Bumble Tuby Guitar Amplifier

This is a simple, hybrid guitar amplifier, made as a hobby project. More applicable for learning and practice, rather than anything else. Outputs around 1W of power.

Features

• Runs off of a single 12V DC supply.
• Pre-amp based on the 12AX7 vacuum tube.
• Power amplifier based on the LM386 IC.

Bill of materials

Note

This section is yet to be populated.

To-do

Circuit design

• Add headphone output.
• Add effects loop:
  • FX send can be driven directly from the 2nd tube stage.
  • FX return needs a buffer before feeding into the power amp section. Can use the second half of the NE5532 for this.
  • What about operation modes? With/without effects loop. This would require a SPDT switch to either send the pre-amped signal into the effects chain, or directly into the buffer.
• Add bypass capacitors on power supply lines:
  • LM386: 10uF, 100nF
  • NE5532: 10uF, 100nF
• Add power switch, LED
• [ ] Bridge the two LM386s for twice the power
  • https://runoffgroove.com/littlegem.html
• Consider poweramp alternatives
  • TDA2030
    • Obsolete but cheap and widely available
    • Widely used in many commercial guitar amps (or TDA2050)
• Design perfboard layout
• Add a tone control section.
  • Between tube stages?
• (?) Add gain adjustment for the power section (LM386 pins 1-8)

CI

• Render BOM into README, as a Markdown table.

Credits

This design was inspired by:

• Ruby Tuby amplifier design.
• Tube Cricket