Down Fire?
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Pro
Joined: Aug 2005
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From: Fort Worth TX
Down Fire?
Anyone ever try down firing thier sub in the car before?
It seems to work really well with home audio, and based on its specs my sub is a good canidate. I may try this with a sealed enclosure and see what I get.
What do ya think?
It seems to work really well with home audio, and based on its specs my sub is a good canidate. I may try this with a sealed enclosure and see what I get.
What do ya think?
Melting Slicks
Joined: Dec 2004
Posts: 2,394
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From: Bay Area CA
You could certainly build a box to do it, but you need to vent the air that the sub pushes somehow, which means you could not build a "press fit" or any other flush mount style box. All down firing subs have either a stand or legs of some sort to keep the woofer off of the ground (obviously for excursion) but it also allows the air to be moved creating your bass. Some high end down firing home units will have a port much like a bandpass box for the car to direct the air and allow corner loading.
Fej
Fej
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Joined: Aug 2005
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From: Fort Worth TX
OK so I have a single 12"
I make say a 12d X 18w X 6h sealed enclosure. Mount 2" legs on it now im at 8" high.
That should be more than enough room for excursion yeah?
NOTE: these are not exact specs just rough estmates. Of course I have to make the 1.25 cu ft box to match the sub specs. Im just wondering how it will sound. And I need a project. My builder is still not done with the engine.
I make say a 12d X 18w X 6h sealed enclosure. Mount 2" legs on it now im at 8" high.
That should be more than enough room for excursion yeah?
NOTE: these are not exact specs just rough estmates. Of course I have to make the 1.25 cu ft box to match the sub specs. Im just wondering how it will sound. And I need a project. My builder is still not done with the engine.
Melting Slicks
Joined: Dec 2004
Posts: 2,394
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From: Bay Area CA
2" legs would be plenty for excursion, and as I mentioned earlier you could build a "port" (well in reality a vent) to guide the air to your desired exit, or just simply allow space for the air to move from underneath the box to outside. This is far beyond my technical knowledge, but there may be some issues with wave cancellation and the air moved from the sub (and its soundwaves) colliding with itself as it moves out from the box. Then again I may just be on crack 
These issues don't really arise with home apps as the "space" that the speaker functions in is much larger and the waves have much less "bounce" to them. Interesting idea though.
Fej
These issues don't really arise with home apps as the "space" that the speaker functions in is much larger and the waves have much less "bounce" to them. Interesting idea though.
Fej
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
a friend of mine had a 15" sub in a 7th order band pass box (I think it was 7th order, it's been a LONG time).
However, the box was HUGE, it was ported, and the sub was recessed into the top with a lid that was vented. So the lid created a top load (much like a down firing sub). It was an Orion sub and amp. Damn, that thing HIT and hit hard.
However, the box was HUGE, it was ported, and the sub was recessed into the top with a lid that was vented. So the lid created a top load (much like a down firing sub). It was an Orion sub and amp. Damn, that thing HIT and hit hard.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
yes, you can downfire the sub but as mentioned you just need to allow room for airmovement and driver excursion. Usually this is done to hide the sub for a more hidden type of installation or to protect the sub from damage if the area the subbox is in would be used for other cargo, packages, etc.
reflection of the sound wave back to the speaker is always somewhat of an issue but shouldn't be enough of a concern for you to worry about.
One effect of firing directly into the floor though is usually an increase in the total output as the soundwave "loads" against the solid surface (in this case the floor). It would be same if it was standing up and firing directly into a wall. All this means for you mostly though is that you may have to turn the gain of the sub amp down slightly to compensate for it so the bass isn't overwhelming.
Oh....... you may also want to consider a sound damping material such as on the floor to help control some of that excess soundwave energy.
reflection of the sound wave back to the speaker is always somewhat of an issue but shouldn't be enough of a concern for you to worry about.
One effect of firing directly into the floor though is usually an increase in the total output as the soundwave "loads" against the solid surface (in this case the floor). It would be same if it was standing up and firing directly into a wall. All this means for you mostly though is that you may have to turn the gain of the sub amp down slightly to compensate for it so the bass isn't overwhelming.
Oh....... you may also want to consider a sound damping material such as on the floor to help control some of that excess soundwave energy.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by bogus
However, the box was HUGE, it was ported, and the sub was recessed into the top with a lid that was vented. So the lid created a top load (much like a down firing sub). It was an Orion sub and amp. Damn, that thing HIT and hit hard.
If built properly they can sound very good and I've done a number of excellent ported boxes, especially bandpass and isobaratic bandpass boxes but they better be done correctly because there is VERY little margin for error - you get the chamber sizes wrong and/or port size wrong it goes from sounding great to sounding like pure crap. Ported boxes do have the advantage if you are looking for this or need it of typically producing more output meaning a higher db level.
Sealed enclosures on the other hand are smaller, more forgiving if the air volume is a bit off, and have better power handing capabilities.
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Joined: Aug 2005
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From: Fort Worth TX
Everything is sound deadened, and G2G. It is all a matter of box design and build now.
The bass traveling through the car body is what I was looking for. Its plenty loud in what I have, but you dont feel it like with other systems Ive had. My home sys will rattle the pics of the neighbors walls.
That got me to thinking. I bet I can make my car sub do that.....
The bass traveling through the car body is what I was looking for. Its plenty loud in what I have, but you dont feel it like with other systems Ive had. My home sys will rattle the pics of the neighbors walls.
That got me to thinking. I bet I can make my car sub do that.....
