Njord

I recently took my sub box out because I thought it had a leak (sealed box) I didn't have any glue or silicone but I had lots of b-quite lying around (I originally glued and put silicone around the inner corners when I built it). So with a heat gun I put some b-quiet around the inner corners/edges on the inside of the box, making a seal. I also put some directly behind the sub. Put the sub back in, nothing changed still sounds the same (bad).

Turns out I didn't have a leak but a dead voice coil. So I put a new sub in(same sub) and it sounds good, alot louder then before (as it should. 4ohm VS 2ohm). At low volumes it sounds just like it did when I first built the box (when the original sub worked) But as soon as I turn it up, it sounds hollow, almost like something is rattling inside but its not. Sounds like a deep tin can sound (if you can imagine that) It doesn't seem to be a gradual thing either. At 55 volume it sounds fine, but at 56 it sounds like crap. Back when I first built this box it went a lot louder and sounded better.

I can't see how adding b-quite around the inner edges would negatively affect anything, but I'm wondering if anyone might say differently. I don't really want to remove it as I've removed the 2 subs about 5 times now and I'm running out of new places to screw into. And sanding the old screw holes down is such a pain.

To add, when I first put the new sub in it sounded a lot worse. It turns out it was because I didn't sand down the old screw holes and the bumps were preventing the sub from sealing to the box(I could feel air escaping). After sanding it goes louder but when I turn it up that same sound comes back, but there is no leak around the sub.

Nothing changed since I built the box back in the summer, other then the sub dying. New sub seems fine; Voice coils read out as they should.

sunfired

iTrader: (-1)

when you R&R your subs in box, why is it your making new holes and not just putting the screws into existing holes? I would get some wood filler and seal those extra holes right up.
Anyways... just a guess but could any of the panels of the box have came loose? or flexing, there by losing some ummph?

Njord

I find when putting screws back in the same hole the screws tend to spin and not grab.

I use fairly short screws and they don't actually go all the way through the 3/4" MDF, and when putting the sub back on the holes are covered by the sub. Might be an idea though.

I'm going to try right now tightening the screws on the box, some might have came loose. I doubt the box is flexing though. It's only 500wRMS.

Thanks for the suggestions.

Njord

The screws on the box are defiantly on there tight.

Synyster_13

if the above mentions don't help maybe trty building a new box with thicker mdf? dependong on the size of the sub it may just be moving enough air inside that sealed enclosure to flex the walls and lose some of the SQ cuz of it

Njord

Its a 10" Alpine type-R running at 500WRMS. Box is ~1.1 ft^3 with 3/4" MDF. The box is bigger then alpine recommends but when I first built it, it sounded great. If I can't fix this problem I will probably end up rebuilding it, I still don't think the box is flexing. The box is too big for that amount of power for it to be flexing (and It never did before)

Any other suggestions other then rebuild the box?
Thanks again for the help.

luke99

why not just resin the inside of the box

Denonite

iTrader: (1)

can you try the sub/box combo with another system or amp? If the box and sub are ok, then maybe it's an electrical/amp/signal problem.

luke99

or hes just overpowering the subs hes putting in there

Njord

Luke99: Never played around with resin before, and I don't have any.

denonite: it could possibly be the amp, but its doubtful as it still plays fine at lower volumes and it hasn't given me a reason to suspect it. Electrical should be fine, my other 1000Wrms runs the front speakers fine. I metered my voltage before and it never dropped below ~13v. Though It might be a setting on my deck for the sub ouput. I've been playing around with it and I think its to what it was before (when it sounded good)

Luke99: It could be. I have the gains on the [sub] amp down at 'normal' (labeled as such). At this setting previously the sub went alot louder.

To the original subject, no one has ever experienced negative affects by adding sound dendener to the inside of the box?