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#1
06-06-2015, 02:08 PM
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Reducing speaker cab resonance
I have 2 polycarbonate Carvin cabinets with 12" speaker and tweeter. They sound pretty good and have lots of clarity, but there is definitely some hollow-ness. I looked inside and there is no fill whatsoever. Completely hollow except for components. Anybody have any idea what I can fill speaker cab with?
Thanks in advance. 
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#3
06-06-2015, 07:56 PM
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Poly quilt batting also works well. In fact it looks identical to many fills I've seen in cabs on which I've worked. You can get it at WalMart or Kmart or sewing shops. The sheet can be easily cut and folded without skin irritation:
http://www.walmart.com/ip/Morning-Gl...x-110/19397508 I use it in my guitar cabinet and it works very well! Good luck!
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#4
06-06-2015, 08:49 PM
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I second the polyester fibrefill idea. Also, anything you can do to stiffen the cabinet walls will help as well. And play with the ports - You may find that a loose plug of fibrefill in the port will improve things at your typical volume level.
__________________
-donh- *everything* is a tone control
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#5
06-06-2015, 09:00 PM
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Quote:
Thanks!
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#7
06-06-2015, 10:26 PM
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I can understand adding a fill to a sealed enclosure where enclosure space isn't adequately sized to match the speaker driver, thus making the speaker perform like it's in a larger enclosure, but in a ported speaker enclosure I don't see the benefit of adding any fill?? What is the result your trying to achieve with a fill? On a side note, too little or too much can have negative impact.
If your speaker cab is resonating beyond your liking, you could try to line the walls with a heavy sound deadening matting which is going to add mass to the cabinet walls. Adding insulation or polyfill is not going to do this. Last edited by Xtremca; 06-06-2015 at 10:36 PM.
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#8
06-06-2015, 11:42 PM
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Quote:
I have run the measurements of hundreds (perhaps thousands, I never kept track) of speakers thru box-matching programs and found that most PA speakers are (1) mis-matched to any box and (2) tend to prefer small sealed boxes and large ported ones. So they tend to end up in small ported boxes. Yaaa? Many many years ago I was a bass player in a horrible dive-bar band and for good reasons got playing with my Sunn bass bin with dual JBL D140s in it. I ended up blocking off half the port (hold boards over the port, play the bass, wash, rinse, repeat) and suddenly had a punchier bass bin than anyone else in town. I now know why, and the full workup is past the limits of a forum post. But it worked, nothing ever blew up, and fun was had by all. A bit of fibrefill or foam stuffed in a port will make the port an aperiodic damping device and may just make the speaker happier. Aperiodic damping (sorta) works as a port at low power levels and a sealed-box at higher power levels. This just happens to be what many raw PA speakers tend to like, so it is worth a try. If they hate it they will tell you - just listen. This trick is common with some high-end stereo speaker manufacturers, they ship the speakers with a carefully cut foam plug and tell you to try it and see if you like it. So now I'm telling you. To stiffen the walls, add bracing. Use imagination, and understand that bracing reduces cabinet volume. Rubber cabinets move and add a time-delayed out-of-phase signal to your desired sound, rob clarity, and make things sound 'boxy'. An ideal cabinet has infinite stiffness.
__________________
-donh- *everything* is a tone control
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#9
06-07-2015, 06:29 AM
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Spot on!
Years ago I began dampening my guitar cabs because it reduces reflections from the inside of the cabinet, yielding a smoother tone from the cab. The quilt batting needs to be folded a couple of times and stapled to the inside of the cab, being careful to keep it out of the way of the port. In my experience, the fill isn't going to help with cab rattles, or poor cab design. But ported or not, it does tend to make a more even sound.
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