How To Make A Guitar Work Through a Homemade Boombox?

Discussion in 'Analog & Mixed-Signal Design' started by coolyyz321, Jun 11, 2018.

  1. coolyyz321

    Thread Starter Member

    Mar 17, 2017
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    Hello, I am making a homemade boombox and want to wire a 1/4” Aux Jack to plug a guitar into. What parts would I need after that to make it work? (The system will feed into the main amplifier)

    Is it as simple as wiring a small preamplifier from the 1/4” jack and then into the main amplifier?

    Thanks, Cody
     
  2. ian field

    AAC Fanatic!

    Oct 27, 2012
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    Clarify what you mean by "homemade boombox"? A commercial unit probably has 5k volume pots that will just shunt the high impedance pickups. I'd suggest a JFET source follower using the pots as the load resistor. It will pass current through the track and develop voltage across it - you probably need to lift the track from the source select switch.
     
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  3. coolyyz321

    Thread Starter Member

    Mar 17, 2017
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    This diagram shows where the guitar system would be placed in the boombox. What I mean by a homemade boombox is as shown in the diagram, the audio comes from a car radio which has Bluetooth, CD, Line in, etc. From the car radio is a mono audio signal that feeds into the main amplifier. Which in turn plays through the speakers.

    The explanation for the guitar system is the audio coming from the guitar going into the 1/4” Aux. jack that goes into the “circuit in question”. The goal of the circuit in question is to beef up the signal to be fed into the main audio line to be amplified.

    Thanks, Cody



    B516617F-9E60-4662-9BFB-09D6933EA4D2.jpeg



     
  4. ian field

    AAC Fanatic!

    Oct 27, 2012
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    JFET source follower.
     
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  5. coolyyz321

    Thread Starter Member

    Mar 17, 2017
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    Would this circuit be a good JFet source follower circuit?
    9B05E32B-918E-4106-BCA7-661820FC6699.jpeg
     
  6. dendad

    Well-Known Member

    Feb 20, 2016
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    And some form of audio mixer would be a good idea, not just hooking 2 audio sources in parallel.
     
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  7. coolyyz321

    Thread Starter Member

    Mar 17, 2017
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    Thank you for your help, I found a small mixer that will work, I will add it to the list.

     
  8. ian field

    AAC Fanatic!

    Oct 27, 2012
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    Probably easier to decide which signal source you don't need and hijack that tag on the selector switch.
     
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  9. coolyyz321

    Thread Starter Member

    Mar 17, 2017
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    Hello Ian, are you meaning wiring a button or switch of some sort to switch sources from one to another?

     
  10. BobTPH

    Senior Member

    Jun 5, 2013
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    That would be best, unless you want both sources playing at the same time.

    Bob
     
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  11. coolyyz321

    Thread Starter Member

    Mar 17, 2017
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    Thank y’all for all of you guy’s help, but what transistor, capacitor and resistor values would be good for the JFet source follower circuit?
     
  12. ian field

    AAC Fanatic!

    Oct 27, 2012
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    I suggested deciding which signal source was no longer needed and isolate it from the existing switch - that tag can then be the guitar input.
     
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  13. Audioguru

    Expert

    Dec 20, 2007
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    Here is a recommended preamp for an electric geeetar:
     
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