Help, building a passive sub...

Discussion in 'Archived Threads 2001-2004' started by DaveVan, Jan 24, 2003.

  1. DaveVan

    DaveVan Extra

    Jan 22, 2003
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    Im new here to the forums and to HT in general, so please forgive any obvious questions [​IMG]

    I just got a second hand entry level receiver (RCA RT2500) and now need a sub. This receiver has both a line-level RCA sub output and a built-in dedicated subwoofer amp with spring clip connectors. So I then have a choice of either a passive or active sub.

    Im guessing that building a passive sub will be both easier and more cost-efficient, basically get a driver and build a box around it [​IMG] Although I do not know how the crossover works with the internal amp, there is no adjustment I can see. The manual is not very detailed: Heres the .pdf manual
    The amp fed 200W into to the original 3ohm sub - a small ported enclosure (about 1 cubic foot) with twin 5" drivers.
    I tried the factory sub briefly, but the small dual drivers were obviously not getting as low as I would like, and there was considerable distortion above 1/3 volume. Im guessing the surrounds were well broken in - or just plain broken [​IMG]

    My front speakers (CerwinVega 200SE) already have 8" woofers, so Im thinking I will need at least a 12" sub. I will probably go for a ported design.

    I have never built a speaker before so I need some help with most of the details like:

    choosing size of enclosure/air volume/shape
    port length
    building materials
    method of joining panels
    driver model
    will this actually work when Im done?

    I have looked around at the faqs here but havent yet found anything on building passive subs, any links would be appreciated.

    EDIT: Sorry, just found the DIY forum, mods feel free to move this.
  2. Troy_j

    Troy_j Agent

    Dec 1, 2002
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    I would recomend that you goto the " DIY/Advance" forum and post this message there.....that forum is a huge resource for what you are asking. I would recomend that you do HTF search on your subject befor posting too. Good luck, I know you will get good education, and advice.
  3. Brian Fellmeth

    Brian Fellmeth Supporting Actor

    Jul 30, 2000
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    All the information here applies equally well to a passive sub design. There is really no difference- its just a matter of the physical location of the amp that powers the sub driver. Instead of a plate amp in the sub box, or a dedicated sub amp separate from the box- you simply will use an amp that is built into your receiver. I doupt very much that it can really put out an honest 200 watts though ....
  4. Frank Carter

    Frank Carter Screenwriter

    Mar 12, 2002
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  5. jeremiel

    jeremiel Auditioning

    Jan 12, 2003
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    Ok well first off.. a 12 inch is a good choice.
    Seconde ported is also good to get that deep low base... dino style.

    I make sub's for cars... so it seem the same.

    First off. What is you floor made of.. if you have a capet floor, I suggest a frontal sub. If you have wood, tiles, or anything hard then a floor sub...

    TO make a good sub... MFD is a good artificial wood.
    Very hard to work if you don't have good tools.

    3/4 to 1 inch for the size of the panel.

    To figure out the size of the box and port... use a box building program. You can find many for free. blauwpunk has one on the web site for free.

    what makes a box a good box are braces... and the sound proofing... you can buy some green panels called sonopath.. it works wonders.

    If you need any more help email me [email protected]

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