JBL 2242H/4645C rattling - anyone ever had this?

[Silas]

I've got a JBL 4645C that just started to rattle whenever it plays low. I currently don't have any protection on it (i.e., high pass at 20Hz), though I have a MiniDSP in the mail to do just that as well as provide some low end boost around 25Hz as JBL recommends, but it's making a nasty rattling sound. Has anyone ever gotten this? I'm taking the 2242H out of the cabinet tomorrow to see if it's the driver or the box, but it sounds like the driver. I've never had a voice coil rub before, so I don't know if that's what this is. The bass isn't muddied or bad sounding; rather, it sounds great but has that rattle to it. Are there any parts of the woofer that would make it prone to rattle and, if so, how would I check to see which part of it is broken?

[mech986]

Was the driver securely bolted or clamped down to the baffle?

Carefully examine the dust cap and the accordion surround for any tears or irregularities. With the driver out of the box, check the tinsel leads and make sure they have freedom of movement away from the cone and frame. Check the spider all around its circumference to be sure its completely glued down and not loose.

Other than that, it could be the Voice coil has partially separated from the cone, debris has gotten into the gap, or the voice coil has been over driven and is rubbing at some point. Play outside and see if it rattles, then follow the noise.

If you play it outside of the cabinet and it sounds ok, then check inside the cabinet for any loose bracing or vents, or any material other than the fiberglass fill. Wonder if a toy dropped into the vents could resonate??

[JuniorJBL]

My friend had a dented dustcap and it rattled. He had a new on put on and the rattle stopped.
That woofer has an insane amount of energy when a decent amount of power is applied!!;)

[subwoof]

bought an L200 set that was used in a basement play room for years. One had a weird rattle when the woofer was in the box and it defied detection with the usual audio generator sweep. Turned out that a few ping pong balls made their way into the port and under the fiberglas batting.....go figure...

[Silas]

bought an L200 set that was used in a basement play room for years. One had a weird rattle when the woofer was in the box and it defied detection with the usual audio generator sweep. Turned out that a few ping pong balls made their way into the port and under the fiberglas batting.....go figure...

This is what I initially thought it was since I had to fish out a ball earlier. However, that didn't stop the rattling.

I've taken it out of the box and done some testing. It is definitely the driver. I can't, however, for the life of me figure out what is causing this obnoxious sound. Everything seems to be in order except the surround ribs make a strange sticking noise when I move the cone up and down with my hands. However, this seems to go away at loud volumes and is replaced by the sound you'll hear in the video I've linked to. This is a 30Hz tone I'm playing and the volume is nowhere near 800W, I'm guessing. My Denon 3311CI is at -18dB and the EP2500 which powers the driver is a the 3:00 position in Bridged Mono. I'm guessing It's pushing no more than a couple hundred watts, if even that.

YouTube Clip (http://youtu.be/YDnjjr8K7yM)

From what I've gathered, it sounds like it may be bottoming out. I don't hear or feel any voice coil rub when I push the cone with my hand, so it seems that this is the only logical conclusion. I'm just surprised that it may be doing this since it does it even at low volumes.

[grumpy]

Difficult to assess via a cellphone, but I doubt it is bottoming out... Generally a very scary sound.
loose/poorly located tinsel leads can make a sound like that, as can other loose bits. No splits along
the surround? (Seems unlikely) possible to take it to a service center for eval?

[Silas]

Difficult to assess via a cellphone, but I doubt it is bottoming out... Generally a very scary sound.
loose/poorly located tinsel leads can make a sound like that, as can other loose bits. No splits along
the surround? (Seems unlikely) possible to take it to a service center for eval?

I looked for splits along the surround and I couldn't find any. Now, that doesn't mean they don't exist, but I would have thought they'd be somewhat obvious to make that loud of a noise. There's a service center about an hour and a half away that I may have to go to if I can't fix it myself.

What are the tinsel leads and other loose bits you mention? I have a better mic but it's a real pain in the booty to get set up. What should I do to check for other loose things? I can carefully cut out the dust cap with an Xacto knife to see if anything is in the voice coil, but I'm not sure that's necessary. I have speaker glue left over that I can use to re attach the dust cap.

[Silas]

UPDATE: I did some more testing. This is now very weird to me. It seems as if the sound is coming from the surround, but I can't figure out where. It's not cracked and there isn't anything in the surround that I can tell, but the rattling seems to go away when I push on the cone gently when it's playing. I also did some more low volume testing and it in fact does work without rattling when at low volume, contrary to what I said earlier. It's still there, but much, much quieter, something I could probably live with. Any ideas?

I forgot to mention, the sound appears to be coming from the place where I put my thumb in the below video. When it's not hooked up to an amp, I can make the surround make a crackling noise, almost as if glue isn't sticking all the way and comes up a bit when I move the speaker. However, I can't see anywhere where the surround may have come unglued...

I've uploaded a new clip showing the sound when I gently push on the cone while it's playing.

YouTube (http://youtu.be/JdryyB1HGVY)

[hjames]

Subwoof had an anecdote about non-native stuff he found inside a speaker cabinet. It might make sense to lay the speaker cabinet on its back, remove the screws (carefully!!) and lift the driver to see if there is anything behind it or if anything has settled into the frame.
Could save a lot of wild speculations ...


UPDATE: I did some more testing. This is now very weird to me. It seems as if the sound is coming from the surround, but I can't figure out where. It's not cracked and there isn't anything in the surround that I can tell, but the rattling seems to go away when I push on the cone gently when it's playing. I also did some more low volume testing and it in fact does work without rattling when at low volume, contrary to what I said earlier. It's still there, but much, much quieter, something I could probably live with. Any ideas?

I forgot to mention, the sound appears to be coming from the place where I put my thumb in the below video. When it's not hooked up to an amp, I can make the surround make a crackling noise, almost as if glue isn't sticking all the way and comes up a bit when I move the speaker. However, I can't see anywhere where the surround may have come unglued...

I've uploaded a new clip showing the sound when I gently push on the cone while it's playing.

YouTube (http://youtu.be/JdryyB1HGVY)

[JuniorJBL]

UPDATE: I did some more testing. This is now very weird to me. It seems as if the sound is coming from the surround, but I can't figure out where. It's not cracked and there isn't anything in the surround that I can tell, but the rattling seems to go away when I push on the cone gently when it's playing. I also did some more low volume testing and it in fact does work without rattling when at low volume, contrary to what I said earlier. It's still there, but much, much quieter, something I could probably live with. Any ideas?

I forgot to mention, the sound appears to be coming from the place where I put my thumb in the below video. When it's not hooked up to an amp, I can make the surround make a crackling noise, almost as if glue isn't sticking all the way and comes up a bit when I move the speaker. However, I can't see anywhere where the surround may have come unglued...

I've uploaded a new clip showing the sound when I gently push on the cone while it's playing.

YouTube (http://youtu.be/JdryyB1HGVY)


I have found that when you touch the speaker and the noise stops then there is something loose as Grumpy said. I have also heard torn surrounds make that noise as well.
I would continue to look for "Loose bits" front and back.

[Silas]

I fiddled with it some more today. I haven't found any loose bits, but I do think I found the source of the problem. It sounds like a very small section of the glue holding the surround to the cone has loosened, but is still tacky. When the driver moves, it reattaches and then is pulled apart, making the noise I've been hearing. I'm not sure there's anything I can do about this so I'm just going to leave it and call it a day.

[hjames]

I fiddled with it some more today. I haven't found any loose bits, but I do think I found the source of the problem. It sounds like a very small section of the glue holding the surround to the cone has loosened, but is still tacky. When the driver moves, it reattaches and then is pulled apart, making the noise I've been hearing. I'm not sure there's anything I can do about this so I'm just going to leave it and call it a day.

Good work! Maybe there was some kind of oil/grease in that
area when they were first assembled and it never quite set up right.

Best guess would be to use something like denatured alcohol SPARINGLY
to clean that stretch of glue off, then reglue that area.

[subwoof]

I have also seen ( esp on the triple roll variants ) where the excess gasket glue oozes out and makes contact with the outer roll - and it sticks/unsticks just like you mentioned....

A good, careful removal with some MEK and a Qtip will work wonders.

even the factory is sloppy on this from time to time. Had a number of older E140's with that issue once.

[Silas]

I have also seen ( esp on the triple roll variants ) where the excess gasket glue oozes out and makes contact with the outer roll - and it sticks/unsticks just like you mentioned....

A good, careful removal with some MEK and a Qtip will work wonders.

even the factory is sloppy on this from time to time. Had a number of older E140's with that issue once.

This is what I assume it is. Since I was really only worried that it was mechanical damage, I'm just putting it back in the box now. I don't have the patience to keep looking for another few hours for a bit of phantom glue - believe me, I looked for it earlier and couldn't find the culprit - so I'm just going to leave it and deal with it until I move into a new house where I can dedicate a room for a theater.

Garr this is frustrating, but I'll live with it. :banghead:

[DogBox]

Hi Silas,

I bought myself some 2225's and one was supposed to be crook.. Had a good voice coil by multimeter.. But had this weird noise like you say.
Turned out to be the 'spider' had parts around its circumference where it wasn't glued properly to the frame!
Putting the speaker on its back [magnet down] and gently and evenly lifting up the cone [forward motion of the cone] revealed parts of the spider were not glued properly and were "flapping" when driven with low frequency signal. Seems like you've checked everything else....

DogBox

[Silas]

Hi Silas,

I bought myself some 2225's and one was supposed to be crook.. Had a good voice coil by multimeter.. But had this weird noise like you say.
Turned out to be the 'spider' had parts around its circumference where it wasn't glued properly to the frame!
Putting the speaker on its back [magnet down] and gently and evenly lifting up the cone [forward motion of the cone] revealed parts of the spider were not glued properly and were "flapping" when driven with low frequency signal. Seems like you've checked everything else....

DogBox

Did you remove the gasket to check? The issue I had when I was looking for that is that it was very difficult to see that edge around the cone whilst moving the cone to replicate the sound. I just got annoyed and put it back. However, I'm curious to try again in a bit to see if that's what caused it. What steps did you go through to find that was the issue and how did you fix it?

[DogBox]

Hi Silas,

No, I didn't have to remove the front gasket. Actually, what I did do, was to have the speaker lying on it's back [magnet down] and connect

some music to it- at a reasonable volume, as I rotated the speaker around and held a small "torch" to where the "spider" [orange/yellow thing

with 'ripples' in it] under the cone - a bit like a CSI on the telly - showed in parts, the spider not glued down properly. After disconnecting the

music source, I could "gently" move the cone 'forward' [outward] by hand to show this 'separation'. I'm not talking about the ripple surround at the edge of the "cone" to the frame [where the mounting bolts go] like subwoof said. For that, lay the speaker 'face down' , and, with the torch
again, check where the "surround" goes to the frame [underneath the gaskets on the front] for that glue he was talking about. Truely, a
small 2 x AA cell torch is a really handy thing to be able to see "properly!" Clear as mud? :blink:

DogBox
Steve

[lbstyling]

That's weird- I found my 2242h was giving me exactly the same problem yesterday- got it out and found the same problem!