building subwoofer amp...

Discussion in 'Amps and Cabs [BG]' started by swassguy, Aug 15, 2003.

  1. I'm building a separate amplifier and cabinet for my lower frequencies, and I need some help.

    Here are the things I'm thinking I need right now:

    A speaker box
    A subwoofer (12 or 15 inch)
    A power amp (thinking 500 - 800 watts)
    A subharmonic synth (Furman Punch 10 or dbx 120)
    An A-B switcher to turn the signal on and off

    Has anyone else built one of these things? Is this all I'll need? Do I need more things, like a preamp or additional crossover? How big will my cabinet need to be?

    See, I've got all of these ideas, but usually I just know enough about what I'm doing to get the basic ideas down.

    Any help would be appreciated!
  2. thumbtrap


    Jun 26, 2003
    While it's quite possible to build your own power amp - in the really high power ratings, it may not be practical. Effects are low power, devices with lots of coolness for the amount of headache involved. Amps are slightly lower down the curve. Solid state power amps, are near the bottom of that curve - unless you want to build a switching power supply for it in which case we have to go to a new scale.

    There are guys, mostly audiophiles, who build their own massive solid state power amps. I'm looking at doing an 50w amp built on an LM3876 to run my shakers, but it's a low parts count thing without a lot of rocket science involved. I know they're out there because I ran into them researching my subwoofer amp project - but I'm not at my own computer now and don't have them handy.

    About half of your work is going to be in getting heat transfer. Routing while important - is not of critical importance to the degree it is in high gain and high frequency amps. If you want to save a buck, I submit that you're probably not going to, and almost certainly not prepared for the project. (If you were prepared, you would know about how much it would cost, what the commercial alternatives were, why they didn't fit what you wanted, and you would be asking on instead of These people don't know which end of the soldering iron to pick up and are afraid of things like table saws and routers. They're doing good to plug their bass into the correct amp.
  3. I'm not really thinking about actually BUILDING an amplifier - I was talking more about building an amplifier/cabinet setup that could handle subharmonic frequencies.

    No, no, I would find a power amp to run it.

    Thanks for the info, though.

    Yeah, if I wanted technical help on building a power amp I don't think I would look on a musician website :)
  4. I use a pair of Rockford 1x15 subs, each in 5.4 net cubic feet internal volume tuned at 20 Hz. These will handle my DBX 120 sub-synth, which reaches down to 26 Hz. I drive both with the left channel of my PLX 3002 which produces 900 watts into the total 4 ohm load. I use a Rane MX22 crossover in the rack along with the QSC, PLX, and SWR preamp. The highs are a pair of 1x10 JBL, or 4 total cabinets. Interconnects are with 12 gauge Speakon cables.

    The rack weighs 79 pounds, the subs about 150 pounds each. These pieces mostly fill the bed of my Toyota pickup truck when lying down flat (I have a low shell).

    The DBX 120 is a nice synth, but does not have a foot pedal control to activate it. A big disadvantage. It tracks exceptionally well, including chords, but only operates over a single octave range (55 ~ 110 Hz). It cuts off immediately outside this range. The octaver effect when it is operating is amazing if you have subs capable of producing 26 Hz. The DBX will turn non-subwoofer cabs into shrapnel at performance volume levels.
  5. Wow, that's a lot of equipment!

    What I'm trying to do is have my regular amp and then the subwoofer amp setup to handle really low frequencies. Something that I can switch on and off.