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Has anyone built a power amp from scratch?

Discussion in 'Amps and Cabs [BG]' started by fender4, Mar 23, 2002.

  1. fender4


    Mar 22, 2002
    I am new to the board and was wondering if anyone has built an amp from parts (power supply, transistors, IC's, resistors, capacitors, etc.). I have built some simple amps for hi-fi home audio, and they sound great. I am thinking about adapting the circuit for use with bass.

    If you have, could you give a general description of it? Mine are based on the LM3875 monolithic IC from National Semiconductor. Thanks!

  2. You should send a PM to Joris.He is like tech guru
    deluxe!I think the guy makes most(if not all) of his own gear.He`s really handy at that sort of thing.
  3. Yup, I have built power amps.

    - My first project was a 40 watts one based on a TDA2030. Took weeks. Didn't work.
    - Then I bought a Velleman K4010 kit. Mosfet, 155 class A watts. Took a week or so to build. Still use it for practise (you can see a picture of it on my website under "small rig")
    - Did a stereo guitar amp of 2x70 watts with 2 TDA7294s. Really neat chips. Sold the amp built into a 4x10 cabinet. The power amp section took (I think) a week.
    - Then I bought a second hand Yamaha P1600. I like it so much that I will NEVER EVER build a power amp again.

    So in other words: buy a second hand power amp. It'll cost you about the same as home-built, and you'll be up and running within the minute, never worrying if it'll keep going.
  4. fender4


    Mar 22, 2002
    Thanks for the input, Joris! Great website. I agree that second hand is the way to go for power amps--I use a Sunn SPL7350 (700w @ 8ohms) that I picked up a few years ago for cheap. I am really happy with the results of my hifi amps, so I was just thinking about trying to adapt this same circuit to bass. I might bridge two of them (that should put me a little over 100w @ 8ohms) just for kicks.

    I like the T-lines you made for your hifi. I am thinking about building some Voigt pipes for a single driver, full-range project. Question: Is anyone using a T-line for a bass cab? Just curious. The size would probably be prohibitive.

  5. Hey F4,

    I think a transmission line is of no use to a bass player as they are sensitive to placement. They interact with the room too much. And you're right, the size of a high-power TL would probably get out of hand. I remember a Visaton design for a TL subwoofer, with a 15" and a 12" in a double TL config. The cabinet was I think 2.15 meters high and the base was like 45x45 cm.

    AMJBASS Supporting Member

    Jan 8, 2002
    Ontario, Canada
    Euphonic Audio uses a Transmission line design in all of their bass cabinets. My favorite is the 10" cab, which can handle 350 watts at 8 ohms. It is a tiny cab, which uses a coaxial speaker. The cab is rated down to around 40hz I think, complements of the transmition line design.
  7. : rant on :

    Somehow, I think I won't like the EA cabinets. It's just too good to be true. I take those specs with 12 onces of salt.

    The homebrew cabinets I use, would go down to 15 Hz if I'd measure them the same way. I spec them at 30 Hz, the point at which the free-space frequency graph starts to drop. In real life, they produce significant output below 20 Hz.

    I'm not trying to brag (or am I?) but that's what I call low end.

    : rant off :


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