What is the problem with this 2235h driver [video]?

[DingDing]

Hi,
I bought this 2235h driver knowing it might need a recone job, and I want to troubleshoot and try to fix it myself in hopes of learning something new. If it all goes belly up, it'll be reconed by a professional.

Made this video in hopes you guys could help me pin down if it has to be reconed or if I might be able to fix it myself. I think it sounds like the voice coil is rubbing, but having no experience with driver repairs I'm not sure. In the video I'm running a couple of sine wave test tones to induce the distorting sound. Please turn the volume up a bit, and the audio doesn't start right away, so be a little patient, please.



What do you guys think? Is the cone misaligned? Do you want me to make videos from other angles? If the cone is misaligned, I thought about getting new foam surround, dustcap and spider and try to realign it using a shim. Do you guys think that would be feasible?

Also, looking at the pictures, do you think this looks like a genuine 2235h cone? It doesn't have any white chalk markings at the rear of the cone.

[grumpy]

I can't determine it. Someone else may have a keener eye and more experience.

If the cone is original, it probably has been refoamed (replaced surrounds) not reconed
with a JBL kit. Those mounting gaskets scream aftermarket.

[macaroonie]

Gaskets are wrong for sure. Check to see if the spider is glued on properly , coil rub is more scratchy sounding. It would be better if you could run that at a lower frequency and not film it from the edge of the frame but straight on to the cone instead.

Try running it at 25 and 30 Hz.

A pic of the back of the cone would be handy.

M

[DingDing]

Gaskets are wrong for sure. Check to see if the spider is glued on properly , coil rub is more scratchy sounding. It would be better if you could run that at a lower frequency and not film it from the edge of the frame but straight on to the cone instead.

Try running it at 25 and 30 Hz.

A pic of the back of the cone would be handy.

M

Hi, thanks. Yes I'll do that right now.

[DingDing]

This took a little longer because it was hard to get proper lighting now that the Sun has gone down. Youtube also did no service to me by spending a ton of time compressing. I tried different frequencies, and as I was recording at 24 fps different frequencies gave different perceived slow motion effects. The distorting sound is evident throughout the frequencies tested and it seems to be following the frequency played, but doesn't get worse with higher excursion it seems. My unexperienced eyes can't see anything loose. I also did a lot of looking besides making these videos.

I'm turning it around etc late in the video above.





I hope these are of any help, and I've got no problem making new videos from other perspectives. The videos will live long after the problem is solved for anyone else who might run across the same issue in the future.

Here are some images. There is no white writing or marks on the rear of the cone itself.

[martin2395]

I think it's one of those shitty China recones! I had a pair once, they only had a small production code in white stamped on the cone but otherwise they lacked the JBL service sticker and neither had the "2235H" marking done with chalk/white marker.
Also they even lacked the mass ring and sounded totally rubbish. The foam suspension was waaay too stiff and one of them was making popping noises due to poor soldering of the VC wires.

When I look at the VC wires next to the dustcap, they look like soldered and laquered by hand, with genuine JBL kit that part is already assembled.
I'm almost sure you also have that knockoff recone, take a look at the fakes (especially the VC wires)
https://lh6.googleusercontent.com/-_...o/IMG_1477.JPG

[macaroonie]

My feeling is it is not coil rub but as you mentionthere seems to be residue in the coil area , could be disintegrated foam that found its way in through the vent or alternatively wasn't there a foam ' filter' plug in the vent. Just checked with mine , same driver and indeed therewas a foam filter on the face of the pole piece. Mine is now dust also but the drivers are not making any funny noises.
The solurion maybe is to put the driver face down and play it with your tone for a while and see if gravity helps this stuff to dislodge. It will fall into the back of the dust capand thenyou can vacuum it out through the vent.
Have you tried manually moving the cone and trying to hear any sounds of scraping ?.

[martin2395]

I had that issue with 2214H's, not the easiest task to remove all that goo from the woofer but I was lucky.

Though if it turns out to be a bogus recone I wouldn't even bother, just rip it apart and put a nice fresh JBL 2235H cone in it.

[DingDing]

grumpy: Thanks, I checked the mounting gaskets against my four other 2235h, and you're right they don't look anything like the originals. The spider looks to be very dirty (fine black dust), and when I placed my finger inside the pole vent in a 90 degree angle there was a lot of dirt buildup around the gap, so it has probably just been refoamed and something has gone wrong when aligning. Hopefully it'll be possible to realign.

Any ideas where I can get what I need to realign the cone? Hope the VC has only been misaligned and not bent into an oval shape. The basket looks to be round by my crude measurements.