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General speaker questions for audio and home theater.

RE: Mechanical buzz in JBL D123-question for speaker repair gurus

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.

Edits: 06/10/17 06/10/17 06/10/17 06/10/17 06/10/17 06/10/17

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