H 13 cu ft Subwoofer
- Thread starter alteclipsch
- Start date
Its a bit different than the traditional B460 clone
http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm
http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm
donprice
Wound up workin' at a gas station....
As noted in the article Heather linked, 12 cubic feet gets you a relatively flat response without using EQ like the 8 cubic ft B460 requires. I built one for my brother and it is thunderous on very little power. But it is big. I have the B460 at home and it is a keeper.
Got a good friend with a B460 and 250tis, and another with 4 2245 subs stacked in his closet ...
I'd sure have a look if the price is good!
There is no substitute for cubic volume - if you can fit it in your space!
I'd sure have a look if the price is good!
Sure - that's why I searched, found, and linked to the Lansing article ...
There is no substitute for cubic volume - if you can fit it in your space!
Last edited:
Don, Have you tried these with your M2 DIY's?
audiomagnate
Addicted Member
I use 2245 in an infinite baffle setup. It's the best sounding sub I've ever owned by a long shot. When it comes to subs, bigger is always better.
donprice
Wound up workin' at a gas station....
Of course. I only have room for one monster system
The same one the wife watches General Hospital on
This reminds me of something I built in the early days of Audiokarma- a 27" cube, with a 2245 and a custom-built 18" passive radiator, with a 500w plate amp. About 9 cubic feet, internal volume.
With the parametric EQ on the plate amp, set for about 7dB of boost at 20Hz, and a PR tuning of just below 20Hz, the f3 was just about 20Hz. And it would do it LOUD. As in moving a 6' square plate glass window, in and out about 1/4", in the NEXT ROOM OVER from where I had the sub set up. We never specifically measured it for peak SPL, but that single sub should be able to hit 120 dB. That's bass...
Regards,
Gordon.
With the parametric EQ on the plate amp, set for about 7dB of boost at 20Hz, and a PR tuning of just below 20Hz, the f3 was just about 20Hz. And it would do it LOUD. As in moving a 6' square plate glass window, in and out about 1/4", in the NEXT ROOM OVER from where I had the sub set up. We never specifically measured it for peak SPL, but that single sub should be able to hit 120 dB. That's bass...
Regards,
Gordon.
audiomagnate
Addicted Member
Gordon, what did you use for a passive radiator? +7dB at 20 seems like it would be pushing a single 2245's Xmax limit, unless maybe you rolled it off below 20. I just might build one and get my fireplace back!
Last edited:
I built the passive radiator. If I had to do it again, I'd use something like a replacement cone for a PAS LX2800- giant rubber surround. I built it into a derelict 18" woofer frame.
The amp had a subsonic filter- I set it at 16Hz.
The boost actually was at about 22Hz, IIRC. And, the PR did a magnificent job of limiting woofer cone excursion at around 20Hz- better than a port, IME (much lower losses than a port tube). The 2245 cone would actually move more at 30Hz, than at 20Hz. The PR, OTOH, would be just, as the car audio guys like to say, "wanging away" at about an INCH or more of excursion, at high output levels near 20Hz...
Regards,
Gordon.
Superampman
AK Member
What are your thoughts on isobaric 2245 subs in parallel? I'm thinking 6cu. ft. per cab. Simple cone to magnet with the internal driver mounted to the front via 18" concrete form tube with long bolts. You'd never know it was isobaric to look at it. Eliminate even order harmonics with tighter overall definition.
I have a pair of 2245H 18" drivers in 18 cu. Ft. vented enclosures of my own design. I was always quite pleased with them until I replaced them with a pair of Bill Fitzmaurice designed HT Tuba 1/8th wave folded corner horns using 15" drivers. The corner horns are also 18 cu. Ft. The JBL subs haven't been played since 2004 so I imagine they have bad foam surrounds. When I was using the JBL 18s in my system I loved the thunderous bass power down into the low 20s. The 2245H is a truly excellent driver, but the corner horns are a better match to the mids and highs in my 3 way all horn loaded triamplified system.
Superampman
AK Member
I think we'd all like to see a pic of those
elitopus
Addicted Member
Could one use some cheap car subs as PR's? It wouldn't be that hard to pop the magnets off.
I know they usually have some pretty big surrounds.
How about two 12" PR's instead of the 18"?
You need a really high excursion and a low resonance (~15Hz) for a PR for this.
You'd also need to fabricate a way to add weight to whatever you use.
I don't remember how heavy the whole cone assembly wound up- and that's one problem with using an existing woofer- you don't know how much weight you're starting with, either. But, if you can find a woofer that states moving mass (in either grams or ounces), you can go from that, and just add what you need.
I briefly used the calculator here: http://www.mh-audio.nl/PassiveRadiator.asp
For a "normal" 18" passive radiator (effective moving cone diameter of 16 inches), in a 9 cubic foot enclosure tuned to 20Hz, you'd need about 515 grams total moving mass (add whatever to the existing Mms/moving mass to get 515 grams).
For the same 18" radiator in a 13 cubic foot enclosure tuned to 20Hz, you'd need about 345 grams total moving mass.
More accurate results can be had, if you know the true Sd (effective diaphragm area) of the driver you're making into the PR. You can get the effective diaphragm diameter from the calculators on that site, then punch that into the tuning calculator to figure out the weight you need.
Regards,
Gordon.
You'd also need to fabricate a way to add weight to whatever you use.
I don't remember how heavy the whole cone assembly wound up- and that's one problem with using an existing woofer- you don't know how much weight you're starting with, either. But, if you can find a woofer that states moving mass (in either grams or ounces), you can go from that, and just add what you need.
I briefly used the calculator here: http://www.mh-audio.nl/PassiveRadiator.asp
For a "normal" 18" passive radiator (effective moving cone diameter of 16 inches), in a 9 cubic foot enclosure tuned to 20Hz, you'd need about 515 grams total moving mass (add whatever to the existing Mms/moving mass to get 515 grams).
For the same 18" radiator in a 13 cubic foot enclosure tuned to 20Hz, you'd need about 345 grams total moving mass.
More accurate results can be had, if you know the true Sd (effective diaphragm area) of the driver you're making into the PR. You can get the effective diaphragm diameter from the calculators on that site, then punch that into the tuning calculator to figure out the weight you need.
Regards,
Gordon.
elitopus
Addicted Member
Ok thanks Gordon.
It makes sense that it would be easier making the PR from a recone kit then. At least the specs for them are more readily available than lets say a cheap 15" woofer.
Other options I see are pre-made PR's on ebay. I could probably get the moving assembly weight on those too.
This is something I am going to seriously consider. Since I already have the JBL drivers, and already have cabs around the right size.
It makes sense that it would be easier making the PR from a recone kit then. At least the specs for them are more readily available than lets say a cheap 15" woofer.
Other options I see are pre-made PR's on ebay. I could probably get the moving assembly weight on those too.
This is something I am going to seriously consider. Since I already have the JBL drivers, and already have cabs around the right size.
