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Thread: Sub box Q's (not totally noobish)

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    Variable Bitrate FyreDaug's Avatar
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    Sub box Q's (not totally noobish)

    I need to build a new sub box for my type R 12" sub, the one I have seems too small, it doesnt sound quite right, doenst quite like the lows like Ive heard some Type R's sound like. Currently its a 1.75ft^3 @ 45hz (I think... thats what I was told anyways and it seems right) I am thinking of going to 2.25-2.5ft^3 @ 32-35hz. I know a guy who works at Audio Express and theyve got some good tuning software for dimensions and stuff, so he can help me out with that.

    What would happen if I went with a box too big?
    And, should I coat the inside of the box with sound deadening material? Ive got quite a bit of b-quiet left. What would it sound like? Would it do anything?

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    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    a bigger box will give you lower frequency extension..... to a point. past that point the box will not offer enough suspension, depending on the driver.... at high power with a box that's to large you will increase the chance of bottoming out the sub or loosing control, which can sound like crap & damage the sub

    I like my boxes on the large side of the scale for sound quality, but especially if your running them at or above max rms, try to stay within limits.... a 1/4' of airspace too much can make the difference between an awsome solid boooooooom & a fluttering fart....

    only use dampening in the box if it's construction is a little less than solid, if you've got a big flat span it won't hurt there, but is unecissary for the most part if the box is constructed properly, your better of bracing anything you feel is going to resonate than dampening it, because dampening will do nothing for flexing

    if the box is to big you can always fill it with extra bracing.... complicated shapes are best built on the large size because it is difficult to acurately calculate total dimmensions before build, it is always easier to take some airspace away than it is to add airspace... the only way to add is to overstuff with polly foam, which can make the box appear up to 10% larger to the sub, taking away airspace is always easier

    the best analogy I can give of box size is picture a mountainbike tire riding down steps... the steps are the bass hits..... very high air pressure in the tire will give a stiff hard quick shot....it is safe though in as far as damage is concerned..... this is the equivelent of a small box... punchy bass with less low extention

    now picture the tires dropped to like 25-30psi...... now she rides down the steps alot less punchy... smoother if you will.... this is the equivlent of a large box.... smoother bass, less punchy & even low bass extention... problem is if the pressure is to low(box to large) then you may smash the rim into the stairs on a big hit(bottom the sub if you didn't get that yet)

    to be safe run the box a little small... for best results run the box larger, but you should mesure the box after it's built & if it is larger than manufactures specs call for, reduce it till it's within tolerances, if you have a good ear you will be able to tell if the box is to large by the subs response....

    are you doing ported or sealed?

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    Variable Bitrate FyreDaug's Avatar
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    Ported. The one I have is ported and the one I build will be aswell. I want a lower tune, because like I said the lows arent as crisp, Im not liking the sound of my bass. It's loud and itll give you a head ache pretty quick at high volumes, but I wish it would be more crisp. Ive got the xover at 70hz, I play between 60-80 sometimes, but typically 70

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    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    ported can increase spl output, but the frequency it winds up being ported to (tuned to)can be difficult to control... a ported box that is "off" by a little will sound much worse than a sealed box that is off by a little.... to do a real good ported box you obviously will need a computer program to design.... & you will be limited in the funky shapes youy may need as they can be impossible to acurately calculate...... try sealing your ports... if the bass sounds better then your box is off...... ports can be an awsome thing, but they also cause a lot more trouble than they cure sometimes......

    in my opinion a sealed box is less hit & miss, not to mention MUCH more liner in its response... much more "musical" rather than show off boomy..... even a properly built properly designed box can need some port experimenting to fine tune.... both length & diameter are the main concerns, but shape, origin of port... orientation to the side/back walls...edge design of opening... there are alot of variables with ports, if box size is not right & ports are not right you can wind up with something that sounds like ****.....

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    Variable Bitrate FyreDaug's Avatar
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    If I went with a sealed box (I'll try sealing the port tonight see how it sounds) I know Id have a flatter response (which I do like) but would it still hit as hard when I need it to? I plan on upgrading to a bigger 400w amp down the road when I get money, still running an RF 200@2

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    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    if the box sounds better overall sealed you will not have the narrow banded bass boost that a good port provides, you didn't have that to begin with though...... what I do is add a boost at whatever frequency sounds best through equalization..... an extra 3-4db at say 45htz might wake up your bass nicely..... some setups may like the boost closer to 60htz.... there are to many variables, but equalization + power + correct sealed box =

    to try & get a port to do the same thing can be tricky.....I'd rather have a little more amp & a sealed box. if you really want to smile when you listen to your bass grab an audiocontrol epicenter or one of the few knock-offs of it...... I love my epicenter... but the better your bass is the less you will have to use it.

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    sealed boxes also actually have more low frequency extension than ported boxes. If you model one up, youll see that the sealed box rolloff is a 6 dB slope, and the ported box is a 12 dB slope.

    chances are, you are only looking at a dB or two of gain anyways from ported.

    combine that with the larger passband of useable frequencies, and the choice is clear!

    now, this isnt to say sealed is better in every way! as an example, you might be giving up that extra two dB at 30 Hz just to get that rolloff extension down to 25 or 22 or wherever the sub gives out.

    but if you really want that presence down there, I think a sealed box might just be what you need

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    btw turbo, ever go ghetto blasting in your car in a downtown area, middle of the day with the epicenter turned up playing country music with a "rap" bassline?



    especially funny in hick areas

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    Constant Bitrate accentsound's Avatar
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    Where is the sub located? in the trunk, cargo area, behind the seat in a hatchback?

    Where the sub is will have a huge impact on how it sounds.

    Boxes in a sealed trunk will always only sound "So So Good" it is the environment and nothing much can be done about it.

    Also a critical factor is getting the box Sealed. NO air leaks what so ever. The box can not bleed any air from the seams or around the driver. This is equally important for vented boxes.

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    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    a sub in a sealed trunk is a challenge, you HAVE to get the bass into the car somehow.... I did a caddy once with a 10" eclipse sub in each qtr panel run off a ppi art 2150....opened the deck up fully..... the bass transfer was increadable.... NOBODY believed it was only 2 10's when they heard it.... sounded like at least a pair of 15's.... if I didn't fully open up the deck though it would have sounded like ****

    I try not to blast bass on the streets.....it's hard not to, but I don't want to look like some jerk off kid... I LOVE to blast it on the hwy though....


    country music???what's that???????

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