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Subwoofer Rattle and Distortion

post #1 of 7
2/6/12 at 5:47am
Thread Starter 
I've been looking on Google for any information with subs that rattle (sound distortion) at certain frequencies, but thought I would ask here also. The Google results have not been too clear.

I have two subs in one rectangular room. At first I had an old Klipsch sub (down firing) and a newer Klipsch I got last year. At certain frequencies (when there was a lot of bass in a movie soundtrack) the old sub would rattle. It was at the mid position (volume-wise), and the Denon receiver had been calibrated with their Audissey process.

So, I decided to swap the new Klipsch for an older Energy sub I have. That one also rattles, just louder, since it's more powerful.

I'm just wondering: are these subs rattleling because they're old and need to be replaced? Or is something else going on here?

Any help would be GREATLY appreciated. Thanks!
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post #2 of 7
2/6/12 at 5:55am
Sounds like something in the room is rattling not the subs.
It can be difficult to find the culprit, play track that reproduces the noise with all the other speakers turned off.
Once found then you can try to fix.
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post #3 of 7
2/6/12 at 6:11am
I also think it's probably your room, or something in it, that is rattling. Not the sub's themselves. You should do a frequency sweep until you find the frequency at which things start rattling. Once you have it, crawl around the room until you find what is causing the noise.

I've noticed the dishes in my kitchen would rattle pretty bad at around 38Hz.
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post #4 of 7
2/6/12 at 6:26am
Quote:
Originally Posted by MasterofBlasting View Post

I also think it's probably your room, or something in it, that is rattling. Not the sub's themselves. You should do a frequency sweep until you find the frequency at which things start rattling. Once you have it, crawl around the room until you find what is causing the noise.

+1 This is sound advice.
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post #5 of 7
2/6/12 at 7:50am
Thread Starter 
Quote:
Originally Posted by jackbuzz View Post

Sounds like something in the room is rattling not the subs.
It can be difficult to find the culprit, play track that reproduces the noise with all the other speakers turned off.
Once found then you can try to fix.

Thanks for the quick replies, guys!

It's definitely not something in the room that is rattling. I have heard that before and know how that sounds. What I see (after taking the Energy sub's grill off, is that when the bass response is high, the cone is moving in longer vibrations (more air is being pushed) and then at some point the cone does not vibrate normally----it's like it's vibrating due to it's own vibrations (kinda like a heart that does not beat in rhythmn.

I finally got brave and pulled off a foam circle that was covering the outer screws. I tightened a few of them more and ran the channel level test from the receiver again. This time the sub did not rattle like it did the last time I ran that channel level test for the SW. So, maybe it's better now with the screw tightening. I'll check later with an actual movie and see.
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post #6 of 7
2/22/12 at 6:55am
Thread Starter 
I ended up replacing the sub with an RW-12D sub from Klipsch. Moved that one to a back corner and the old sub across from it. One night the bass was so much that it knocked over a glass cup in the kitchen counter (about 20 feet away).

I guess my problem is solved. I did lower the old sub's volume a LOT. I think it does have a problem with the amp in it, as it always has a low hum sound.
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post #7 of 7
2/22/12 at 8:09am
Are these sealed subs? Do you have model numbers?

Here's my experience with sealed subs:

I had a rattle a year or so ago. This sub had a sealed amp section within the sub's main enclosure, in an effort to seal off the plate amp's electronics from the back pressure of the driver. After taking everything apart, I noticed that the hot glue applied to the edges where the amp box met the sub enclosure was brittle and gone in some places. I picked out all the remaining hot glue around the entirety of the enclosure and used a nice heavy bead of caulk around every edge on the interior of the thing. Wow, what a difference! It was like night and day.

I bought another matching sub off ebay and the first things I did was to tear it all down and recaulk it. These are 12 year old subs, and they sound brand new. Keep in mind, if you caulk the interior seams, let the caulk cure for at least 24-48 hours before reinstalling your driver. The offgassing can eat away at some driver surrounds.

Also, when you reinstall the driver, make sure to scrap off all the dried crap adhesive off the driver flange. I reinstall using a nice bead of "rope caulk" weatherstripping on the driver. A lot easier to remove if you ever need to get the driver out.

Since then, I had a plate amp die on one of them, so I replaced both amps with matching new ones, and moved them outboard in their own enclosure. (Even less risk of something rattling.)

For 12 year old subs, with original drivers I can play X-Men First Class, Inception, etc. at near reference levels, (-5 or so on the AVR), with absolutely NO rattles. (I'm also using AntiMode 8033). If you have Audyssey or the like, you should be okay.

Hope this helps.
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