Does the port area rule of thumb apply to home theater subs?

[bubbagumper6]

I'm going to be building a small 3 cube box for a 12" sub and I'm just wondering if a 4" flared aero will be enough?

[hispls]

I think the key is displacement of the sub. Many home audio specific or favorite drivers are high efficiency/low mass/low x-max so they can get away with less area. Also it's not like you're tuning for a 30db peak at 50hz in your living room either so I'd just plan around enough so that it can handle displacement without chuffing or becoming a leaky sealed box.

[bubbagumper6]

Bump this back up, the sub I'm using is this one (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-464). So would a 4" Flared Aero be enough for a 3 cubic foot box?

[loud-n-low]

what tuning?

[bubbagumper6]

25hz

[loud-n-low]

I would suggest firing the sub foward,and have the port firing back(like hsu subs and svs) I talked to hsu the other day and they say they use 4" ports vs 3" I would personaly tune at 20hz, use 2 ports,and plug one to change tuning if you wanted

[Jh8909]

your neighbors not gonna like this lol

[bubbagumper6]

I would suggest firing the sub foward,and have the port firing back(like hsu subs and svs) I talked to hsu the other day and they say they use 4" ports vs 3" I would personaly tune at 20hz

Well I was planning on firing the both the sub and port forward, what would be wrong with that? And I modeled the sub in WinISD, 25hz modeled better than 20hz.

[bubbagumper6]

your neighbors not gonna like this lol

lol, I'm hoping that by building the sub enclosure I can put it right next to my chair, so it can be turned down but still give me some bass...

[Jh8909]

word. lol

[loud-n-low]

you would get more output from port facing back if you corner load it..bass could get a little boomy,maybe not.Also firing port back would minimize any port noise vs firing foward

[bubbagumper6]

you would get more output from port facing back if you corner load it..bass could get a little boomy,maybe not.Also firing port back would minimize any port noise vs firing foward

I don't want that right now, lol. That's what I'm trying to get away from. Corner load = my neighbor's walls vibrating

Why would firing to the back affect the port noise? Simply because it would be firing away from me so I wouldn't hear it as much? What about firing the port down?

[loud-n-low]

firing down would reduce almost all noise,and **** off the downstairs people if you have any. Mine fires down, no noise at all. im looking to fire back for more output

[bubbagumper6]

firing down would reduce almost all noise,and **** off the downstairs people if you have any. Mine fires down, no noise at all. im looking to fire back for more output

Bottom floor FTW :)

I'm not looking for huge amounts of output, mainly SQ, I don't want to shake the walls (and obviously can't right now). The only thing I don't like about down firing is that with a 4" port, the box would have to have at least 2" of clearance at the bottom right? Not as easy to move around too and I have to worry about standoffs or legs, w/e...

[loud-n-low]

yes,you would have to elevate it if firing down. If you do sub and port firing foward,I suggested tuning lower to avoid peaky bass,and for flatter response.

[bubbagumper6]

yes,you would have to elevate it if firing down. If you do sub and port firing foward,I suggested tuning lower to avoid peaky bass,and for flatter response.

Yeah when I modeled it, tuning to 20hz instead of 25hz seemed to get me a little bit lower, but sacrificed a good bit of output on the main peak, but I suppose for an SQ HT setup I wouldn't really want any kind of peak...

[loud-n-low]

Yeah when I modeled it, tuning to 20hz instead of 25hz seemed to get me a little bit lower, but sacrificed a good bit of output on the main peak, but I suppose for an SQ HT setup I wouldn't really want any kind of peak...

exactly. could try it sealed first too

[bubbagumper6]

exactly. could try it sealed first too

Here's what I'm looking at for ported, sealed produced a horrible looking graph, it wouldn't get near as low, and was only at 0db until like 100hz then it started to roll off...

http://img412.imageshack.us/img412/5250/winisd.th.jpg (http://img412.imageshack.us/i/winisd.jpg/)

[loud-n-low]

wow, output does seem to go down quite a bit at 20hz. however,where you place the sub in the room will affect peaks even more. Im tuned at 18 hz and love the extreme lows that you feel during movies,also it doesnt get peaky with music (30-45hz). try it at 25hz, if you dont like it you could lengthen the port possibly?

[bubbagumper6]

wow, output does seem to go down quite a bit at 20hz. however,where you place the sub in the room will affect peaks even more. Im tuned at 18 hz and love the extreme lows that you feel during movies,also it doesnt get peaky with music (30-45hz). try it at 25hz, if you dont like it you could lengthen the port possibly?

Yeah I can always modify the port, aero's are easy to play with. Here's a sketchup design of what I've got so far. Obviously sub on the bottom and the port above it.

http://img532.imageshack.us/img532/1793/sketchd.th.jpg (http://img532.imageshack.us/i/sketchd.jpg/)

[bubbagumper6]

wow, output does seem to go down quite a bit at 20hz. however,where you place the sub in the room will affect peaks even more. Im tuned at 18 hz and love the extreme lows that you feel during movies,also it doesnt get peaky with music (30-45hz). try it at 25hz, if you dont like it you could lengthen the port possibly?

holy hell, I just noticed that tuning to 20hz would mean the port would have to be 25" long :crap:

[loud-n-low]

in my opinion, I would have the sub and port both towards the bottom.

[bubbagumper6]

in my opinion, I would have the sub and port both towards the bottom.

I don't really want to downfire the sub simply because I want to be able to see it :D

[loud-n-low]

dual ports ftw! try the 25hz tuning,might be everything you are looking for.

[loud-n-low]

I mean front firing, but closer to the bottom of the baffle

[bubbagumper6]

I mean front firing, but closer to the bottom of the baffle

oh, like side by side at the bottom? I don't think it's wide enough for that...

[loud-n-low]

oh, like side by side at the bottom? I don't think it's wide enough for that...

yup, if they dont fit side by side, I would just try to put the port as low in the baffle as possible

[bubbagumper6]

yup, if they dont fit side by side, I would just try to put the port as low in the baffle as possible

Any reason why?

[loud-n-low]

lowers the chances of unwanted noises from reaching your ears,and all the same reasons subs are to be as close to the floor and not elevated

[bubbagumper6]

lowers the chances of unwanted noises from reaching your ears,and all the same reasons subs are to be as close to the floor and not elevated

Yeah that's a good point...firing the port to the rear seems like a good option, but it eliminates being able to put the enclosure against a wall. I'd have to put it in a corner or have it away from the walls ya know?

[loud-n-low]

Yeah that's a good point...firing the port to the rear seems like a good option, but it eliminates being able to put the enclosure against a wall. I'd have to put it in a corner or have it away from the walls ya know?

why? because the neighbors right?

[bubbagumper6]

why? because the neighbors right?

Yeah, in the long run, corner loading would be fine, but right now that's not an option. I don't want to load anything onto any of my walls...

[loud-n-low]

I would just do port and sub firing forward, have the port as low in the baffle as poss. If you have to have it directly over the sub,try it out,lay the box on the side too. I would just try to have the sub and port both as low in the front baffle as possible. place the sub in a corner,and have the woofer and port firing into the room.

[bubbagumper6]

I would just do port and sub firing forward, have the port as low in the baffle as poss. If you have to have it directly over the sub,try it out,lay the box on the side too. I would just try to have the sub and port both as low in the front baffle as possible. place the sub in a corner,and have the woofer and port firing into the room.

yeah that's not a bad idea either. I just don't want to build this huge box and have the port/woofer placement be a constraint on where I can put it, ya know? Like it HAS to go in a corner, or it CAN'T go against a wall. I want it to be flexible because I'll be moving in August and have no idea what my new living room setup will look like, lol. I'll probably just build it as is, then I can try laying it down, or even downfiring both by propping the box up on some block or something.

Although back to my original question, is a 4" aero enough for 3 cubes? I mean, that's only about 4 square inches per cube...

[loud-n-low]

yeah that's not a bad idea either. I just don't want to build this huge box and have the port/woofer placement be a constraint on where I can put it, ya know? Like it HAS to go in a corner, or it CAN'T go against a wall. I want it to be flexible because I'll be moving in August and have no idea what my new living room setup will look like, lol. I'll probably just build it as is, then I can try laying it down, or even downfiring both by propping the box up on some block or something.

Although back to my original question, is a 4" aero enough for 3 cubes? I mean, that's only about 4 square inches per cube...
no matter what the sub is,(rear port,downfiring etc) people usually pet them in a corner,or against a wall so they are out of the way. a 4"port should be ok,I just usually see dual 3" ports.even dual 4". if you build it and dont like it,could always start over?

[bubbagumper6]

no matter what the sub is,(rear port,downfiring etc) people usually pet them in a corner,or against a wall so they are out of the way. a 4"port should be ok,I just usually see dual 3" ports.even dual 4". if you build it and dont like it,could always start over?

haha, true. I do love building enclosures...