posted
I just changed my setup from 2 eD 13kv2's in a 1.6cft enclosure to a 3cft vented box tuned to 30hz. I had the sealed enclosure forward firing into the rear seat pass through in my 05 Altima and have tried the new vented box the same way and I am not hearing any improvement in output.
I also tried the vented enclosure rear firing and it is even quieter. One thing I did notice when I had both the sealed and vented enclosure forward firing was if I opened the trunk there is a TREMENDOUS change in output. This is the kind of output I am looking for but I can't drive around with my trunk open
I was wondering if I may be having some sort of cancellation with the box firing forward. I took out my rear deck 6x9's and so I have some large openings into the trunk. Would it help if I sealed these openings?
I have thought about maybe keeping the 6 x 9 spots opened and try upfiring the box.
I am just really frustrated. I spent alot of time building the new vented box after peopel telling me there would be a lareg change in output and I am just not seeing it.
Here is a link to my sealed box facing towards the back, btu usually it is turned around and firing forward. As you can see it is a snug fit in the opening it sits in. I made the vented box to the same outer dimensions but just deeper. The other links are to the vented box without the top on.
posted
thats a very nice box, as for output being so quiet, i have no idea. what are they tuned to? what type of power? there is almost no reason for the subs to get louder if firing forward with the trunk opening. are you sure your subs are not wired out of phase?
Posts: 385 | From: Hattiesburg Mississippi | Registered: Jan 2006
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posted
actually there is a reason the subs would get louder with the trunk open its called back wave and front wave canceling each other..remember eddie runner guys, he wrote a full tutorial on this and said that in a trunk car the best place for the box to be was most often about 6 to 8 inches from the back of the trunk with the subs pointing at the tail lights. Since this usually isn't practical, consider sealing around the front of the box, keeping it firing forward, so that there is no leakage of air between the front of the box and the back of the box, if you do this, your opening/closing the trunk will make no difference assuming you did it right. If you need any more details you can hit me up on aim sqlbassmachine or just pm me.
-------------------- life is a dance you learn as you go, sometimes you lead, sometimes you follow. Posts: 1391 | From: southern cali | Registered: Oct 2004
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quote:Originally posted by mike hatt: actually there is a reason the subs would get louder with the trunk open its called back wave and front wave canceling each other..remember eddie runner guys, he wrote a full tutorial on this and said that in a trunk car the best place for the box to be was most often about 6 to 8 inches from the back of the trunk with the subs pointing at the tail lights. Since this usually isn't practical, consider sealing around the front of the box, keeping it firing forward, so that there is no leakage of air between the front of the box and the back of the box, if you do this, your opening/closing the trunk will make no difference assuming you did it right. If you need any more details you can hit me up on aim sqlbassmachine or just pm me.
Thanks for the advice, would you feel that closing the 6 x 9 openigns off would help with isolating this back wave? Also for the previous poster I have the box tuned to ~30hz and am powering the subs with an eD 8.1 at a 2ohm load which ~ 900wrms
Posts: 10 | From: Bloomington, Illinois | Registered: Aug 2005
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posted
what you'd want to do to seal it is build a second baffle that is shaped like your trunk opening into the back seat, then seal it in there with expanding phoam, leaving holes for sub and port to come on through, and yes you'd want to seal up the six by nine holes, you want your trunk and cabin as isolated from each other as is humanly possible, expanding foam is your friend.
-------------------- life is a dance you learn as you go, sometimes you lead, sometimes you follow. Posts: 1391 | From: southern cali | Registered: Oct 2004
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posted
it may not be a huge deal if you have a NEW car to not use expanding foam as it it hard to get off if you sell the car. just make sure u cut everything perfectly and as close to the trunk shape as possible. weather stripping is another idea.
Posts: 385 | From: Hattiesburg Mississippi | Registered: Jan 2006
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posted
good point..forgot its a damn near new car.
-------------------- life is a dance you learn as you go, sometimes you lead, sometimes you follow. Posts: 1391 | From: southern cali | Registered: Oct 2004
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quote:Originally posted by mike hatt: good point..forgot its a damn near new car.
Yeah with it being a new car that may not work. But I am going to try to put a secondary baffle in that fills the trunk around the box and I can get some of that Tempurpedic foam stuff pretty cheap and will try to use that to fill in behind the baffle and the trunk and then use a dense weatherstrip for around the box.
What do you guys think about Up Firing and aiming them towards the 6 x 9 opening and then lining the box with a dampening layer to help decrease secodnary waves from the box.
Posts: 10 | From: Bloomington, Illinois | Registered: Aug 2005
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quote:Originally posted by wantlotsofbass: "2 eD 13kv2's in a 1.6cft enclosure to a 3cft vented box tuned to 30hz"
Are you sure that the volume coresponds with the ports and such?
Yes I made sure to make the box large enough to allow for the displacement of the sub and the port to still give me 1.5cft per sub. It actually came out to 1.51cft per sub Posts: 10 | From: Bloomington, Illinois | Registered: Aug 2005
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posted
start off with some tape to temporarily seal it and see if it helps. if it does then cancellation is the culprit. also slide the box to the back of the trunk firing rear just to try it out. My ported box has a sweet spot a bit less than a foot away from the rear. any closer or farther and i lose some db.
posted
try tuning higher, lose the portion of the port after the 90 degree bend...
for a tuning of 30hz your box needs to be MUCH bigger for it to be effective...the frequency of a 1.5cuft box is much higher than 30hz...probably around 42-47hz...you tune the port to the box NOT the sub to the box
you can put a fat girl in a g-string...but something about it just isnt right...
Posts: 378 | Registered: May 2001
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posted
It is 1.5 cft per sub, and I went with specs that the manufacturer gave me. And why should I lose the portionof the port after the 90 degree bend? That is the center divider that separates each individual port for each sub
Posts: 10 | From: Bloomington, Illinois | Registered: Aug 2005
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posted
if the manufacturer tells you to build a 2.5-4 cuft box to tune to 30hz....how many people will find it feasible?...sales first performance later
the 90 degree bend reduces your airflow efficiency due to the 90 degree bend...can you take a corner in your car faster with a gradual or a sharp 'curve?
you can keep the middle divider, just lose the part of the port after the bend...this will tune you in the 40hz-47hz range, where things start to get loud...
'most' subs can play below tuning in daily drivers just fine as long as the air velocity of the port coincides with the box resonance...
i'd run the height of the port the full height of the box, the way you have your port isnt very efficient...when the air is flowing into and out it gets caught on the upper part...the entire mass of air inside the box should flow freely without getting caught in any 'stagnant zones' eg; the area above the top edge of the port...
your box is to small to be tuning to 30hz...if you have a basic program like winsisd, see what the f3(?...forgot actual terminology) of a 1.5 cuft box is... Posts: 378 | Registered: May 2001
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