I made my subwoofer an year ago. It sounds good. but recently when I touched it while it was on, I found vibrations. when It was newly built I never checked if it vibrates. I used 18mm MDF with 200mm woofer. I wonder why does it happen so? It happens even at the volume level is low.I am attaching the pic of the sub woofer cabinet for better understanding of its structure. please help me to understand the problem. 
Attachments
All woofers have moving mass which causes some degree of vibration.
Try sitting on the enclosure and see if you still feel the vibration.
Feel the floor, it probably is vibrating as much as the cabinet.
Excessive cabinet wall flex, which would be unlikely in a cabinet as small as yours with 18mm MDF, can be fixed with bracing.
Since it sounds good, don't mess with it
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I have 3 Karlson speaker enclosures, 2 of them 15" plus a 4" tweeter, and a 3rd 12"+4". Although the construction is very rigid per se, and the speakers ar rated for 70W, and I´m using only 12W max from TDA2006, I can tell you allways a small amount of vibrating in the walls must be, because internal pressures are very big and the waffle walls are not perfectly rigid. You can do a simple test to see what happen in it. I read it in some audio magazine from 70's in Argentina wrote by Saul Sorin or Julio V. Rueda (I believe): you need an audio generator and some dry sand. Put the cabinet in some fixed location, on the floor. Place over the top, some sand, set the generator in the lower frequency as you can, and increase it slowly. You can see that the sand separates and joint forming the nodes and peaks of the standing wave, and if you continue augmenting frequency can see the harmonics of it. Try this in the faces except that one containing the speaker. If the frequency of all faces are equal, then try some absorbent material inside the cabinet, but not near the walls, because it doesn´t do nothing, air velocity near the wall is zero. And, you can try some strengthen or encourage (Sorry if my english is not so good) by means of a piece of wood in the places where standing waves are most important. But have in mind that zero vibrating can be done if and only if rigidity of walls are infinite.
Good luck.
Good luck.
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Thank You for the help and suggestions.
I would try sitting on it and see if it vibrates. sure.
I will work this out too will need couple of days.
Yet the amplifier is not placed on subwoofer cabinet so sure thats not the reason.
Try sitting on the enclosure and see if you still feel the vibration.
Feel the floor, it probably is vibrating as much as the cabinet.
Excessive cabinet wall flex, which would be unlikely in a cabinet as small as yours with 18mm MDF, can be fixed with bracing.
Since it sounds good, don't mess with it
I would try sitting on it and see if it vibrates. sure.
I will work this out too will need couple of days.
Yet the amplifier is not placed on subwoofer cabinet so sure thats not the reason.
Ah, I was just guessing at the use for the volume that appears to be seperated off.
A similar problem was discussed a few weeks ago; do you happen to see this?
http://www.diyaudio.com/forums/subwoofers/203261-subwoofer-box-rattle-issue.html
http://www.diyaudio.com/forums/subwoofers/203261-subwoofer-box-rattle-issue.html
Bracing used with some lining of Stuffing will give better results ... Add Stuffing in box will also helps reduce unwanted resonance n vibration .....
My new subwoofer that just completed recently used quite amount of bracing but no stuffing .... but i don't find any kind of vibration problem ....
Anyway ... it is up to u to include the stuffing o not ... but i strongly suggest to do so ...
My new subwoofer that just completed recently used quite amount of bracing but no stuffing .... but i don't find any kind of vibration problem ....
Anyway ... it is up to u to include the stuffing o not ... but i strongly suggest to do so ...
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