JBL 2245 Ideal enclosure

[Ralf]

and something interesting if you want to have a special frequence...(also 2245)

[hificanada]

I have been reading the enclosure guide for
the JBL 2245.

Does everyne follow this guide? It doesent
seem to go as low as i want it to go.

What is the ideal design if i want it to be down
to 14 - 16hz

maybe lower the FS of the driver in some way?

CORNER placemement

I had the same problem at first, built right to specs from the audio magazine in around the 1980's. I bump up the lower frequencies with a equalizer. I find the you got to get the equalizer just right, to much and I didn't get the lows I wanted , maybe the room had to much deflection or the amp did not have enought power. I used a coil, 16 quauge that I got free from the JBL rebuilder ten years later, when it needed to be reconed, it helped a bit, got rid of some more highs.
I heard if you put a cap across the speaker terminals helps to get a tighter sound. The size cap, I am still trying to find out.

[robertbartsch]

I have a few 18" sub bass systems - mostly in 10cf boxes.

Are you building the 14hz subs for your dog freinds?

I always thought the human ear can only hear frequences down to about 25hz. In addition, the music content in CDs and cinema DVDs doesn;t go below this anyway; right?

If I had a pair of dead 2245 baskets, I would see if you could recone them into 2240s since their sensativity is alot higher. some others here probably disagree, however.

[hificanada]

I have a few 18" sub bass systems - mostly in 10cf boxes.

Are you building the 14hz subs for your dog freinds?

I always thought the human ear can only hear frequences down to about 25hz. In addition, the music content in CDs and cinema DVDs doesn;t go below this anyway; right?

If I had a pair of dead 2245 baskets, I would see if you could recone them into 2240s since their sensativity is alot higher. some others here probably disagree, however.

Yes , 25hz is about right, but symphony's and especially the big Euroupean and U.S pipe organs on the 32ft stop , the lowest note on the 32ft stop is right on the farest left on the pedal, note C produces 15hz.
What they found with pipe organs already way back in the late 1600's is that even when one can not hear it, it still adds harmonics with the higher octive notes C, creating a more powerful sound. This worked so well that a few pipe organs and only a few even has the 64 ft stop.
The 2245H will do some of that also, one can feel the extreme lows that it can make, also adding to the higher octive notes in your system.
I don't recone, but want to learn that, I read that the 2245H has a special ring mounted on the voice coil to keep down problems with harmonics, that the large diaphram can make.
Added picture of the 64ft stop, the sleaves on the top of the pipe slides, if it is put up higher the lower the note will go , more internal Cubic ft, same with the sub enclosure's, al though once built , it can't be changed . So there is a place and reason for the extreme lows, one can't hear.

[robertbartsch]

I have a couple of 2245s that have been professionally reconed from 2240 cores. Also a single 2242 powered sub that is even better.

JBL OEM recone kits can only be purchased by authorized dealers, so don't expect to buy a kit and learn to recone for fun.

I thought many passive electronic crossovers and music mixes of CDs, movies etc. eliminated most signals below 25hz, in part, to minimize potential damage from ULF excursion.

Is this sub for sound reinforcement, HT or some other purpose?

[lgvenable]

I made my own, based on a 12 cu ft internal cabinet, two layers of box layer 1 = mdf, outside layer was walnut covered plywood. weighs a ton, 228 lbs; so I dont move it as much as slide it.

Thanks for those pads they sell to let things float on....

FYI it was designed to mimic the look of my L100T's thr navy grlll is not on

47" tall, 31 " wide 24" deep
the upper AB systems amps drvies it 60W biamped cintinuous......load with lots of driving bass.
my exovr is aDbx driverack 260 to conrtrol all inputs parametrically

[Doc Mark]

Good Morning,

Very nice job, Sir! I'll bet that sub can "do the deed", without even breathing hard!! Thanks for sharing it with us, and congrats on a job well done! Take care, and God Bless!

Every Good Wish,
Doc

[robertbartsch]

...looks a lot like one of my powered subs only this one is loaded with a 2242. My cab, however is designed so the woofer is firing down at the floor. The baffle is 10" above the floor.

I got the design idea from a cheapie contemporary powered Klip-horn sub.

This baby ROCKS the house foundation on my HT. It is powered with a 500 watt plate amp. When an earthquate, tornado, thunder storm, frieght train, or other impressive sound comes along in the movie you are tricked into believing it is real.

The dogs go NUTS!

[lgvenable]

Hey Doc good to hear from you:

Yes, and I used one of the 2245's from the same set of speakers as the one you got.

600W continuous creates earthshaking effects on movies. Combine it with this second sub I have, which is two 2240's again controlled parametrically using a dBX Driverack 260; and each speaker driven 600W by its own AB Systems 821 amp bridged mono; well you get my drift...

the 2245 sub does 25 Hz
the SR4719 w/2240H's is good for 30 Hz

So when 1 sub @ 600W is quite enough...do 3@600W continuous; and the effects from a movie are as good as anything I've ever heard at a high $$ venue.

Thank God for an understanding wife. She thinks I'm a bit of an audio nut anyway.

BTW the 4719 box was a find here in Evansville at a cost of $200 for the cabinet.

Larry

[hificanada]

Believe me, there is no other sub like it, I'll sure miss mine if it were gone, shakes the house with not to much effort, I power it with the Inter-M, 10.5 @ 350 watts RMS per channel. I built mine in 1983, probally one of the first in my area.

[JBL 4645]

I learned by Giskard, the jedi knight master of JBL reinforcement

Well JBL is also…Jedi Blaster Lightsabers.

Today I found some Informations about enclosures with 2245H. These are from JBL`s "Field Service Manual" from 198x. I got it from a local JBL-Dealer. Next time I will get it to scan it completely...

I'm surprised. That`s nearly the same result as I have calculated here:

Vented Box for 18"

Hey I like the idea of that tried drainage piping with bends and extended tubing attached to the my diy JBL 4645 a few years back. I wasn't sure if it worked because I didn't have decent way of seeing the frequency response on a recorded graph.

Any idea on the diameter of the tube I see 22" but what is the port diameter?

I have a few 18" sub bass systems - mostly in 10cf boxes.

Are you building the 14hz subs for your dog freinds?

I always thought the human ear can only hear frequences down to about 25hz. In addition, the music content in CDs and cinema DVDs doesn;t go below this anyway; right?

Well cats are limited to 40Hz to 90 KHz

[A Vanderkruk]

Sorry for late post to this thread , I didn't want to make one more 10cuft box. I thought of trying the 2245 in a horn again, this time rear loaded,I read on other threads that it was probably not a good choice to use the 2245 because of excursion limits. I went ahead anyway as i had these beauty's sitting in boxes since a fresh recone. Horn I made is for theater use first I thought it was going to be a sub,as my last front loaded corner horn was usable only up to 90hz, this thing is very different, it has a range 20hz to 1200hz so it make a two way system possible,easy even! I am in first testing stages, so far it seems very good, 100db of 20hz at 2.8volts RMS ,I don't know how that would compare to a 10cuft commended enclosure? Anyway i'm loving this thing the jBL is wonderful and i don't see any excursion problems at all, The drivers i bought were torn at the voice coils when I got them so my guess is they saw combat some where in the past. now they have the good life again.
pictures how do i post them

[Lee in Montreal]

Interesting

Do you have any diagram showing what's inside the horn? What brand of recone is that? How does it sound?

[A Vanderkruk]

Hi Lee, thanks for interst, I have a preliminay drawing that my freind Dieter made of it but it is not competely dimentioned , I could get him to finish the dimentions as they are now. It was one of the more simple cabinets I have made as all the interior panels are the same width so you just rip your plywood all at once. i made it to cut nicely from 5x5 sheets baltic birch 18 mm 13ply , no screws, all bisket joints (200 in all)
the matierials are 3 sheets 5x5 18 mm baltic birch AA-AA grade , each cabinet so 6 sheets for pair. The horn starts under the driver and scrolls around the compresion chamber. The interior throat section is made with my sand composit and requires a mould made of that. I didn't take any inside or building pic.
I will be building two more and I can take some inside shots then.
here is a preliminay drawing ,,, "Bentwood Goliath Horn" siesmic warrior
Oh and the drivers are new factory fresh cones , my neighbor was owner of the local JBL dealer so I got the real mccoy

[Lee in Montreal]

I am curious. How long is the horn path? 7, 8, 9 ft long? Throat to mouth.

BTW I am not persuaded the recone is a JBL one. The tinsels' length are the giveaway. They are too long. But hey, if it sounds fine, then be it... ;-)