I just completed my first project, a cabinet for my Bass guitar and I find that for notes below the low G (49 hz) the woofer rattles.
My box is made from 3/4' marine grade plywood 14.75" x 23.5" x 15.75", approximately 2.45 cuft. For the ports I have two, 3"dia 5.8" long.
I have two drivers, an eminence 12" Delta 12LFA and an eminence alph8MR with a 2 way crossover. The box is stuffed with 2 lbs of Acoustastuff.
The box is solid and the drivers held in plase with 3/4" #8 screws
Is there anything I can do short of starting over, perhaps tune the ports?
(If you read this in the Music forum sorry for the duplication, I realized after the fact it probably belongs here)
My box is made from 3/4' marine grade plywood 14.75" x 23.5" x 15.75", approximately 2.45 cuft. For the ports I have two, 3"dia 5.8" long.
I have two drivers, an eminence 12" Delta 12LFA and an eminence alph8MR with a 2 way crossover. The box is stuffed with 2 lbs of Acoustastuff.
The box is solid and the drivers held in plase with 3/4" #8 screws
Is there anything I can do short of starting over, perhaps tune the ports?
(If you read this in the Music forum sorry for the duplication, I realized after the fact it probably belongs here)
Have you figured out *what's* rattling?
Idea: grab a tape recorder (or a friend) and feed a bunch of low Gs at the amp. Stick some earplugs in your ears so you can get nice and close without damaging your ears. Push on things 'till the rattle goes away. Then figure out how to fix it.
If you're lucky, it might be the woofer shaking against the wood... in which case you might be able to fix it by mounting it with more pressure... either a gasket ring or maybe some machine screws with T-nuts.
Wes
Idea: grab a tape recorder (or a friend) and feed a bunch of low Gs at the amp. Stick some earplugs in your ears so you can get nice and close without damaging your ears. Push on things 'till the rattle goes away. Then figure out how to fix it.
If you're lucky, it might be the woofer shaking against the wood... in which case you might be able to fix it by mounting it with more pressure... either a gasket ring or maybe some machine screws with T-nuts.
Wes
I don't have access to my normal moddeling tools, but from what you have given, and an applet I found on the web, I think the tuning freq of your box is around 43Hz..... you maybe playing notes that are at or below the box resonant freq, which is somewhat of a no no for a vented enclosure. effectively the cone will be flapping about uncontrolably going past it's excursion limits.
I'm surprised at the relatively high fs for this woofer.. 45Hz seems rather high for a 12".... note the datasheet says usable freq range is 45Hz to 3Khz you probably need to limit it to that, maybe put in a high pass filter at 45Hz or just don't play anything lower than 45Hz....... probably not what you wanted to hear
Tony.
I'm surprised at the relatively high fs for this woofer.. 45Hz seems rather high for a 12".... note the datasheet says usable freq range is 45Hz to 3Khz you probably need to limit it to that, maybe put in a high pass filter at 45Hz or just don't play anything lower than 45Hz....... probably not what you wanted to hear
Tony.
Re: Where is the rattle coming from
Though it could be any number of problems I find that low freq. freq.-specific buzz/rattle is usually induced by a failure of the diaphram connection to the surround (aka a glue problem), or sometimes in the case of an acordian surround a failure of the surround itself (rubing against itself). The best way to check for this problem is playing the annoying freq. at moderate volume and listening closely to the driver to hear where the buzz is coming from.. then placing your thumb against the surround area where the problem seems to be comming from to mechanically dampen the problem. If it reduces the buzz then thats your problem. The best solution would then be to replace the driver. Alternativly you could try dampening with something like a silicone caulk in the problem area.
ADG said:
Though it could be any number of problems I find that low freq. freq.-specific buzz/rattle is usually induced by a failure of the diaphram connection to the surround (aka a glue problem), or sometimes in the case of an acordian surround a failure of the surround itself (rubing against itself). The best way to check for this problem is playing the annoying freq. at moderate volume and listening closely to the driver to hear where the buzz is coming from.. then placing your thumb against the surround area where the problem seems to be comming from to mechanically dampen the problem. If it reduces the buzz then thats your problem. The best solution would then be to replace the driver. Alternativly you could try dampening with something like a silicone caulk in the problem area.
Whilst the driver is running, run your fingers around the surround. If there is a loose joint then the noise will stop when you touch that part. Then, you can gently lift it and reglue, or if still under waranty, send it back for a replacement.
You could also try stuffing the port with an old rag or similar, if the noise goes away, then as mentioned above, the driver is unloading below Fs and is unsuitable for your cab.
You could also try stuffing the port with an old rag or similar, if the noise goes away, then as mentioned above, the driver is unloading below Fs and is unsuitable for your cab.
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