2x18" with JBL 2243. Need design advise - Page 2 - diyAudio
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Old 20th January 2013, 05:59 PM   #11
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Quote:
Originally Posted by Joppepoppo View Post
I've seen other recommendations for this driver to be used in JBL S1S-EX boxes that originally used JBL 2242. The JBL 2242 share the same motor but have a lighter cone, raising the Fs to 35Hz and increasing the sensitivity.

If I've done the calculations right, that box is about 260l. Is that the minimum size I could expect? Simulations in WinISD seem nice with 240l tuned to around 30Hz.
These are they, on fig.1 a 2242 driver in a small box: JBL 2242H, VB = 97.4 L, FB = 37.6 Hz
(F3=57Hz, F6=44Hz, F12=32Hz, F24=20Hz)

On fig.2 the 18" 2243 in a small box: JBL 2243H, VB = 45.7 L, FB = 45.8 Hz
(F3=75Hz, F6=58Hz, F12=42Hz, F24=25Hz)

Note: they are just example simulations always having in mind that functions/alignments objectives for both passive filtering and active amplification/DSP (in this case) are rather different.
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Old 20th January 2013, 06:20 PM   #12
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In a similarly designed box (170 L), notice that this his only a comparison and not an optimized enclosure/alignment for the designated driver, we have for the same two drivers JBL 2242 vs. JBL 2243,
(drivers are similar in SPL calculated at 95.4(1)/95.5(2) dB/2.83V/m)

Fig.3 JBL 2242H, VB = 170.0 L, FB = 39.5 Hz freq. output
Fig.4 JBL 2243H, VB = 170.0 L, FB = 32.0 Hz freq. output

Also notice the high attenuation >5dB of the low frequencies, with alignments close to 30Hz tunning, in the second case.
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Old 20th January 2013, 06:28 PM   #13
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Default JBL 2242 vs. JBL 2243

Quote:
(JBL 2243 and...) JBL 2242 share the same motor but have a lighter cone, raising the Fs to 35Hz and increasing the sensitivity.
That is the case, increased sensitivity. If you look at the graphs the 2243 is 5dB's down at lower frequencies.
But if you look closely (fig.3) for the 2242 at 30Hz you have attenuat. 11dB's and for (fig.4) the 2243@30Hz (same frequency) you have -8dB's. I don't know if that is what you are expressing in your comment?!
Fig.5, fig.6 for the cone displacement or excursion, showing the maximum excursion in the ~30's for the 2242 and in the -20's for the 2243, this one having lower excursion (at 30Hz 11.5mm for 2242 and 5.0mm< for 2243) for a similar volume designed (170L) box and considering different FB as above.

Fig.5 JBL 2242H, VB = 170.0 L, FB = 39.5 Hz excursion
Fig.6 JBL 2243H, VB = 170.0 L, FB = 32.0 Hz excursion

Last edited by Inductor; 20th January 2013 at 06:57 PM. Reason: max. excursion
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Old 20th January 2013, 08:19 PM   #14
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What trade-off do you get with large boxes? My Win ISD simulations show that the Group Delay times increases with larger boxes. How important is group delay, do I need to take it into consideration? I want fast, dry bass...

I'll need 2 or 3 bass ports per box. Anyone has a source with nice looking ones?

And I'll need to recess the drivers and put some grill cloth in front of them. I'll hopefully be a daddy soon, and I'd hate to get curious childrens fingers putting holes in the dust cap

I must scan the internet to try and find some pictures. Still haven't got a clue what the boxes should look like...

Thanks for the router tip. Time to go shopping
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Old 20th January 2013, 08:41 PM   #15
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JBL 2243H is also good in a horn.
I don't know what kind of horn is applicable i.e. software, calculations, etc.
I am just giving an example. This was posted by another member for the P Audio SD18.
Sub Plans - X1 - Speakerplans.com
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Old 22nd January 2013, 02:11 AM   #16
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I have some of the JBL high power cinema array subs that use two each 2242's per box. The exterior dimensions are 24" deep by 30" wide and 50" tall. They are tuned to 25hz with a common rectangular port in between. Here's a link with pics.

JBL :: Product

Put a 2kW amp on these and look out!
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