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In Reply to: RE: Mechanical buzz in JBL D123-question for speaker repair gurus posted by mac55 on June 09, 2017 at 20:55:28
You just cut the cap at the very outer edge ...maybe 1mm
away from the crease. You don't need the lip to glue it back
on. Set it on the cone, then run the bead of glue around it.
I don't think it's a surround problem, but one of the three
The mystery deepens. I dug out an HP signal generator (yes, I realize I should have done this much earlier) and connected it to my amp and one of the speakers. No remote buzz anywhere in the audible spectrum, even at moderate power. However, very oddly, there is a resonance at 120 Hz. In other words, if I sweep just north or south of 120, I can hear beats, which increase in tempo as I sweep north or south. It's not at all like it manifests as buzz when playing, but I cannot account for it. And it's present in both speakers! Any thoughts?
Update: I just tried running the amplifier and the HP signal generator on a Oneac power conditioner I run my stereo through, and the resonance is still there.
Update #2: I just tried another speaker, a 12" alnico Marsland, and I can detect beats around 120 Hz, perhaps to a slightly lesser degree, but they're there.
Update #3: I just realized that it's plausible the 120 Hz (60) resonance is coming directly from the power supply of HP tone generator, which is at least 40 year old.
Yep, bad 40 yr. old filter caps in pwr. supply.
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