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Speaker Asylum General speaker questions for audio and home theater. |
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Speaker Asylum General speaker questions for audio and home theater. |
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In Reply to: RE: i started a ticket with JBL for repair or replacement posted by seas on December 30, 2016 at 13:27:15:
that's what i was thinking. there's absolutely nothing dampening the sub and it's nearly 100% cancellation. the cone was REALLY wobbling when it made the noise making me think it could have been reaching its maximum excursion, but i wanted to run it by someone more knowledgeable than me.i have it bridged on the amp and probably turned the input level up so it would be audible. it could theoretically be hitting 600w, but that's giving the amp credit for its ambitious 4x300w rating. it could also be clipping.
it's really hard to know just what's going on without a cabinet, like you said. i might have been pushing it to lease breaking levels without knowing it because of the phase cancellations that are strongest at the lowest frequencies.
maybe before i assume it's busted, i should get the 1.9 cubic foot box i intend to use with it and test it at the same level outside some day. if it's excursion related, an air spring will totally cure that.
i did some break in with the 4x hifonic 12" subs i used to own playing 8Hz tones on my panasonic receiver and never heard anything except subtle air whooshing, but that was using less than 100w likely. i tried breaking the JBL in with an 8hz tone, but something in the signal chain was limiting the output so the cone didn't move over a centimeter if that where the hifonics wobbled like crazy.
even in free air though, BOTH subs can get obnoxious enough to bother the neighbors. when i had the issue, my mains were playing at a conversational level with the sub just adding a bit of weight to them.
i was skeptical that a sub rated 1200w peak would be causing a sub to buzz with half if that power, BUT then again, clipping could be playing a part too.
maybe tomorrow i'll switch the crossover to high pass and put my mains on them to get a better idea what i was pushing starting at a lower level. until i get a box where i can isolate the back wave, there's no way to know for sure how hard i was driving the sub, but by vague memory, it was hitting something like 30Hz with at least a half inch of excursion, which is more than 14mm, but my hifonics did that or more too with a lower rating i think.
this is why i created the thread. at lower volumes, there isn't any audible distortion. even at that same level, the buzzing was apparent only on a few tracks.
maybe it's just not that common for people to overdrive subs in free air. i want to believe that i was just pushing it past its limits, but, there isn't that much more of an air spring in a ported box either.
i could see the cone crashing on a backwave when it bottoms out creating EXACTLY the sound i heard. in fact, i'd say it sounds more like an impact buzz than a loose rattle.
before buying a big duffle bag so i can haul it in for repair, i'll try some diagnostics and test it in the box.
PS i'm listening to the "forbidden fruit" instrumental now on headphones at max level with EQ boost plus a level boost with winamp, and there's a subtle buzz going on there too, but just not a plastic sounding one.
thanks for your input.
Edits: 12/31/16 12/31/16
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- RE: i started a ticket with JBL for repair or replacement - thump 00:35:18 12/31/16 (0)
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