What size box would I need for 2 12" Shivas. I want the best sound quality possible. I keep being confused as to what the difference is between the box types. People use terms im not quite used to like low end extension and response. I believe low end extension is just hitting the lower freqs. But response im not sure of. Which type of box would give me the best SQ and what size of that box would I need. Also what is the regular price on that kind of box??
any help would be appreciated. now im thinking of just going with 1 shiva if i got ported to save room and money. thanks please answer all of my questions as they are all importent. thanks again.
Yeah, you wanted the best SQ. A proper sealed box has better sound quality than ported, and also allows the sub to drop lower. The Shiva hits very hard at subsonic levels (below 20 hz) and a ported box will not allow this to happen. A ported will give better low end extension around the tuned frequency, but below that point the subwoofer performs as if it were free air and loses control, and it can damage the sub if you aren't careful. A sealed box can drop to 9hz flat, which is what you need with a Shiva.
how much louder is a ported with shivas and how often do you get below lets say 20-25 hz when using regular music i just want to know if porting is really worth it. it was recomended earlier that i port and tune to 30 hz but now ive heard that sealed is recomended with 2 shivas. i just want to know what to do. please tell me if porting will make them considerably louderor just a little. whats the db difference
Not often, mostly on test tones. Music rarely goes below 30 hz. A ported box is the same as having two subs, because both sides of the sub are used. You'll typically see 3-4 db of gain. The drawbacks are the ability to drop really low and you lose a little tightness, how you build a ported box is what determines the sound quality. A proper ported box will sound nearly as good as the proper sealed, you'll get more output, but lose a little bit of ability below the tuned frequency of the port.
also if im going to make a custom box why not make the box 1.65 cu ft since that is what the sub will think the box is anyway. instead of using polyfill? why wouldnt I just make it the perfect size in the first place?
Polyfill has added benefits than just making the box appear larger, it can dampen the box, so boxes don't sound as "boomy". That's why a lot of manufacturers recommend polyfill, because when used correctly it can reduce resonance in the enclosure, making the sub sound tighter. I prefer to staple polyfill to the box, but some people just leave it loose. It doesn't really matter as long as you get the proper amount in there.
ok here goes im not sure if i have the right subwoofer here but heres the specs of the one i ran.... re 2.9 ohms qms 6.5 qes .40 qts .38 fs 21 vas 151 liters xmax 16.6 mm one way spl 87.3 db 1 watt per one meter 650 watts rms i think they are saying power handling. Ok now if this is your subwoofer i ran it in my program and it seems they are best sealed you would have slightly better qtc at 3.5 cubic ft internal air space but would be slightly worse at 3.0 cubic ft. This is the box sizes i would recommend.
That would be either 6 cubic ft total for 2 12s or 7 cubic ft. You could also slim the box size down with insulation to fool the woofer 1 inche per fiber or 1 lbs polyfill per 10 percent boost in volume approx. Its usually only recommended to boost the volume this way by no more than 20 percent but i heard of people going further.
3.5 per sub or for both subs? Remember that programs like WinISD etc. don't compensate for cabin gain in a vehicle, so you're not going for a response that's flat all the way across. Really, the best thing to do is to aim for the QTC you want, .707 is a good all around QTC to shoot for. A .707 QTC for the Shiva is around 2.1 cu ft, you'll get pretty close to that with a 1.75 cu ft box and 1.75 lbs of polyfill.
i was saying per subwoofer 3.0 to 3.5 cubic feet using win isd. Are my theil small specs i listed not for that shiva woofer he has? I just thought of the fact that in car creates cabin boost right before i saw your post so your right to remind me jonathan. Qtc at 3.0 cubic feet is 2.86 qtc 2.65 qtc 3.5 cubic feet not sure if in car can adjust qtc by that much but i agree its definately possibe it could go below the golden number.
I meant the QTC of the enclosure, not the speaker. The specs you had were right. In the box tab in WinISD, you'll see the QTC below the volume of the enclosure, what you like determines what to shoot for, but .707 is considered the best balance between tightness and bandwidth.
jonathan that qtc i qouted is the box size 3.0 cf. 2.86 qtc 3.5 cf 2.65 qtc that number shows up right under the box size on win isd when i punch those numbers in.
That seems extremely high, I'm getting a .63 QTC for 3.0 cubic foot and a .60 QTC for 3.5 cu ft. The smaller the box is, the higher the QTC of the box, but you're not going to have a box with a 2.86 QTC. Make sure all the sub's parameters are entered correctly.
ok jonathan i checked my numbers again and i did have the qts wrong now im getting 2.52 istead of 2.65 qtc for the 3.5 cf box. I know you must be right but im trying to understand what im doing wrong here. Im using winisd online not the downloaded program. Is that why im getting the wrong number if so please help me understand the right way. I appreciate your following up with me and your patience.
ok i used a different box program and i got what you got jonathan 2.1 cubic feet sealed gives .71 qtc i dont know what im doing wrong with linear team.