Fork me on GitHub

Project Notes

#249 AudioAmps/GuitarPracticeAmp

Single-channel 10W guitar practice amplifier based on the TDA2050

The Build

Here’s a quick demo, clean tone from a Spanish guitar with built-in pickup:

demo - clean

Notes

This is a 10W guitar practice amplifier circuit and was designed for the Fundamentals of Audio and Music Engineering: Part 1 Musical Sound & Electronics course offered by University of Rochester on Coursera.

The amplifier itself is designed to teach simple tone and distortion circuitry.

Parts

ID Qty Value  
R1 R3 R4 3 1 MΩ  
R2 1 5.6 kΩ  
R5 1 1 kΩ  
R7 R14 R16 1 22 kΩ  
R6 1 4.7 kΩ  
R15 1 2.2 kΩ  
R9 1 100 kΩ  
R8 1 10 kΩ  
R13 1 1 Ω  
R10 1 B50KΩ pot  
R11 1 B10KΩ pot  
R12 1 A10KΩ pot  
C2 1 47nF 473  
C10 1 100nF 104  
C3 1 10nF 103  
C7 1 220nF 224  
C9 1 100µF electrolytic  
C8 1 1000µF electrolytic  
C1 C4 C5 C11 4 1µF electrolytic  
C6 1 10µF electrolytic  
U1 1 TL072 DIP8 
U2 1 TDA2030 
D1 D2 2 1N4001  
LED1 1 3mm Red LED  
SPKR1 1 4Ω 10W  
S1 1 SPDT switch  
J1 1 12V power connector  
J2 1 6.35mm mono socket  

Hardware and other parts:

  • DIP8 IC socket (for the TL072)
  • SPDT power switch
  • 2.1mm power jack
  • 12V DC power supply
  • 1⁄4” Phono plug
  • speaker
  • perfboard/PCB

Cabinet Design - TODO

Some reasonable dimensions:

  1. A well rounded frequency response translates to a cabinet volume of roughly 5832 cm^3, or interior dimensions of 18 cm x 18 cm x 18 cm.
  2. For a bass heavy amplifier, a cabinet volume of roughly 2754 cm^3 will work better. This corresponds to interior dimensions of 18cm x 18cm x 8.5cm.

Styrofoam board can be used for a quick build, but a wooden case will sound slightly better.

I’ve mounted mine in a wooden box of about 2700 cm^3 volume, with a removable rear panel so I can experiment with tone.

Performance

Sample oscilloscope trace:

  • 12V power
  • CH1: input (1kHz, 20mV sine)
  • CH2: output, minimum gain & tone

scope_1khz_20mv

Construction

Breadboard

Schematic

GuitarPracticeAmp_protoboard_layout

GuitarPracticeAmp_protoboard_build

Credits and References

About LEAP#249 OpAmpAudio
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.