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Discussion Starter #1
So I had decided for my next project to build a down firing sub. The main reason for the down firing design was to protect the sub from the 2 year old. A recent post on here talked about the downsides of the down firing. The one I'm concerned with is gravity wearing out the sub over time.

I would prefer front firing anyway. I was thinking of firing it toward the wall with the port facing forward. Would this effect performance? Is there any other way to protect the sub without hindering performance too much?
 

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If you choose to do forward firing these worked well for one of my projects, the holes are small enough that that can't poke a pen or pencile through the grill.
 

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I would prefer front firing anyway. I was thinking of firing it toward the wall with the port facing forward. Would this effect performance? Is there any other way to protect the sub without hindering performance too much?
Downward and rear firing have the benefit of filtering above bandwidth harmonic distortion created by the motion of the cone. If you're concerned about cone sag go rear-firing. There's no reason to forward fire the port if you do so.
 

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One of the major advantages of forward firing, is a matter of exciting room modes, if you rear fire, and you get major peaks, you can turn the sub to side for forward firing, with down firing, you always going to be loading into the border modes, which may or may not be benificial. As of yet from my many experiments, down firing has actually caused less room mode problems than horizontal, but that may just be the acoustics of my room. Sorry, my computer had crashed on me a couple weeks ago and lost all my links, but I'm sure someone can link a room mode calculator to help you better decide what configuration is likely to yield the best results for you.
 

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Discussion Starter #5
Interesting comments guys. Thanks. Decisions, decisions.... I'm thinking a duel design here. Design it where it can be forward or rear firing. If I place the port on the opposite side of the driver I can make it look proper regardless of the direction the driver is facing.

Then again I wouldn't mind the grate. Is it easy remove? Does it snap on and off? I can remove during movies and put back on afterward.
 

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One of the major advantages of forward firing, is a matter of exciting room modes, if you rear fire, and you get major peaks, you can turn the sub to side for forward firing
Within the subwoofer passband radiation is omni-directional and which way either the driver or the port faces makes no difference with respect to room modes. It does make a difference with above bandwidth harmonic distortion. Boundary loading/Allison effect is affected, best results are usually had when the radiating plane is kept as close as possible to the rear wall and floor and as far as possible from the front wall and ceiling.

If I place the port on the opposite side of the driver I can make it look proper regardless of the direction the driver is facing.
How a cab looks should always be secondary to how it sounds.
 

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Discussion Starter #7
Within the subwoofer passband radiation is omni-directional and which way either the driver or the port faces makes no difference with respect to room modes. It does make a difference with above bandwidth harmonic distortion. Boundary loading/Allison effect is affected, best results are usually had when the radiating plane is kept as close as possible to the rear wall and floor and as far as possible from the front wall and ceiling.
That makes since. I'm taking a mini vacation until Monday. This will give me time to draw up some plans and think over a design.

How a cab looks should always be secondary to how it sounds.
Ehhhh....To some extent. I think that's dependent on the person. Regardless of how good it sounds I'm not going to ugly up my room with a nasty looking box. In the same reasoning I'm not going to nasty up the sound regardless of how nice the box looks. I mean, I'm willing to make some sacrifices but, it has to be okay'd through the wife (a.k.a. Boss). It also has to be designed to protect the driver from my 2yr old daughter or she will make sure it sounds AND looks like Poo. : )

Keep in mind this is coming from a hobbyist. I'm not a pro and just recently got into sub building and I love it.
 

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The sag issue with downfiring drivers is really a non issue with most high excursion drivers. I built my first Ava 18 LLT over three years ago and it hasn't lost any impact or performance. What I have noticed as a generality over the years on these forums is that downfiring subs tend to result in achieving a flat in room response more easily.
 
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