Dynamat inside a sub box?
05-24-2005, 01:58 PM
#21
500 Watt CAFz'r
Join Date: Apr 2004
Posts: 756
Originally posted by Kinslayr:
Anyone ever try coating the inside of your sub box with bedliner material? It is supposed to be tough as nails, as well as reduce vibration.
Anyone ever try coating the inside of your sub box with bedliner material? It is supposed to be tough as nails, as well as reduce vibration.
It turned out wicked... WAY louder, WAY more SQ, and just better overall. The stuff isn't flat, it's bumpy, so if I wanted to I could sand down the inside of it to get rid of all the bumps...
But, I hit a 141.8 last night in my cavernous van without really trying to hard, so I think I'll leave it be for a while.
05-24-2005, 10:59 PM
#23
500 Watt CAFz'r
Join Date: Apr 2004
Posts: 756
I'm not sure, silly me, I hadn't weighed the box before, but it weighs in at a healthy 105 lbs. right now, including the sub, which if I remember right, is 39 lbs.
But ya... I like my Piper Power sub [img]graemlins/headbang.gif[/img] Makes the competition pay the Piper!
But ya... I like my Piper Power sub [img]graemlins/headbang.gif[/img] Makes the competition pay the Piper!
05-25-2005, 12:40 PM
#24
50 Watt CAFz'r
Join Date: Dec 2000
Posts: 241
Two things to consider.
The box is now non-porous, which is good.
The bed liner is designed to be flexible and not stiff (you don't want to put something big and heavy in the bed of your truck and have it break the liner, you want it to have a little give to it so it doesn't easily scrape off).
One of the three ways deadener works is by adding mass (which you did), by making it stiffer (which I'm not sure you did at this point) and by asborbing sound waves (which I'm not sure either, I suspect you did since it is now thicker).
Ultimately, you might have gotten similar results if you had made the box a little thicker (lets assume a 1/4" coat of bed liner + 3/4" MDF might yield similar results as building the box out of MDF and coating the inside of the box with some fiberlass resin to make it non-pourous.
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class). I had thought it wasn't a big deal, but if you think about it, if you push a woofer in a sealed box in, it should offer quite a bit of resistance if its in a small box. Many boxes don't since the wood used is porous to some degree.
By the way, I like the way the box looks with the bed liner. I suspect you won't have much luck sanding it down (it cures to a rubber consistancy based on the Rhino Lining stuff (had a guy who did it who had a shop next to wear I work)).
Juan
Yep, just had mine done inside & out the other day. My buddy owns Line-X Calgary South, and offered to do it for free, after I offered to hand out pamphlets at the show this Saturday [img]smile.gif[/img]
It turned out wicked... WAY louder, WAY more SQ, and just better overall. The stuff isn't flat, it's bumpy, so if I wanted to I could sand down the inside of it to get rid of all the bumps...
But, I hit a 141.8 last night in my cavernous van without really trying to hard, so I think I'll leave it be for a while.
</font>[/QUOTE]
The box is now non-porous, which is good.
The bed liner is designed to be flexible and not stiff (you don't want to put something big and heavy in the bed of your truck and have it break the liner, you want it to have a little give to it so it doesn't easily scrape off).
One of the three ways deadener works is by adding mass (which you did), by making it stiffer (which I'm not sure you did at this point) and by asborbing sound waves (which I'm not sure either, I suspect you did since it is now thicker).
Ultimately, you might have gotten similar results if you had made the box a little thicker (lets assume a 1/4" coat of bed liner + 3/4" MDF might yield similar results as building the box out of MDF and coating the inside of the box with some fiberlass resin to make it non-pourous.
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class). I had thought it wasn't a big deal, but if you think about it, if you push a woofer in a sealed box in, it should offer quite a bit of resistance if its in a small box. Many boxes don't since the wood used is porous to some degree.
By the way, I like the way the box looks with the bed liner. I suspect you won't have much luck sanding it down (it cures to a rubber consistancy based on the Rhino Lining stuff (had a guy who did it who had a shop next to wear I work)).
Juan
Originally posted by GrizZz:
</font><blockquote>quote:</font><hr />Originally posted by Kinslayr:
Anyone ever try coating the inside of your sub box with bedliner material? It is supposed to be tough as nails, as well as reduce vibration.
</font><blockquote>quote:</font><hr />Originally posted by Kinslayr:
Anyone ever try coating the inside of your sub box with bedliner material? It is supposed to be tough as nails, as well as reduce vibration.
It turned out wicked... WAY louder, WAY more SQ, and just better overall. The stuff isn't flat, it's bumpy, so if I wanted to I could sand down the inside of it to get rid of all the bumps...
But, I hit a 141.8 last night in my cavernous van without really trying to hard, so I think I'll leave it be for a while.
</font>[/QUOTE]
05-25-2005, 12:46 PM
#25
Guest
Posts: n/a
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class).
It should have been obvious considering it's effectiveness at proving nothing.
05-25-2005, 04:29 PM
#26
50 Watt CAFz'r
Join Date: Dec 2000
Posts: 241
I'm confused, would two pieces of non-porous products of similar weights be able to produce similar results? In the demostration I saw, if you turned off the vacuum, and held the top piece, the bottom piece fell off.
Juan
I had always wondered what who came up with that misapplied demonstration...
It should have been obvious considering it's effectiveness at proving nothing. </font>[/QUOTE]
Juan
Originally posted by Dukk:
</font><blockquote>quote:</font><hr />
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class).
</font><blockquote>quote:</font><hr />
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class).
It should have been obvious considering it's effectiveness at proving nothing. </font>[/QUOTE]
05-25-2005, 04:54 PM
#28
1000 Watt CAFz'r
Join Date: Aug 2001
Posts: 1,770
i first seen it when i went to a router magic seminar an seen a vacumn pump attached to piece of plexi which had foam around the edge
which was then sucked via the pump to a piece of mdf
the vacumn from the pump would secure the mdf to the table from it leaking through the mdf
makes you stand back and go wtf
which was then sucked via the pump to a piece of mdf
the vacumn from the pump would secure the mdf to the table from it leaking through the mdf
makes you stand back and go wtf
05-25-2005, 08:58 PM
#29
500 Watt CAFz'r
Join Date: Apr 2004
Posts: 756
Ya, I'm really happy with it. Standing next to it, you can hear that not as much sound is escaping the box, you can stick your hand on the box and feel that it doesn't hop around or flex as much anymore too. And I used it as a cutting board and you can't even tell I dragged a cardboard cutter across it a few times... Had to cut a piece or two off around the baffle board edges, and ya, it's damn tough stuff.
Just wish I coulda metered the box beforehand for a before & after comparison
When I made my port plug, I had to sand down the lip that was there, and it seemed to sand alright. It did get hot quick though (using 60 grit), had to stop sanding & let it cool a couple times. It never got gucky like you would expect when it gets heated. If you had to sand an entire surface rather than a lip, I'm sure you could do it, just hafta go slower than normal.
He told me that it dries in 3 to 5 seconds, which is why you will never see a run like you do in sloppy paint jobs...
Just wish I coulda metered the box beforehand for a before & after comparison
When I made my port plug, I had to sand down the lip that was there, and it seemed to sand alright. It did get hot quick though (using 60 grit), had to stop sanding & let it cool a couple times. It never got gucky like you would expect when it gets heated. If you had to sand an entire surface rather than a lip, I'm sure you could do it, just hafta go slower than normal.
He told me that it dries in 3 to 5 seconds, which is why you will never see a run like you do in sloppy paint jobs...
05-26-2005, 12:41 PM
#30
Guest
Posts: n/a
Originally posted by OldOneEye:
I'm confused, would two pieces of non-porous products of similar weights be able to produce similar results? In the demostration I saw, if you turned off the vacuum, and held the top piece, the bottom piece fell off.
Juan
</font><blockquote>quote:</font><hr />Originally posted by Dukk:
</font><blockquote>quote:</font><hr />
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class).
I'm confused, would two pieces of non-porous products of similar weights be able to produce similar results? In the demostration I saw, if you turned off the vacuum, and held the top piece, the bottom piece fell off.
Juan
</font><blockquote>quote:</font><hr />Originally posted by Dukk:
</font><blockquote>quote:</font><hr />
Now, as for my test (two sheets of MDF, one on top of the other, using a vacuum hose hooked up to the top one), its something the Derek Lee showed me back in the day at Mobile Dynamics (Dave at Gemsem was in my class).
It should have been obvious considering it's effectiveness at proving nothing. </font>[/QUOTE]</font>[/QUOTE]My point Juan is that the demonstration doesn't prove anything other than that yes indeedy you can pull air through MDF with a vacuum pump or shop vac.
That doesn't seem to have any application to audio and it certainly does not prove or disprove anything having to do with woofer cabinets. [img]graemlins/dunno.gif[/img]
It's a smoke and light show that serves no purpose.
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