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Ok I Need some Box Building and Stereo Help

Discussion in 'Audio' started by zcarczar, Mar 5, 2002.

  1. zcarczar

    zcarczar 1/2 ton status

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    Ok here is my Problem, i went over my budget when i bought my subs, and i know im going to need a killer amp to run them also, but back to the problem, i need a box since my dad (the bank) wont allow me to spend too much more on a stereo unless it for an amp and wires and i need a box , My setup for subs is 2 Audiobahn alum12x's, the from the dimensions website are Depth; 5 5/8 Inch Hole; 11 1/8 Inch Diameter; 12 3/4 Inch, i would like to be able to run them in the same box and mount my amp on the box so when i need room i can just unhook the amp and take it all out together, ive looked at the possibility of running a box over the wheel wells, but ruled that our since i have a spare tire on the right and a 4x10 speaker opening on both the left and the right, If i recall right the subs call for .88cf for each sub in a sealed box(I will check on this), i also found a custom box made for these subs and the external dimensions would be 14" h X 14 1/2" bd X 9" td X 27 1/4" w, i would like to copy this, but i would need to know what kind of wood to use, i was thinking of using MDF since that is what that box is made out of, but what thickness would i use? Im all new to this as you can probably tell, i also am curious about capacitators, since i will be running a fairly high wattage with the speakers, ive read that 1 farad per 1000 watts is suffiecent, is this true? or should i run more so i dont blow a battery like my friend did or get blinking lights? also what brand cable should i use? i was thinking monster cable because it looks like quality stuff and i have seen it used many times in system's in cars
    Thanks ahead of time for the help, it will be much appreciated!
    Jason

    BTW- sorry its long and im only 16
     
  2. Prembird

    Prembird 1/2 ton status

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    <blockquote><font class="small">In reply to:</font><hr>

    i would like to be able to run them in the same box and mount my amp on the box so when i need room i can just unhook the amp and take it all out together

    <hr></blockquote>

    You can do it this way pretty easy... When you make your connections you can use a junction box type of thing to make it easier on you.. You can find them at places like radio shack and what not.. Also mounting the amp to the box will not hurt anything.. But you must remember that by doing that it will make it easier for someone if they want to steal your stuff...

    <blockquote><font class="small">In reply to:</font><hr>

    i would need to know what kind of wood to use, i was thinking of using MDF since that is what that box is made out of, but what thickness would i use

    <hr></blockquote>

    mdf if what most boxes out there are made of... There is also wood called meadite (spelling?) that is the same thing just alot more densor and cost just a little more (i recommend using medite) As for how thick to use... common rule is for 10's or smaller use 1/2 in. for 12's use 3/4 in. and for 15's use 1 in. wood...

    <blockquote><font class="small">In reply to:</font><hr>

    i also am curious about capacitators

    <hr></blockquote>

    Depending on how much power you plain on pushing you might not need a cap at all.... i recommend that you install everything and then see if you will need it.. and yes what you heard was right.. for about every 1000 watts you should have a 1 farad cap... but from 0-1000 watts doesnt mean you will need to have a cap...

    <blockquote><font class="small">In reply to:</font><hr>

    also what brand cable should i use? i was thinking monster cable because it looks like quality stuff and i have seen it used many times in system's in cars

    <hr></blockquote>

    I have installed alot of stereos using moster cable.. It seems to be pretty good quality stuff and its readily available.. Doesnt cost an arm and a leg.. Also I have heard that stinger brand stuff isnt that bad but i dont know about them since i havent used there stuff before... I am using Rockford Fosgate wires in mine right now... But to answer your question.. Yes moster cable is good quality..

    Hope this helps.. Feel free to ask away if you have any more questions.. There are alot of use here that are more then willing to help you out...
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Zcar,

    I hope your dad is a real understanding guy.....the unfortunate truth is that you probably still have quite a bit of money to spend....

    MDF for sub cabinets
    Heavy gauge power wire from battery to amp (including inline fuse)
    Heavy gauge ground wire from amp to chassis ground
    AMP - Sounds like you're going to need something pretty stout for the subs you've chosen.
    Stiffening capacitor - Depending on your amps power rating
    Speaker wire for subs
    RCA cables to run from the deck to the amp
    Carpeting for sub box / Spray adhesive
    Grille covers to protect speakers.
    ...etc.

    It's amazing how fast the "little stuff" adds up sometimes. That's why it's important to plan the entire system out first and figure out how much $$$ you've got to spend. As always, modestly priced equipment installed WELL.....will sound better than EXPENSIVE equipment that has been cobbled-together poorly because the money ran out....

    Something to think about. If you've already blown your budget with just the subs....maybe you should re-evealuate your plan and trade them in for something more cost-effective so you can still afford everything else you'll need.

    Just another set of opinions from someone who's definitely "been there and done that"....when it comes to going over-budget!!! /forums/images/icons/laugh.gif
     
  4. zcarczar

    zcarczar 1/2 ton status

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    Ok i think ive decided what i am going to do, my dad was wanting me last night to add up the total i have spent on my car so i didnt get in over my head and i do have enough left in my budget to get what i need for the system, like an amp, caps, etc. Its just going to make me owe may dad a little more,
    Ok i think i have the Boxes worked out, I was sketching some possible designs in class today,
    These are the external dimensions for a box using 3/4" MDF as wood one possibility is 33.5"w x 17.5"h x 9.5" d that one is for 2 subs,
    This is for one sub 17.5"w x 17.5"h x 9.5"d, if my calculations were correct each of the boxes should be .88cf per sub, but i wasnt sure if that was without the sub in there, but i will try and get some more info later
    Thanks for the replies
    Jason
     
  5. zcarczar

    zcarczar 1/2 ton status

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    Anyone? Still looking for box ideas
     
  6. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Zcar,

    What are you looking for.....? It sounds like you already have the box design figured out....

    Is .88 Cu/Ft per speaker within the manufacturers recommeded cabinet volumes?
     
  7. Rebel-Rider

    Rebel-Rider 1/2 ton status

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    calculations wrong

    sorry to burst your bubble but 17.5 x 17.5 x 9.5

    is not .88 cubic feet, to do the math wright do 17.5 x17.5 x9.5 which will give you 2909.375 and then divide that bye 1728 (12x12x12) which will give you a total of 1.68 cubic fett
    so here it is again 17.5 x17.5x 9.5=2909.375/1728=1.68
     
  8. zcarczar

    zcarczar 1/2 ton status

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    Re: calculations wrong

    I know Rebel Rider, that is a box for 2 subs, Greg .88 cft is within the manufacturer's specs for a sealed box like i am going to run, but i was looking a the specs for the sub box reccomendations and it was .88 cubic feet without the air displaced by the sub which is .18 cubic feet per sub, by the time i subtract that from the total box it is to small so i geuss it is still back to the drawing board, also is there anyway i can make it so that i can actually anchor by boxes into my truck using locks or something like that so in the summer when the top is off my stuff wont get stolen out the back at school or work? i was thinking of using an eyelet bolt with a cable and a bike lock and run that through my spare tire holder on the side and go through the wheel so that is help in there also, sounds like its feasible but would like a few opinions, thanks for the responses
     
  9. Prembird

    Prembird 1/2 ton status

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    Re: calculations wrong

    well there are ways to trick the sub into thinking there is more room inside a box then there really is.. Use polly fill or something along that line... I dont remember exactly how much you can trick the sub but you might be able to get your .18 out of it that way... Also if you add just a half inch to the top of the box then that should just about take care of it... or a half in to each side or front... along with polly fill you shouldnt have a problem with space at all..
     
  10. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: calculations wrong

    zcar,

    Hey do me one favor.....add a little more info to your profile! /forums/images/icons/smile.gif I'm feeling a little weird not having at least a first name to call you by, and I'd like to know what type/year of Blazer you have. That might be good info for the rest of the guys trying to help you too.....

    OK, enough about that.

    Prem is right about the polyfill....you can get it at most fabric stores or crafts-type places. Basically it's "pillow stuffing", but it can be used to create an apparent "larger" box. If I recall correctly.....stuffing the box with polyfill can get you maybe an extra 10-15% volume. It's not "magical" stuff, it won't add 100% more airspace or anything like that.....but it can get you just that "little extra" when you need it.

    Sealed boxes (like what you've designed) tend to be a bit more forgiving about the box being slightly too small or large....a ported box would "punish" you with really BAD sound.

    The thing to remember about the box size, is that if you are building box on the "small side" of the manufacturer's spec, the speaker will have to work harder to produce the LOW notes and to hit the high SPL values. The small amount of air in the box increases the speakers "mechanical damping"...so it's harder for the sub to get full excursion and play LOW....

    If you put that same speaker in a box that was on the "high side" of the manufacturers recommended sizes....it would sound more relaxed....it could move more easily, and would hit the lower notes with less difficulty. I know, there are always tradeoffs (box size vs sound quality) and you may not have the room available to build the BIG box. I just wanted you to understand that there are benefits, if you can work it out.

    As far as securing the subs......that's ALWAYS a good idea! For safety of course, and because if the cabinet is firmly connected to the floor, it can "couple" it's energy into the truck better.......are you looking for a way to keep these things "removeable" or do you want them permanently bolted in?
     
  11. zcarczar

    zcarczar 1/2 ton status

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    Re: calculations wrong

    The trucks specs are my signature
    OK, how would i attach them to the floor without having bolts that stick out of the floor when the subs are out? I havent really thought this one out yet, i will run the specs with the sub boxes expanded by about a half inch to maybe see if i can get the box a little bigger
    What about water proofing? i have seen that people have been running thompson's water sealer or something like that to keep water out, so i am assuming that this does work with MDF or medite. Hopefully this weekend i can go the wood and screws and start on the boxes
    Thanks
     
  12. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: calculations wrong

    Jason,

    If you want the boxes to be removeable, part of the trick will be to find a way to built brackets that can "wedge" underneath existing mounts......like the rear seat brackets or spare tire carrier. That way, you're not drilling a bunch of new holes, and when the box is OUT, everything looks normal. If you can wedge it in place somehow.....you will only need a couple of fasteners to keep the rest of the box from shifting around.

    As far as a sealer.....MDF can be treated with standard polyurethane sealer.....it's a good idea if you think it might get wet. I'd do both the inside and outside of the box.....since humidity will eventually allow moisture to get inside anyway. It doesn't take that long to do it, so it's good "insurance".....also don't forget when the box is finished, to seal all the internal seams with silicone caulking.....you don't want ANY air leaks. I've posted LOTS of photos of my subwoofer boxes being built so you could look at those for ideas if you want. They're in my .sig also

    Hope that helps!
     
  13. Prembird

    Prembird 1/2 ton status

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    Re: calculations wrong

    Just to add a little more here... Water sealing a box is a good idea but please keep in mind that the sub will be exposed to the elements even if you water seal the box. Some subs out there are still made from a paper composite and just a little water on those will distroy them...
    Just wanted to add that...
     
  14. zcarczar

    zcarczar 1/2 ton status

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    Re: calculations wrong

    Alright cool, ill take a look this weeekend at the various stuff that i will need, I'll take a look at the back of my car when i go and see how its doin at the body shop, I think my subs cone is made out of Aluminum so that should add to the durability a bit, also is there anyway you guys recommend to mounting the amp inside the side panel so it would be harder to steal if someone was to steal it Well i geuss i will check it out tommorrow
    Thanks
     
  15. zcarczar

    zcarczar 1/2 ton status

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    Amps

    Alright i got my subs and wood today, i got the boxes all figured out, ive managed to get 1.01 cubic feet per sub in a sealed box which is in the manufacturer specs, but the next thing i need is an amp, the local stereo shop by my house has a memphis amp that is 525 watts RMS x 1 channel, is this ok to run 2 12" subs with 2 6 ohm voice coils each?
    Thanks
     

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