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[Matthew O'Sullivan]

Split up a JBL 4642 last year to create 2 approx. 10cuft units and fitted top holders for a pair of SX-300's (old school.....I know) Intend to build another pair similar for rear option and add 3 pairs of SX-300's (all double amp'd )for small shows split with DBX venu360 and others.
Wanted some thoughts on going to 12 cu instead of 10 for the second pair rather than just matching the existing pair.
JBL standard advice is 10 cu but the 12cu option goes lower with lower volume (see example advice like www.soundproject.com).
Anyone tried these options and compared the results ?
So I'll use them for PA but also will also happily plant them all in the home theatre. The new second pair design I'm considering is a slightly edited triangular design to fit them directly in corners.
I considered The added reinforcement for corner placement could render additional depth of the 12cu build unnecessary in a large room AV, but I wondered what effect that will have in  larger venue with corners I can take advantage of ?
Also what difference I'd see in actual performance between the two designs without corner placement for either pair.
Any thoughts gratefully accepted :-)
Cheers,
Matthew   

[Bob Leonard]

Read the rules and change you displayed name to your full real name and we'll be able to help.

[Mac Kerr]

Any thoughts gratefully accepted :-)
Cheers,
Matthew

Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac

[Matthew O'Sullivan]

all done - thanks

[Nick Enright]

all done - thanks

Note: The JBL 18" driver for it's time period, IE: each in their own technology, the 2240-68, are pretty much the best independent general subwoofer driver of their era.
(you might argue, but data proves.)

Here's my experience designing some subs with JBL 18's in the 224n series.

http://forums.prosoundweb.com/index.php/topic,135696.0.html

[Tim McCulloch]

Note: The JBL 18" driver for it's time period, IE: each in their own technology, the 2240-68, are pretty much the best independent general subwoofer driver of their era.
(you might argue, but data proves.)

Here's my experience designing some subs with JBL 18's in the 224n series.

http://forums.prosoundweb.com/index.php/topic,135696.0.html

So a little over 3 years on, how did it work out?

[Peter Morris]

Split up a JBL 4642 last year to create 2 approx. 10cuft units and fitted top holders for a pair of SX-300's (old school.....I know) Intend to build another pair similar for rear option and add 3 pairs of SX-300's (all double amp'd )for small shows split with DBX venu360 and others.
Wanted some thoughts on going to 12 cu instead of 10 for the second pair rather than just matching the existing pair.
JBL standard advice is 10 cu but the 12cu option goes lower with lower volume (see example advice like www.soundproject.com).
Anyone tried these options and compared the results ?
So I'll use them for PA but also will also happily plant them all in the home theatre. The new second pair design I'm considering is a slightly edited triangular design to fit them directly in corners.
I considered The added reinforcement for corner placement could render additional depth of the 12cu build unnecessary in a large room AV, but I wondered what effect that will have in  larger venue with corners I can take advantage of ?
Also what difference I'd see in actual performance between the two designs without corner placement for either pair.
Any thoughts gratefully accepted :-)
Cheers,
Matthew

The problem when you go bigger is that you lose efficiency and it becomes easier to reach Xmax, but you can go lower.

In this case if we set the max cone travel @ 9.5mm (a couple of mm greater than the rated Xmax) then the 10cu ft. box will take 600W, the 12 cu ft. box 500W and product 2 dB less output between 50Hz and 80Hz.

Red - 600W 12cu ft @ 36Hz- Xmax 10.5mm @ 50Hz
Yellow - 600W 10 cu ft @ 39Hz - Xmax 9.5mm @ 55Hz

Nominal Xmax 7.6mm

[Stephen Kirby]

Those JBL drivers were designed for a 60Hz kick drum thump.  Trying to make them play low will only cause them to bottom out at much lower levels.  Best to use them as intended, which is fine for band use.  You could have HT boxes tuned lower since the levels are lower, but I wouldn't take them out and run shows with them.

Also, while I love the sound of Sx300s they are 65 degree boxes.  Two of them are going to be pretty wide.  Not sure how you get 3 of them a side to behave together.

[Nick Enright]

So a little over 3 years on, how did it work out?

the 45" deep box worked very well, I finally got the hardware to properly measure the impedence curve and was able to get the driver motion fully controlled.

I used different sized 4x4 blocks to adjust the minor amounts of cabinet volume. That way each box was tuned to almost exactly the same. (Saw this in some HP700's, stole it.) Powered with an MX4000 and going from 32hz to 90hz the four subs did great up to around 200ppl. (in a 350 head room) another pair and they would have been fine. Some EQ was required due to the horn like effect of the slanted baffle board aiming at the port board.

When put up against 4 sb650s while not as loud, they went lower and sounded nicer doing it.

These drivers are old tech, and will only go very low when perfectly tuned for it... I ate 4 JBL OEM re-cones learning that. (and two more learning that the JBL rated power on DJ music is really all you ever want to send them in PEAK, so make sure your limiters are tight....)

Honestly I had to leave that venue over a serious lack of respect for what I did (full tech, electric, light, sound, and production management...) and these subs (that now sit doing nothing so an old 850 rig can be run badly) and the 6 belt pack, two panel mount station, Telex com system are the only things I wish I could have taken with me. (Spent 13 years building this indie venue...)

[Matthew O'Sullivan]

Setting 2 sx300's in 4 corners of hall for recorded music reproduction only. No live work for this setup. Might think of 2245's instead although i like the look of the td18+ from ae.

[Art Welter]

Those JBL drivers were designed for a 60Hz kick drum thump.  Trying to make them play low will only cause them to bottom out at much lower levels. 

Stephen,

The 2241 has an FS of 35 Hz, and VAS of 311.5 L (11 cubic feet). It is designed for big boxes that play low, not "for a 60Hz kick drum thump".  As you can see in Peter's simulation, around 60 Hz is where they will "bottom out" (exceed Xmax), unless you have put them in an undersized box tuned to 60 Hz.

Art

[Matthew O'Sullivan]

The 2241 is a venerable but high quality sub used in cinema based install subs by jbl for many years. See jblpro.com cinema sub range. Its not really pa based design and certainly not designed for a kick drum. The 2245 goes lower and 2242 goes louder 😊
I just happen to have 2 already that serve a dual role but are carefully managed and never pushed hard. They are not designed for pa, and they only do some dance show with recorded music work. But for that with sx300's they sound nice in a 300-400 seater. If they're eqd right

[Matthew O'Sullivan]

I was just hoping someone had tried the 2241 and 2245's in various sized boxes for themselves and had some comments 😊

[Nick Enright]

I was just hoping someone had tried the 2241 and 2245's in various sized boxes for themselves and had some comments 😊

I had success with the 2245 in an approximately 165L box.

you have to be exact in your tuning and power delivery and duty cycle.

they are good drivers I would go for a balanced box that gets to peak excursion around the same time the driver is soaking a good amount of power. Maybe 2x RMS Pink. At that point the tuning is pretty much set.

I found the best was a tuning at around 32Hz with the box small enough to get the resonance of the box fully controlled. Otherwise you'll get massive resonance at twice the tuning frequency.

[Matthew O'Sullivan]

Thanks nick ill start there in bassbox and play with that volume + tuning. Going to maybe do a trapezoid style to fit a corner. 

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