Home Theater Subwoofer Enclosure

[budahbuddy803 10+ year member]

I am thinking about building a box for my 15" IDQv2d4 for my home theater. I am new to home theater if you didnt already know by my dorm room setup that everyone laughed at. I want to go ported but I am not sure how low to tune. It will be playing music, movies, TV, xbox... anything I hook my receiver up to.

It will be powered by my STR-K700 @ 4ohm. Amp says 135watts to the sub. The impedance of all speakers that came with it were 6ohm. I dont know if that is an rms rating or what, but I have been running the subwoofer channel @ 4ohm since I got it and the center/left/right @ 8ohm.

I am not worried about the output, I am more concerned with SQ. I had it in a box ~2.5 @ 37hz just because the sub was already in there and the output was fine and it sounded alright, I just want to tune lower I guess. How low is too low?

CLIFFS: 15"IDQv2 for movies, tv, music, xbox, computer.... how big and what frequency to tune to?

Also, I wouldnt mind doing some sort of bandpass if it would improve the sound. I still just dont know how big and what frequency to tune to.

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[RAM_Designs 5,000+ posts]

5ft^3 tuned to 20hz will get most explosions and such.

 

[budahbuddy803 10+ year member]

Thanks any other suggestions or is that about right on?

 

[stanky1219]

Yeah for HT you need big and tuned as low as possible.

 

[budahbuddy803 10+ year member]

About to do ~5.4 cuft @ ~23hz with 43 sqin of port area.... too big or anything?

 

[schrummy 10+ year member]

im thinking you should try around 70 square inches of port.....

 

[RAM_Designs 5,000+ posts]

im thinking you should try around 70 square inches of port.....

In big, low tuned boxes for HT, a smaller port is perfectly fine since you're normally dealing with less displacement and power than a normal 5ft^3 box for car use. Not to mention lower tuned boxes are less susceptible to have port noise than a higher tuned box of the same port opening.

OP: depending on how much air you plan on moving with that IDQ, anywhere from 25-50in^2 of port is ok for 10-20mm worth of excursion(~.75" to ~1.5" total excursion).

 

[budahbuddy803 10+ year member]

Well, I went with what I said. It is not accurate I know that, but I ran into a problem. On low notes you can hear the sub bottom out i guess. It sounds terrible like I am overpowering the mess out of it, but only on low frequencies. Could too low of tuning or the size of the box make it do that. I am not sending it more than 150rms and have the sub level all the way down.......

The box is big and I made it with 1/2" because its easier to work with and many of reasons actually. I am going to add a few braces because I feel it is not as sturdy as it should be, but what could be the problem here?

Edit: This only happens of course when volume is 50-60/80 which is my loudest listening level, but still.

Edit x2: I think it may be a loose connection on the sub. Ill take it out and see.

Edi x3: Nope, any ideas?

 

[RAM_Designs 5,000+ posts]

Could be lack of bracing, causing the box to resonate with the sub in a certain frequency range.

 

[budahbuddy803 10+ year member]

Well, after messing around with it a little bit more, the box does flex quite a bit. I think that that may have something to do with the subwoofer reacting with the resonating walls, possibly? I used 1/2" because it was a little cheaper and I have not ran too many high power subwoofer systems, when I did i used 3/4", but it was overkill for my 200rms sub stage.

I guess with most any ported 5 cuft box needs 3/4" because this again is no high power setup. I plan on using some left over MDF to brace it as much as I can. Ill get pics up tomorrow or whenever I get around to fixing it.

 

[budahbuddy803 10+ year member]

Could be lack of bracing, causing the box to resonate with the sub in a certain frequency range.

yeah, kind of what I am thinking.

 

[RAM_Designs 5,000+ posts]

yeah, kind of what I am thinking.

If you did it with 5/8 mdf, brace the shit out of it. Those low notes have a lot of force behind them.

 

[budahbuddy803 10+ year member]

If you did it with 5/8 mdf, brace the shit out of it. Those low notes have a lot of force behind them.

Yeah, haha after a few minutes of testing i can tell. Ill do the best I can

 

[solidcrowd 10+ year member]

sonotubeee //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[RAM_Designs 5,000+ posts]

sonotubeee //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Those work great if you don't mind having a big tube in your room somewhere.