DIY Subwoofer box considerations

Discussion in 'Speakers & Subwoofers' started by Marc*F, Oct 9, 2003.

  1. Marc*F

    Marc*F Stunt Coordinator

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    I am planning to build my own subwoofer box for HT applications and idealy would like the sub to hit as low as possible in a vented box, but my dimensions for the box cannot be any larger than 2.5 cubic feet.

    Considering the box size would I generally be better off with a 10" sub being a larger box relatively or a 12" sub? I know different subs behave differently but would a larger box make more of a difference for low frequency response (20-25hz)?
     
  2. MichaelDDD

    MichaelDDD Supporting Actor

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    Hi Marc*F,

    2.5cf is not a lot of air space for a ported sub, especially a 12" that you're trying to get down to 20Hz.

    The net enclosure space for a sub is always critical, but becomes even more so when the box is ported. With sealed boxes there's usually a little "fudge room" in there. I.E. 2.1cf net won't alter your tuning significantly over 2.0cf net.
    Whereas with a ported box, it will.

    Tuning and power handling are also effected by box size.

    That said, I'd go with the smaller 10" driver and the lower tuning. A 10" driver will also have marginally less displacement than a 12" driver will, netting you a bit more airspace.

    These are rough figures, but:

    Starting space 2.5cf
    Minus driver displacement
    Minus port displacement
    Minus bracing displacement

    Leave you with about 2.0-2.2cf net.
     
  3. Marc*F

    Marc*F Stunt Coordinator

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    Thanks for the reply, 2.5 would be after displacement...and unfortunately that is the size limit, but would I be on the right track to assume a smaller sub eg. 10" would respond and hit lower in the larger box compared to the 12" same box same tune but less relative space?
     
  4. MichaelDDD

    MichaelDDD Supporting Actor

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    Hmm. A NET airspace of 2.5cf is not that bad. You might be able to get away with a 12" in there...but depending on which 12" you choose, the tuning might not be as low as you desire.

    In a ported box, tuning is a function of airspace + port diameter and length.

    I had a 3.0cf net ported box...it was big. [​IMG] So I know where you're coming from.

    If space is a primary consideration (and it sounds like it is) you do know that the box doesn't have to be a square (in fact, it shouldn't be a square).

    You can make it narrow, but tallish. Or short, but wide, etc.

    Are you trying to fit the sub's box in a specific space?
     
  5. Marc*F

    Marc*F Stunt Coordinator

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    It's not really going in a certain spot, but i would like to keep the footprint on the smaller side and like you said make it a bit taller...I'm thinking a 10" sub to hit lower as the box will be larger compared to the 12"....any recommendations on a 10" sub that will get low (I'm planning to tune around 22hz) with around 300wrms? Also the budget on the sub will be no more then around $180 or so...
     
  6. Mike Allen

    Mike Allen Stunt Coordinator

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    Have you checked out the Adire Shiva? It will do good in their spec'd box designs they have on their site. There is a design for a 85 liter(3 cubic feet) box tuned to 20Hz. I doubt you'd be disappointed with it(do a seach in the DIY section of this site). Get the PartsExpress 250w plate amp for about $130. For less than $250(not including wood, etc. for your box) you have a sub that is very hard to beat for the price.

    Adire Shiva
    There are 3 designs on THIS page. The one I'm talking about is the first one(Section 4.1).
    Enjoy.
    Mike Allen
     
  7. Marc*F

    Marc*F Stunt Coordinator

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    I have seen the Shiva and the smallest box recomendation, but I am wondering if a good 10" sub might perform better in that sized box........
     
  8. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    I'll second the reccomendation for the Shiva. And I'd also consider the 12 inch Dayton DVC from parts express. Or maybe the new budget driver (1204?) from Stryke.

    The only 10 inch driver I know of that would really be adequate is the Titanic Mk2 from parts express. You'd get a nice EBS alignment in 2.2cu ft tuned to 22Hz. Flatter than the 12's in 2.5cu ft.

    But the 12's will have about 2-3dB more output from 35Hz on up. These are very much like the "Adire alignments" in that they perform somewhat like a sealed sub (lower group delay, low-Q rolloff) but still retain decent low-end extention.

    And let's not forget that the 12 inch DVC and Shiva are actually CHEAPER than the 10 in Titanic Mk2. I'm not knocking the Titanic by any means, but this seems like a no brainer to me.
     
  9. Marc*F

    Marc*F Stunt Coordinator

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    The Shiva will probably be my choice if I can't find anything eles....I'm not that interested in getting it loud more to get low and rumble....any other 10" recommendations?
     
  10. Marc*F

    Marc*F Stunt Coordinator

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    I've noticed the Dayton Titanic mk ii 10" sub recomended....considering 2.5 cubic feet tuned low to 22hz would it hit lower then a shiva in that same box size?

    How are the quality of the PE 250watt plat amps on partsexpress.com aswell?
     
  11. Mike Allen

    Mike Allen Stunt Coordinator

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    Don't know about the Dayton, but the PE amps are used by many many people. It's one of the best amps for the money out there. I believe I remember hearing it benched @ 280watts. I haven't heard any complaints about them. Do a search in the DIY section and they're discussed more there.
    Mike Allen
     
  12. Joe Ku

    Joe Ku Stunt Coordinator

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    Look at the Stryke audio AV-12, in a 2.1 cuft internal box, port tuned to 23.5HZ has an Anechoic F3 of 24.5HZ, in room F3 will easily be below 20HZ in small rooms or corner loaded.

    The dayton 12" DVC in a ported 2.1cuft box will have an Anechoic F3 of 29.5hz.

    10" Titanic MK-II in an 1.4cuft ported box will have an Anechoic F3 of 28.3hz.

    I own both an AV-12 and a 12" Titanic MK-II and am very impressed with the quality of both drivers. I would suggest you look at the rythmik audio 350 watt plate amp if you choose the AV-12 ($150 shipped I believe) as it is a little less efficient that some, but that is the tradeoff for going low in a small box.

    The styrke audio site is under construction, you can look at the woofer but ordering is not online, so call the phone number and talk to them if you want to order one.

    Rythink audio has also just released an LT transform option for their amps (to be used with sealed subs only) but it may be worth looking at, you may want to call brian ding and ask him about it, could be a good solution if you don't need 110db but want accurate and low at moderate volume.

    www.stryke.com
    www.rythmikaudio.com
     
  13. Marc*F

    Marc*F Stunt Coordinator

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    How do the first two recommended boxes for a Shiva compare to each other? I would guess the third largest box goes quite low [​IMG] I can probably only do the smallest recommended Shiva box, but if the one up can get much lower or sound much better for HT i might try that....and how does a sealed Shiva compare? 3cubic feet will probably be my MAX....
     
  14. Robert_Gaither

    Robert_Gaither Screenwriter

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    If porting is your desired option I'd recommend that maybe you might want to go with passive radiators to keep the small box alignment.
     
  15. Marc*F

    Marc*F Stunt Coordinator

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    Considering I can have a box size of 95 litres which Adire enclosure will offer the lowest bass extention for HT applications? Sealed? Vented or a Passive Radiator?

    Are there any negative things when using a passive radiator to a normal vented enclosure?
     
  16. Robert_J

    Robert_J Lead Actor

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