1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

will this work?

Discussion in 'Subwoofers' started by croozer, Apr 9, 2005.

  1. croozer

    croozer
    Standard Member

    Joined:
    Feb 15, 2005
    Messages:
    115
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Ratings:
    +0
    i am thinking of making a sub because the price of a new one is very expensive.perhaps using 2"chipboard,an 8" or 12"chassis speaker,a 110 watt car amplifier and a 12v power supply,all for a rock bottom price.does anyone think this idea will give out reasonable bass?would i need a filter on it as well?
     
  2. eviljohn2

    eviljohn2
    Well-known Member

    Joined:
    Jul 8, 2002
    Messages:
    7,529
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Location:
    Near London.
    Ratings:
    +208
    Loads of people on the forum have DIY subs, just do a search in this and the DIY sections. :)
     
  3. Nimby

    Nimby
    Member

    Joined:
    Jan 27, 2004
    Messages:
    9,201
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    The Danish Bacon Factory
    Ratings:
    +669
    Do you want the bad news or the very bad news?

    There are a lot of obvious problems trying to put a simple cheap subwoofer together.

    The natural resonant frequency (Fs) of the driver is likely to be very high with ordinary drive units with corrugated surrounds rather than rubber roll surrounds. Subwoofers usually use very low natural frequency drivers.

    The allowable cone movement (XMax) will be probably very small so it won't go loud without breaking something permanently. Subwoofer drivers are usually long-throw. Low frequencies need to move a lot of air to become audible. This means moving a cone a long way to pump the air required to reproduce low frequencies loud enough to be heard above the higher frequencies.

    2" chipboard is a bit thick! Even in 3/4" you'll be struggling to lift it if you make the box a decent size.

    Yes, you'd need a filter to stop the higher frequencies ruining the sound of your main speakers. It will be just like having three speakers in the room all competing with each other. But the subwoofer will be muffled and distorted.

    Car amplifiers run from a battery that is constantly re-charged. How will you provide a clean high-current 12Volts DC for any length of time? Any normal secondhand stereo amp would probably work better. While a proper subwoofer plate amp would do a better job and provide filtering too.

    You can't just throw a box together and hope it will be a subwoofer. All it will be is a woofer like any other loudspeaker. Not a real subwoofer. Unless you tune it very low with a long reflex port. But even then it will be difficult to get any output below (perhaps) 50Hz with a normal cheap driver.

    There are subwoofer designs called series bandpass subwoofers. These use more normal drive units but hide the speaker inside the box with only tuned ports (pipes) to let the bass out. They are also the most difficult subs to design and optimise in practice. Particularly as the drive unit has to be exactly matched (with expensive design software) to the box, its internal dimensions and port lengths.

    If you are so short of cash that a new subwoofer is impossible to afford (and we've all been there) I'd be saving and watching the secondhand market for the recommended subs you read about on the forum.

    Always keep in mind that a poor subwoofer is infinitely worse than no subwoofer at all. The money is always better spent on better main speakers.

    If you are determined to try and make a subwoofer then click on the BK Electronics advert at the top of the page for a line of good quality subwoofer plate amps.

    Nimby
     

Share This Page

Loading...