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Discussion Starter · #1 ·
I have an older (8-10 years) Sony 12" sub that I replaced the driver with a cheapie ($30) from parts express a while back. (Models #'s escape me at the moment)


I'm finally putting together a decent home theater after using a HTiB for a few years and I decided to pull this sub out of the closet and give it some use.


It seems to bottom out pretty easily. I was told by a coworker that I should block the port to seal it up, that this would help the driver from being too loose. Do you think this is worth a shot or should I move onto another plan?


Other plans:


1. Poly Fill? I'm not sure if this will do much for this specific issue, but it should help the sub sound better anyways, correct?


2. Replace driver again, with something decent this time..


3. Replace the whole sub with something new, like a Polk PSW10 or equivalent...


My system thus far is:


Harman Kardon AVR 254

Polk Monitor 50 (front)

Polk CS1

Polk Monitor 30 (Surround)


and this sub.


Thanks in advance for any suggestions.
 

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I'd go with option 3. Option 1 won't do anything to help your issue and option 2 is a waste of time and expense unless the driver is perfectly matched for the size enclosure used and the amp your using it with, you could end up with the same results or worse. You can get good subwoofers for HT starting at the $200 and sometimes slightly under price range. Room size would be the biggest factor in the budget.


You can try plugging the port on the sub you have and why not, it's free but whether it helps with the overextension problem or not you're still not going to have a sub in the performance category of going with option 3. Plugging the port will also sacrifice the subs output capability across the entire frequency range.
 

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closing the port will actually make it more likely to bottom out.
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by mcjasonb /forum/post/17034455


closing the port will actually make it more likely to bottom out.

Do you mind explaining how? (not doubting you, just looking for more knowledge)
 

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Quote:
Originally Posted by clintz /forum/post/17034467


Do you mind explaining how? (not doubting you, just looking for more knowledge)

in a ported enclosure above the port tuning frequency and the closer to it, there will actually be more pressure inside the box. i know it doesn't seem like that would be the case, but trust me, it is. i don't know all the details behind it, but hopefully somebody else can explain in more detail.
 

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You would be less likely to bottom out the woofer after it is sealed when applying equal amounts of power. The problem is that you will lose efficiency when sealed and therefore would need to apply more power to get the same output which again opens up the possiblity of bottoming.


Time for a new sub.
 

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Discussion Starter · #7 ·
I was planning on getting a new sub to begin with, but I felt that I should give this one a shot at redemption... I'll try it a few different ways and if I don't like it, it is going on craigs!
 

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Quote:
Originally Posted by mojomike /forum/post/17034926


You would be less likely to bottom out the woofer after it is sealed when applying equal amounts of power. The problem is that you will lose efficiency when sealed and therefore would need to apply more power to get the same output which again opens up the possiblity of bottoming.


Time for a new sub.

Unless of course the overexcursion is happening below tuning in which case blocking the port would "solve" the issue (you'd still lose efficiency around tuning as said though). That's not to say that you don't need a new sub but it's worth a shot and is free to try.
 

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Quote:
Originally Posted by lennon_68 /forum/post/17035142


Unless of course the overexcursion is happening below tuning in which case blocking the port would "solve" the issue (you'd still lose efficiency around tuning as said though). That's not to say that you don't need a new sub but it's worth a shot and is free to try.

I was thinking the same thing. What is the tuning frequency of the subwoofer? Is there a high pass filtering out frequencies below tuning? If not, the driver will "unload" and bottom out on frequencies that are below the port tuning of the sub. Sealing the box will help if this is the case, but as others have said, you'll end up with less output that way. Also, what mojomike said was correct as well - if you add more power to recoup the output you lose by sealing the box, you'll also open up the possibility of bottoming out again anyway. Like most others here, I think it's time for a new sub.
 

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I run dual dayton sub100's in one of my smaller systems.. Plugging the ports on those made them sound quite a bit better..
 

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Discussion Starter · #11 ·
Well, I tried it plugged and unplugged, and TBH it sounds better unplugged. As long as I don't turn it up loud enough to shake the walls, it doesn't bottom out, and it actually sounds pretty good!


I bought some poly-fill that I'm gonna toss in there just for fun (why not?)


I'll still upgrade when I have some extra cash, but for now, this will do.. Thanks for the suggestions everyone!
 
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