guitar Amplifier

Discussion in 'The Projects Forum' started by bluegreen, Jan 19, 2012.

  1. bluegreen

    bluegreen Thread Starter Member

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    Hi,

    I am planning to design a low end solid state guitar amplifier with distortion from scratch. Could someone guide me and help me with suggestions as to how to go about doing this and what books and references I need to use to complete this.
  2. bountyhunter

    bountyhunter Well-Known Member

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    You can add the distortion circuits, there are a number of them around. I built one back in the 60's called a "fuzz box" which was a two transistor distortion booster.

    As far as the amplifier, there are tons of circuits around but I don't know what input level/impedance and output power you need.
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  3. PaulEE

    PaulEE Member

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    I'm in the process of doing this exact same thing, only I have a tube pre-amp.

    The distortion isn't a big deal...were you thinking solid state with discrete components, or solid state with a chip amp?
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  4. MrChips

    MrChips Moderator Staff Member

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    You need to say how many watts of power you need? What diameter, power and how many ohms is the speaker? How many inputs? Bass/mid/treble controls? Foot switch for distortion? How about foot switch for power boost? What type of music you play? Acoustic guitar with pickup or solid body electric? Classical, folk, R&B, jazz, rock, heavy metal?
  5. bluegreen

    bluegreen Thread Starter Member

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    Thanks for the input guys. I have not yet decided on the specifics. I would prefer simple discrete components and basic ICs over chips which have an all in one functionality. Maybe a tube preamp and o/p power of 3-5W.
  6. bluegreen

    bluegreen Thread Starter Member

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    acoustic with pickup and an electric Ibanez
  7. PaulEE

    PaulEE Member

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    A great reference is a book called "microelectronic circuits" by sedra and smith.

    In this book and in many other places, you might run into an op-amp + push-pull transistor amplifier circuit. These are great little circuits to start with, especially in the few watt range. Though it is a bit much, the OPA2227 is a great op-amp for a few reasons; low noise, high open loop gain, low distortion, and moderate output current.

    The output current capability allows the op-amp to be connected straight to the push-pull stage. In unity-gain configuration, with the "-" lead of the op-amp connected to the output of the push-pull, the op-amp biases the transistors as necessary and provides an overall low-distortion circuit.

    I just got done playing with my circuit: the OPA2227 has two separate amplifiers; one I used as non-inverting voltage gain (gain of about 100) and the output was fed into a unity-gain follower like the circuit I described above. The unity-gain follower uses some hefty MJL/MJE transistors (that will eventually be cranking much more than my little ten watts). It wasn't shaking the house apart, but it was plenty loud in my bedroom with my telecaster hooked up to it... :)
  8. MrChips

    MrChips Moderator Staff Member

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    I don't think 3-5W would be of much use. I would up it to 10-15W.
  9. PaulEE

    PaulEE Member

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    I think 3-5 watts is fine for someone who is looking to get acquainted, don't you?
  10. THE_RB

    THE_RB AAC Fanatic!

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    Yep. Many small practice amps used a 1W LM386, which is loud enough to be annoying in a bedroom, and louder than a person singing and louder than an acoustic guitar.

    But if you play alongside a real drummer you need 50W+ (and you need somewhere to practice!!). ;)
  11. PaulEE

    PaulEE Member

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    True that!
  12. sg19803

    sg19803 New Member

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  13. PaulEE

    PaulEE Member

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