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View Full Version : JBL SR4719X - 2241H Popping Noise. Ideas?



theriam
02-22-2014, 11:33 AM
I have a pair of SR4719X that have been barely used. One of the 2241H 18" drivers seems to "pop" or unload when driven fairly hard. This happens only on the very lowest frequencies (40 to 30 Hz) found in much of todays Rap music.

I am running a dbx PA+ processor with the low pass crossover set to roll off at 30 Hz at 24 db. Each cabinet is powered by a Crown MacroTech 2400 bridged mono and the cabinets are wired in parallel - 4 ohms each.

Any ideas to try or things to look at? Do I just have a bad driver?

Would switching to a MA 5000 running in stereo be a better choice for subs than the bridged MA 2400's?

Thanks in advance for the help.

Mike

wpod
02-22-2014, 01:46 PM
Although it should be remarkably obvious, don't listen to rap music! (Sorry, I couldn't resist):D Seriously though, I'd be suspect of that 2241H driver. Do you have the means to remove it and give it a low frequency sweep? If you don't have a signal generator, you can use your computer and download this:http://www.nch.com.au/tonegen/ Good Luck, hope you find the offending culprit. Paul

theriam
02-22-2014, 02:27 PM
Hi Paul,

Thanks for jumping in. Gotta play what the crowd wants, no matter what I like! :bouncy:

I have the driver identified. When I test it in the cabinet and sweep from 100 to 30 Hz, one of two 18" in this cabinet "unloads", as if it is in free air, maxing out its excursion, causing a popping noise.

These subs only have 2 summers of light duty weekend use. I find it odd that one driver acts that way only under load. Sounds like a driver defect?

Any thoughts out there on the Crown MA 5000 in stereo vs (2) MA 2400 bridged for sub use?

grumpy
02-22-2014, 05:22 PM
Pro shop might be able to tell if it's something like a failed spider...

Lee in Montreal
02-22-2014, 06:30 PM
Remove the woofer and check it with a sweep test. You will see if the spider has unglued.

martin2395
02-23-2014, 08:29 AM
I also suggest to check the wires that go to the voice coil.

Mike Caldwell
02-24-2014, 05:28 PM
What does the speaker suspension feel like. A friend of mine had 2241 that would pop and fart at the slightest hint of driving it with any power. The suspension was so worn out if you held the speaker up side down the cone would sag down 3/4 of inch. Over powering it for years in a poorly tuned box took it's toll on it.

subwoof
02-24-2014, 06:47 PM
get 2X the number of cabinets for that amount of power - and/or change to the 2242.

Cone area is important for sufficient low end and you should put all the cabinets side by side - forget the "stereo' stacks method.

the 2241's suspension just isn't durable enough and I will second the failed spider glue theory...

Have seen many many blown that way..and catch fire.

sub

Mike Caldwell
02-25-2014, 05:42 AM
If the spider glued failed and it is only in one area leaving the the voice coil still centered, with the proper glue and a little finesse you can glue back down.

As for cabinet powering, a bridged MA2400 into four ohms is basically the same power as a MA5000 stereo is into four ohms. That said many people would rather run a larger amp in stereo than bridging a smaller amp. When bridged each channel of the amp sees half of the total load impedance, in your case that would be around two ohms or possibly less depending on the frequency. Over all less stress on the larger stereo amp the pushing a smaller bridged amp.


Are you using the sub harmonic synth function in the Drive Rack, if so I would turn it off.

As "Subwoof" said the 2241 while a good sounding 18 just does not have the durability to hang with todays high powered usage that newer designed 18's do.

Fort Knox
02-26-2014, 05:14 AM
If the spider glued failed and it is only in one area leaving the the voice coil still centered, with the proper glue and a little finesse you can glue back down.



As "Subwoof" said the 2241 while a good sounding 18 just does not have the durability to hang with todays high powered usage that newer designed 18's do.

I throw away the supplied glue ..w/kits..
and ..as for durability..I think ..the 2241 is like a C130, it's already combat proven...

Bobecca
02-26-2014, 07:00 AM
Hi

I am using a MA5000i powering a two subs 4641 in mono in, dual out. Limiter set to 600Watts and peak voltage to 138Volts and is a very great combination for my setup. No problem or issues with durability:)

Fort Knox
02-27-2014, 05:35 AM
Hi

I am using a MA5000i powering a two subs 4641 in mono in, dual out. Limiter set to 600Watts and peak voltage to 138Volts and is a very great combination for my setup. No problem or issues with durability:)

It's vary tricky to project bass evenly in any given venue..that's one reason the sound man unwittingly may overdrive the bass signals..... Large wing panels or rear wall projected bass.. helps holds down the damage ..to the 2241 w/better efficiency and hence durability...