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Guitar Amp Modification

Discussion in 'General Electronics Discussion' started by hardyman16jm, Apr 17, 2013.

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  1. hardyman16jm


    Apr 17, 2013
    So, my band director gave me a broken amp, so I plan to fix it. If, and hopefully I will, I do fix it, my goal is take it a step further and mod the amp. I have a basic understanding of electronics, so don't go to hard on me. What I want to do is to take the input from the guitar, pass it through a tuner-like device where it can find out what note is playing, and then, depending on the note, make a different color LED light 'light' up. I'm not too sure on how to proceed with any of this, so I'd love any help with literally any aspect of this project from tuner to turning on the light bulb. Thanks!!
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    OK, you have 2 things here. First is the repair, second is the "colour organ" (google that).

    How about we work on the repair first?

    What is the make and model of the amp?

    What are the symptoms?

    Do you know how they developed?

    Can you locate a service manual for the amp?
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    So this "tuner" thing isn't a tuner, it just needs to detect which note is being played and light the appropriate LED?
    There are twelve semitones (aka "half-steps") in an octave, so I assume you'll want twelve LEDs, is that right?
    Or do you want a separate set of twelve LEDs for each octave? If so, how many octaves do you want to support?
    This kind of frequency determination would normally be done by a microcontroller. Digital filtering would be used to identify the fundamental frequency among all of the components of the signal, then the frequency would be fitted into a "bin" that covers the range of frequencies for that note, assuming the guitar is correctly tuned. Accuracy to about 1% or better would be wanted; a semitone represents a frequency change of 6%. As you can probably guess, this is not trivial!
    There are designs around that will try to identify frequencies and produce some kind of visual feedback but I don't think they'll be accurate enough. It depends on exactly what you want.
    Another possibility would be a PLL (phase-locked loop) driving an LED dot-graph IC. I tried Googling for a design but couldn't find anything. It would definitely not be a beginner's project anyway.
    You may be able to buy a ready-made product with frequency detection built-in, and adapt it to your application. For example, a chromatic tuner that has twelve indicators, or a frequency-to-MIDI converter.
    By all means, try a simple design. You will soon find out its limitations and you'll be able to tell whether it's worth pursuing.
  4. HellasTechn


    Apr 14, 2013
    As KrisblueNZ sayd

    There are devices that are called Cromatic tuners that do exactly what our friend here wants.

    Only havent seen one integrated into an amplifier.
    Last edited: Apr 18, 2013

    CDRIVE Hauling 10' pipe on a Trek Shift3

    May 8, 2012
    It wouldn't be the first device who's name is a misnomer.

  6. BobK


    Jan 5, 2010
    Tuner, here, means that is used to tune musical instruments. So not a misnomer.

  7. HellasTechn


    Apr 14, 2013
    The device i was reffering is called Cromatic tuner because it is used to tune musical instruments like guitars.
    i have no idea what a misnomer is !
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    A chromatic tuner is a device that listens to the pitch of the sound from an instrument, detects which note name the pitch is closest to, and allows you to tune the instrument to exactly the right pitch for that note.

    The scale used in Western music contains twelve different note names; the interval between any two adjacent notes is one semitone, aka half-step, a frequency ratio equal to the twelfth root of 2.

    The twelve note names are A, Bb (B flat), B, C, C# (C sharp), D, Eb, E, F, F#, G, Ab. After the end of this sequence, the note names repeat in the next higher octave, and so on.
  9. hardyman16jm


    Apr 17, 2013
    I actually know how to fix the amp, it's a pretty simple fix and I have done more than enough research on the topic. So how would I build that device though? While talking with some of my friends about this, we came up with the idea of a making a phone app, and my friends and I are excellent programmers, and use the microphone on the phone (We'd use an android or iPhone). Is there an easier way? Is it possible to just rig an actual guitar tuner and send the note information to the light system?
    Thanks for the help
    *PS I probably shouldn't have said tuner, I just meant something that can detect a note.*
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