Reglue your port with a flexible sealant. You’ve pointed us to that problem since early on in this thread and having just shown us that by stiffening it, you have eliminated the resonance, it seems straightforward.
What xx82 has said in the post above makes sense.
Keep in mind though that if you are getting audible port chuff, you are asking too much of these speakers.
Keep in mind though that if you are getting audible port chuff, you are asking too much of these speakers.
Use a glue that sticks to wood and plastic. I see no need to remove the plastic part first, just smear it over both parts from the inside all around the baffle. Epoxy should stick to both materials, just like PU-wood glue. This modern PU wood glue hardenes from the moisture in the wood and air and is really nasty sticking to allmost anything else. Like your fingers... Don't try silicone.
I have a pair of 760 (not the i) and they really benefit from the use of a small subwoofer. I can't speak to the 760i, but my 760 really are not doing too much below 70Hz or so, and pushing them to make lower bass will result in a lot of port noise.
Deburring the port edges from inside with sandpaper seems to have eliminated all crackling even at loud volumes, it probably was the sole cause of the crackling, i probably could take out the polyester wadding and they'd play fine. But it's really odd that non deburred port edges became a problem to them only after 2 months.
I got Jamo SUB 200 paired with them.
I just wanted them both to sound about the same without the severely noticeable crackling in one of them. I'm fine with them chuffing, but not this high pitched crackling noise one of them made.
I got Jamo SUB 200 paired with them.
Sounds to me like you have an intermittent fault somewhere. Taking things apart and putting them back together must be changing the state of the fault.
Sometimes it takes a certain song to highlight a deficiency like this. It might take a while for that song to pop up in your rotation. Once you hear it, it then grates on your nerves. Is there a possibility that was the case here?
No, i listen to drum n bass mostly, and before getting a sub i used to play them really loud, so i'd have noticed the crackling from the start.
I hope that't not the case and i dont think that it is, because people i have sent to repair it to have taken it apart and put it back, and me myself has done so many times, i even switched the components between the speakers a few times, i'm sure i'd have stricken luck where it doesn't crackle before i started messing with polyester wadding inside cabinet and around the port. But time will tell.
If you still have the polyester wedged between the port and the cabinet wall, there's the possibility that you had two issues. Maybe the port started rattling against the sidewall more recently, but there was a lower level chuffing related to the burs all along that you didn't notice until you started listening more critically. As you say, time will tell.