El Cheapo Speaker Project

Discussion in 'Home Theater Projects' started by Chuck Bogie, Mar 31, 2003.

  1. Chuck Bogie

    Chuck Bogie Second Unit

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    Okay - Spent the weekend thinkin' on the "El Cheapo Speaker Project."

    Going to start with a pair of the Goldwood 12" 312/8s from the Parts Express sale flier ($14x2) clamshelled into a 1.6 cubic foot sealed box, which will give me 4 ohms, and according to the nice guy at the Parts Express tech support, an f3 of 33ish. It'll be driven by a 100 watt plate amp. The upper end will be essentially a BR-1 in a separate ported box, and will use the crossover on the plate amp to separate the low signal for the woofs...

    What do y'all think?

    As an aside, started in messing with the math - Sheesh - these things have a high Q... And an EDM (or whatever that was) of around 10ish...

    Am I screwing the pooch on this one?
     
  2. ThomasW

    ThomasW Cinematographer

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    There's a reason they cost $14ea. That driver has a 3mm Xmax. I wouldn't recommend using it for anything.
     
  3. Justin Ward

    Justin Ward Supporting Actor

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    Those drivers would bottom really easily. You would need about 6 of them to get decent total VD I think. I think you'd be better off with one decent 10 inch driver.
     
  4. Chuck Bogie

    Chuck Bogie Second Unit

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    Okay - that's out then...

    What sort of x-max should I look for? I'm not looking to shake walls here - just to fill in the low end... I've been listening to stuff, and I'm thinking that I definitely want to go sealed for the box.

    What about this one?

    12" Goldwood Butyl Surround

    Xmax is 5mm, but the thing also looks like it'll want a 4'+ box...
     
  5. Andrew Low

    Andrew Low Extra

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    For a cheap sub.. search around for a used SVS driver.
     
  6. Chuck Bogie

    Chuck Bogie Second Unit

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    How do the SVS drivers work in a sealed box? Has anyone done one? Do you know how large I'd have to make the box?
     
  7. Geoff L

    Geoff L Screenwriter

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    Chuck

    An original SVS 12" driver sealed in a 2ft^3 box & 75% or more stuffed works quite well for home use. Very tight sounding.

    Below is with out stuffing and you could figure a gain in VB of 25% + with 75% + stuffing. Dropping the Q even further.

    VB-2.0ft^3
    Q- .68
    FC-37hz
    F3-39hz

    With room gain, (corner load) getting into the upper 20's with good spl is not a problem. But if your using them in your mains and of course not being corner loaded, you loose some of that free gain.

    It models, with the limited TS-params Tom V posted some time ago, similar to the 12" Shiva. You loose some out put and extension compared to a ported/PR'ed design, but need not worry much about bottoming the driver, short of flat out overpowering it. The Rythmik-350 makes for a nice match, amp wise with selectable SS freqs and selectable freq boost, none, mild 1.5 and max 3db boost.

    Ported in about 3.5ft^3 for the SVS looks pretty good, max flat.

    Are these speaks going to be the LFE for your system or do you have a seperate subwoofer for that?

    Edit:
    For a Q of .707, a box volume of 1.8ft^3 is what I am getting..... This is the "smallest sealed" I'd go and stuff the shit out of it....100% stuffed about a pound and 3/4's to 2-lbs.

    Regards
    Geoff
     
  8. ColinM

    ColinM Cinematographer

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    I have an 88l SVS ported, tuned to 24hz. Great bass. Plugging the port is fun, but I prefer the balance afforded by the port's lower response. I actually prefer the port open for music.
     
  9. Geoff L

    Geoff L Screenwriter

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    Colin

    Have you run sines threw your SVS at 1-meter or very close to the sub to help elimenate room interaction?

    Did you by chance throw a few pounds of fill in it?
    99-L tuned to 22hz seems max flat.

    Do you have a spike around the 30hz area?

    Not room induced spike, but due to the alignment, size, and tuning you picked (88-L 24hz tune).
    I am very just curious.
    Sounds like it would be a real chest hitter.

    Geoff
     
  10. KyleGS

    KyleGS Second Unit

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    Search eBAY or Yahoo! shopping for the JBL GT120. It models much like the Shiva. It has about 24mm p-p and is a little less then $50 street on eBAY or Yahoo! shopping.
     
  11. Bhavesh P

    Bhavesh P Extra

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    I'm with Kyle, your best bet is to buy a subwoofer used, so that it will still be cheap. From car audio, MTX 4000, bazooka EL, jbl lc & (some) gt, and Kenwood tornado series subwoofers go pretty cheap. Just make sure you pick up a single voice coil 4ohm sub, and it should work in almost any sealed box 0.5-1.75 cubic feet big. I have a Kenwood Tornado sub I got for next to nothing after a friend of mine got out of car stereo, which I threw in a 0.5 cubic foot sealed box (homemade for $8) and with the 250W Partsexpress plate amp. The amp is too much for the sub, but even with the gain 1/4 way up, it's still the loudest stereo in my residence.
     
  12. ColinM

    ColinM Cinematographer

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    G -

    Lined, not filled. I EQ it at the listening position, killing a hump around 60Hz. It's flat to about 23hz, then drops off - amp has a 19hz rumble filter, and I'm happy with that, too. Never bottoms out.

    Loud? Yep. [​IMG]

    The alignment is based on Adire's plans, the smallest ported Shiva design. In WinISD, it looks great.

    88l is about where it came out, after fudging some of the cuts.

    I paid $45 for the driver, $99 for the amp shipped. I feel it is nearly (not quite) the same as my 20-39 used to be, without all the extension, but very close.

    Chuck - if you can find one of the JBL GT120's, its virtually the same spec as the SVS, and yahoo shopping has some for $49 each. That's the one I'd get if I couldn't find an old SVS driver.

    - CM
     
  13. Geoff L

    Geoff L Screenwriter

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    C- [​IMG]

    Cool, what a deal.
    Now thats DIY on the cheap with real performance that the commercial offerings (at your investment) could only dream of.....

    I also agree, go get the JBL if an original SVS is not to be had.

    Geoff
     

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