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Reload Thread: sub / custom box / SQ ??

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    res09ggm's Avatar
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    sub / custom box / SQ ??

    I've been reading up on fiberglassing techniques for a custom mold in your trunk for the sub.. My question is, is the fiberglass a good enclosure for a sub? Also, does how does the shape of the box affect sound quality and / or wattage? I've read somewhere that each sub carries its own specifications for box dimensions. How would you factor box dimensions into a custom fiberglass enclosure?

    Also, doesdoes a ported / sealed / bandpass enclosure differ in terms of sound output / quality and such? Just curious. I kno that theres no one superior box, so let's leave that out of the picture.. I'd just like to know how each box differs and offers and advantage.

    If i wanted to, could i create a fiberglass enclosure of any shape and stick a sub in it? Last question: 1" MDF is best for wood enclosures.... am i correct? so.. how thick would fiberglass have to be to achieve the same output / quality?







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    Fiberglass is pretty strong and people have used it to good effect. I think that in a sub application using fiberglass, just try to make it as thick as realistically possible. The shape of the box really doesn't matter, it's all about the volume of the enclosure. The volume of the enclosure will affect sound quality and power handling. Each subwoofer has its own characteristics that you can use to design an enclosure that will hopefully meet or exceed your tastes. To figure out the volume of a fiberglass enclosure, can't you fill it with water after it's cured?

    ported, sealed and bandpass enclosures differ very greatly with respect to sound quality and output levels. Ported = loud, and if you design it right, can go very low and have sound quality, but this depends on the subwoofer driver too. Bandpass = loud, but in a certain frequency range usually and doesn't have very flat response and tend to not have good sound quality unless you know what you're doing. I personally have no clue how to design a proper bandpass enclosure. And, sealed can arguably produce the flattest frequency response and best sound quality, but usually at a cost of loudness.

    Yes, you could build a fiberglass enclosure of any shape and stick a sub in it. And about the wood, I heard Marine Grade Plywood (9ply or greater) has very good strength and will outperform 1" MDF. Now, I can't exactly explain this, I just read some audio heavyweights, such as dan wiggins (of adire audio) say that he prefers both marine grade plywood and baltic birch over MDF because they are stronger. The disadvantage to Marine Grade Plywood or Baltic birch (9-13 plys) is that it is much more expensive than MDF. MDF does work great and 3/4" is good as long as you use sufficient bracing.

    And, I have no idea how thick the fiberglass would be in order to acheive the same performance as 1" MDF.



    DEX-P9 (headunit)
    DEQ-P9 (30band eq L/R, time alignment, 36dB/oct 4 way crossover)
    Soundstream Tarantula (for subs)
    Precision Power PCX-4125 (for horns and midbasses)
    Image Dynamics CD2 comp mini horns
    Scan-Speak 7" 18W/5535A midbasses
    Subs still pending.

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    ramos's Avatar
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    Thickness of the glass depends on the weight of the mat that you use. The heavier the mat the less layers will be needed.

    Let me offer a tip to cut down on the amount of materials you will need. After you lay your first couple of layers of mat. Lay in some resin soaked rope. The kind of rope really doesn't matter. The rope will make ribs. These ribs are going to strengthen the enclosure considerably. Then lay a couple more layers of mat over the rope. Also when your laying the mat. Be sure to use a roller to work all the air bubbles out. And be patient



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    res09ggm's Avatar
    res09ggm is offline Junior Member

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    you refer to flatness... does that mean how low and loud it can go ?




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    dreamer's Avatar
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    sorry about the lack of clarification.
    flatness is when the frequencies play at the same sound pressure level compared to other frequencies.
    a perfectly flat speaker will play all frequencies from 20Hz - 20,000Hz at the same volume.

    a sealed box without any transfer function will not typically play very low, but in a car, because usually the wavelength of the wave is longer than the car itself, the low frequencies get boosted a whole lot, and makes up for the lack of low end in sealed, and usually produces quite a flat response. Some people in sealed boxes have gotten it to play down to 10Hz pretty decently. But, if you tune the right speaker in a ported box to the right low frequency, the amount of low frequency it produces is astounding.



    DEX-P9 (headunit)
    DEQ-P9 (30band eq L/R, time alignment, 36dB/oct 4 way crossover)
    Soundstream Tarantula (for subs)
    Precision Power PCX-4125 (for horns and midbasses)
    Image Dynamics CD2 comp mini horns
    Scan-Speak 7" 18W/5535A midbasses
    Subs still pending.

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    soo...what i would like is a sub that hits hard and very low, and very loud when low... the kind where everything shakes, but feels great... so i would acheive this with a ported box, if its ported correctly.. or a sealed box? I bought a Visonik 10" bandpass V102BP for $99.99 a while back.. At the time i thought it was a steal, bandpass + 2 subs, 500watts rms... but now I don't know... Does anyone have any comments on the V102BP? It sure looks great though for a hundred bucks.




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    it depends on how much money you wanted to spend.

    the visonik bandpass box may provide some thump, but, I think it will be very pale compared to something that is well thought out and well designed.

    if money wasn't a factor, I'd suggest 2x 12" brahmas in a ported enclosure of 4 cubic feet total tuned to 24 Hz.

    some other drivers to look into
    blueprint
    idmax
    jl w7 (very expensive... very)
    re xxx

    I could suggest more, but the above should give some sound quality too.



    DEX-P9 (headunit)
    DEQ-P9 (30band eq L/R, time alignment, 36dB/oct 4 way crossover)
    Soundstream Tarantula (for subs)
    Precision Power PCX-4125 (for horns and midbasses)
    Image Dynamics CD2 comp mini horns
    Scan-Speak 7" 18W/5535A midbasses
    Subs still pending.

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