Homemade amp

I'm completely new to this electricity stuff. Last night I hacked a pair of old computer speakers into an amp. Just clipped the input wires where they came in the back of the powered speaker and soldered them to a jack. Works fine, but very little volume. Is there any additional hack which would improve that any? Simple piezo pickup in an acoustic instrument.

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  • Piezo/Mag pickups don't kick out as much juice as the line-out from the computer, so yes the volume is less, but pat youself on the back, it worked!

    • It did, but worked even better, except for portability, patching into an old stereo receiver with a air of old JBL speakers.
      • Unless you were using a mic level input on the old receiver, its likely you could still get even more volume with a preamp bringing the signal to line level.

        I have a 2x100 Watt stereo board wired up that expects line level - play a song from my phone I can't turn the volume all the way up without worrying about my hearing.. Plug in my lil guitar and try to turn it to '11' and you can almost hear crickets amplified with the weaker signal.. 

  • I have used dozens of these to make amps,  add a 9v battery clip and a 4”speaker...   I buy used speakers at goodwill for cheap.  Most work fine.

    https://www.ebay.com/itm/Low-Voltage-Audio-Amplifier-Module-Kit-NJM...

    if you solder a 1k resistor to the gain jumper position, you have an adjustable gain.   They get a little crunchy, too...

    the other other option is to put a preamp in front of it, ( Gitty sells  an awesome one)... or the Psycho knob distortion module...  gives you a cheap practice amp.    

    You could run it on 6 AA’s... 9v last a few hours, 6 AA would last much much longer.

    • Much to think about there. I'll go look, thanks.

  • This is gonna sound almost too dumb to work but...

    Dollar Store powered speaker... like something that runs on a few AA batteries and is meant to take input from your phone... 

    Grab out the main board from that, put instrument into the input and connect the output to the in on the speakers... 

    its what I did for my lil cigarette pack guitar... I actually use one of them rechargeable bluetooth speakers as the 'amp' part though and just connected everything with 3.5mm stereo jacks ( my guitar's piezo is wired to left side, my preamp can switch between left and right for output but expects input only on left )

    check my videos / pics. 

    other suggestion would be a simple smokey amp style circuit.. 

    • That's pretty advanced for me, but it kind of hints at stuff I've been wondering about. I'll go look at your stuff.

  • RTZGUITARS is right all you need is a simple 1 knob boost pedal.there are many kits around on the web or premade. tone city etc... no need for expensive ones.  advantage is that a boost can always come in handy. gives a kick in volume. or if fed into a drive pedal can push it harder... 

    JL has a point too, for something simple and already premade. just get a gitty preamp and pop it in a small box. plug into it and it into the amp.. easy. 

  • use the cb gitty pre-amp, its easy to cut its piezo and solder a jack in its place

    • If you want to build a amp its easy, but you can get a amp kit from gitty they work great

      here's the smoky amp diagram based on Texas instruments lm386

      Image result for smokey amp diagram

      blue is the caps you don't need the one on 7 but you do need a poly cap on the speaker cap to ground

      if you put a pot between 2  you get volume control

      a pot between 1 and 8 gain control. And can also you a resistor to set the gain between 1 and 8

      there are tons of variations google lm386 diagrams

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