JBL 2269H - ported or passive? Need a little help... - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 13 Old 11-26-2017, 05:43 PM - Thread Starter
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JBL 2269H - ported or passive? Need a little help...

I picked up a 2269H to build a Sub18 clone go with my M2 clones (or close enoughs). The Sub18 specs http://www.jblpro.com/www/products/r...st/sub18#Specs give the external dimensions which works out to about 9 ft^3 gross (ignores driver, ports, bracing, etc) but no tuning specifics or port dimensions. Guessing from the photo ports are...4" maybe 6"...and let's guess 24Hz for tuning. Let's assume 2400 watts peak (Crown XTi4002 bridged mono)...the iTech 5000 isn't in the budget. Performance below 20Hz isn't a priority, I know this is the wrong driver to go ULF and below 24Hz looks challenging.

I used the 3" Precision Ports on the M2 clone so I figured a pair of the 4" or 6" should do the trick. Long story short...a pair of 4" gives a length of about 12" and the 6" goes about 30" which really doesn't fit in the box without elbows and consumes valuable cubic footage. Unfortunately the port velocity is very high for the 4" ports below 40Hz. As a practical matter, can you hear port noise when you are running >110 dB? I suspect I won't be running near peak power except to show off the system occasionally. Anyone know where to find a 5" diameter flared port?

Haven't done the math on slot ports because the first goal was to match the Sub18 look (if you can call it that). Come to think of it I could incorporate the slot port into a riser to get it up off the floor and eliminate the "problem" of the port consuming box volume (assuming I give up on round ports). Hmmmmm....

Next thought was to look at a passive radiator. I don't know much about them but Parts Express has an 18" model. Any help or advice on optimization would be appreciated. Runs out of excursion between 20 and 30 Hz depending on added mass. What does that sound like? Does it simply not produce the modelled SPL (sort of behaving like a sealed enclosure when Xmax is exceeded) or does it sound like frapping and/or thunking? It does look like the passive radiator does help keep the 2269 out of extreme over-excursion when driven hard below Fs/Fb.

I guess my question really come down to finding the solution that is most tolerant of being driven stupid loud at 20Hz while yielding acceptable SQ.

You guys are a great resource. Thanks!

Don
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post #2 of 13 Old 12-13-2017, 07:27 AM
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Wow Don-where were you able to find the 2269?
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post #3 of 13 Old 12-13-2017, 10:57 AM
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post #4 of 13 Old 12-13-2017, 09:23 PM
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I've been kind of curious too, so I grabbed the front perspective image from the site.





it looks pretty square, but isn't perfect.


cropped and imported into sketchup.


it indicates height is 27" including feet. I took 1/2" off for the feet. then put some measurements on the remaining scaled drawing.


the 18" driver measures 17.99" and that is with me eyeballing the cursor, so scale is probably good.


external port flare appears to be just shy of 7.5"


the white circles are 7.5" and 18" respectively.







I'm not sure if the ports are straight ports or not.


straight ports that fire into the rear wall at one port diameter or less will have some additional loading from the rear wall that will lower tuning by a little.
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post #5 of 13 Old 12-13-2017, 09:34 PM
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I'm calculating roughly 8.7 cubic feet internal before bracing and driver which probably comes down to around 8.33 or so.


if the vents are 5.5 diameter internal and 18" long, that would tune the cab to 26.25hz with no other adjustments in winisd.


if there is a little decline in tuning from the rear wall 24hz +/- seems like a good guess to me as well.


port velocity does get a little high with amp power that actually pushes the driver up towards xmax.


starting from scratch, I'd probably design the enclosure to be a little larger, so that it could accommodate a larger and longer port, and shoot for a little lower tune, perhaps 20-22hz, but then it wouldn't be a sub18.

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post #6 of 13 Old 12-13-2017, 10:00 PM
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Keeping within the spirit of the SUB18, but going bigger cab, bigger ports, lower tuning...







p.e. has the 6" ports for $40 ea. lol, but that would help keep the SUB18 spirit (in more ways than one). ;-)






the larger ports and lower tuning frequency reduce the air velocity.





as always, a reduction in cab tuning results in a reduction in output just above the tuning point.





excursion is a little over spec'd xmax, but that driver should be fine well past its xmax spec.


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Last edited by LTD02; 12-13-2017 at 10:18 PM.
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post #7 of 13 Old 12-14-2017, 12:22 AM
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I'm not sure if a single p.r. would be sufficient if that is the route that you choose.


lots of p.r.'s in use in the speaker world. obviously no chuffing with p.r.'s. I'm not sure what their impact might be on sound quality (if any). Probably little to no difference for a low tuned build.


output below tuning rolls off at 3rd order with p.r.s and 2nd order with ported (both need a highpass anyway).


this is what I'm getting for the SUB18 Plus ported (black) vs. p.r. (red).




with a pair of these p.r.'s: https://www.parts-express.com/dayton...iator--295-506




I'm not sure why p.r. has lower output.


p.r.'s don't get a lot of use because the space that they save generally isn't worth the premium that they cost.




and besides, with p.r.'s you don't get the same look. :-)


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post #8 of 13 Old 12-16-2017, 06:29 AM - Thread Starter
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Quote:
Originally Posted by Wrager View Post
Wow Don-where were you able to find the 2269?
Speaker Exchange, Tampa. http://reconingspeakers.com/
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post #9 of 13 Old 12-16-2017, 06:56 AM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post
Keeping within the spirit of the SUB18, but going bigger cab, bigger ports, lower tuning...
No doubt bigger is better but this is going in the living room so sticking closer to the original size is a good idea. My new CNC router is limited to about 31" x 32"...the table saw hasn't been kicked to the curb but I do like playing with the new toy. I also have some rosewood veneer I plan to use and need to verify the dimensions before I get too far into it.

I ordered the passive radiator but I'm going to hedge my bets by making the the rear baffle removable and working up a design for the external slot port/pedestal. Not much extra work to have the option of testing both configurations. Decisions...decisions...
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post #10 of 13 Old 12-17-2017, 07:23 PM
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Quote:
Originally Posted by mobeer4don View Post
No doubt bigger is better but this is going in the living room so sticking closer to the original size is a good idea. My new CNC router is limited to about 31" x 32"...the table saw hasn't been kicked to the curb but I do like playing with the new toy. I also have some rosewood veneer I plan to use and need to verify the dimensions before I get too far into it.

I ordered the passive radiator but I'm going to hedge my bets by making the the rear baffle removable and working up a design for the external slot port/pedestal. Not much extra work to have the option of testing both configurations. Decisions...decisions...

ah...sounds good. :-)


fwiw, xmech on the passive is 34mm. the tab in winisd "cone excursion (pr)" provides some sense of what that may look like. with a protective highpass, cone excursion is a few mm shy of xmech at 2.4kw in the model that I've got here and that is with a pair of pr's. side mounting the pr's (dual opposed) creates a balanced enclosure. sometimes the heavy weight of the mass loaded pr can cause the box to vibrate/move around.

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post #11 of 13 Old 12-20-2017, 07:21 PM - Thread Starter
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ah...sounds good. :-)


fwiw, xmech on the passive is 34mm. the tab in winisd "cone excursion (pr)" provides some sense of what that may look like. with a protective highpass, cone excursion is a few mm shy of xmech at 2.4kw in the model that I've got here and that is with a pair of pr's. side mounting the pr's (dual opposed) creates a balanced enclosure. sometimes the heavy weight of the mass loaded pr can cause the box to vibrate/move around.
Going with the maximum mass (1100g) keeps the PR excursion under control but results in a higher F3 (47 Hz) but response at 20 Hz is still solid. I'll play with the dimensions to see if I can make two fit on the rear.

Moving 1 kg mass +/- 25 mm at 20 hz could cause some serious vibration. I'll ask the wife to sit on the subwoofer during high-power testing to keep it from walking across the floor

Thank you for getting me to pay more attention to the modelling and design.

Don
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post #12 of 13 Old 12-21-2017, 12:09 AM
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your wife's entertainment notwithstanding, it might be best to "dual oppose" (one p.r. on each side) the p.r.'s so that their vibration will cancel.


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post #13 of 13 Old 12-21-2017, 09:07 AM
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Thanks...yikes! $850.. I just picked up a new B&C 21SW152-4 for about 1/2 of that ($484 on Amazon).
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