Just a thought but would facing the side of the speaker facing up and putting a thin layer of sand or salt on it while doing sweeps tell you anything? Also look into CLD bracing (might be harder to do well on an already built cabinet. Cheers.
By the way here is my bracing story four years ago... Nearfield measurement of the woofer, looking at distortion in REW showed the result. No options were tested.
https://www.diyaudio.com/community/threads/jbl-lsr305-tweaking.320206/
https://www.diyaudio.com/community/threads/jbl-lsr305-tweaking.320206/
Food for thought ... how much panel vibration(s) get canceled by other vibrations? This is why I think a laser vibrometer is going to tell a guy more than using a contact mic. Trick, like Pano tried, is dumbing the idea down for cost. Maybe tape a baby rattle to the panel?
Is there a device that registers a voltage when shook? (don't worry Pano .. I won't post the "shake weight .gif" 🙂
Is there a device that registers a voltage when shook? (don't worry Pano .. I won't post the "shake weight .gif" 🙂
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I'm sure " Remlab " did some "acceleratometre testing of loudspeaker cabinets " a few years ago. What about lying your speaker on it's side, give it a dusting of chalk, blast some music through an see the resulting patterns ?
On my " cheap omnis " I tapped the cabinet before and after adding 45 deg braces in the corners, recording the sound on each occasion, the sound was noticeably higher in pitch after adding the minimal bracing.
On my " cheap omnis " I tapped the cabinet before and after adding 45 deg braces in the corners, recording the sound on each occasion, the sound was noticeably higher in pitch after adding the minimal bracing.
what do you mean the sound was higher in pitch?
the knuckle wrap or the sound coming out of the speakers?
Maybe this post and follow-ups is interesting:
https://www.diyaudio.com/community/threads/cabinet-bracing-measurements.284063/post-4554859
Also, has anyone considered using a phono pickup to sense panel vibrations?
https://www.diyaudio.com/community/threads/cabinet-bracing-measurements.284063/post-4554859
Also, has anyone considered using a phono pickup to sense panel vibrations?
The sound of the resonance was noticeably higher in pitch, but when I measured the frequencies, there was a disappointingly small difference, although I think even though there was little difference in the main frequency, the energy seemed to have shifted to higher harmonics. I think I still have the recordings, I'll see if I can post the tomorrow when I can use a laptop. To be honest, I've been disappointed at the results obtained by bracing, I'm tempted to use thin ( ie 3 mm ) and add lots of damping to see if that works. On my current build I'm also planing on adding an acoustic hood as well. One experiment was using two speaker boxes, one inside the other.
But it was your own design right?
from asking around, and being on here it’s pretty clear most don’t know quantitatively what is going on with the cabs they make with bracing.
i think they just make a few boxes , use bracing and the one which sounds best , they stick with as a part of the recipe for all their speakers.
i highly doubt most will make a cabinet with bracing, do measurements, adjust , etc etc.
some do of course
from asking around, and being on here it’s pretty clear most don’t know quantitatively what is going on with the cabs they make with bracing.
i think they just make a few boxes , use bracing and the one which sounds best , they stick with as a part of the recipe for all their speakers.
i highly doubt most will make a cabinet with bracing, do measurements, adjust , etc etc.
some do of course
Yes it was my design, I'm the only one mad enough to do duch weird things.
Someone ( sadly I forget who ) came up with the brilliant idea of using an automatic centre punch on the speaker enclosure, this would give a repeatable " hit ", and the result could be measured, perhaps with just a db meter.
Someone ( sadly I forget who ) came up with the brilliant idea of using an automatic centre punch on the speaker enclosure, this would give a repeatable " hit ", and the result could be measured, perhaps with just a db meter.
Offtopic, practical tips... when you think there is something resonating. First take normal oñaxis measurement and look at distortion. Then use REW's tone generator and play that freq sine and use your ears and fingers to check what is making the noise. You might have to increase sound level too, to excite the resonance. Then find and test ways to fix it.
Have fun! Making scientific article about it gives higher standards for methods, documenting and reporting, but this is just a hobby forum, not ASR!
Have fun! Making scientific article about it gives higher standards for methods, documenting and reporting, but this is just a hobby forum, not ASR!