Building the Simplest, Best Sounding, Yet Most Inefficient Audio Amp!

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Introduction: Building the Simplest, Best Sounding, Yet Most Inefficient Audio Amp!

About: Awesome Electronics Tutorials, Projects and How To´s

In this project I will be showing you how to create a class A audio amp. The great thing about such amps is that they only require a few components and sound awesome. On the other hand though, their efficiency is not that great. But since I will be creating this amp for a smartphone with a USB Type-C port for powering the amp, it should be just fine. So let me show you how to calculate a design for such an amp and how to build it! Let's get started!

Step 1: Watch the Video!

The video gives you pretty much all the general information when it comes to building a class A audio amp. During the next steps though, I will present you some additional details.

Step 2: Order Your Components!

Here you can find a parts list with example seller (affiliate links):

2x BC337 NPN BJT: https://s.click.aliexpress.com/e/_9I1F1z

2x 100Ω, 2x 22Ω, 2x 3.3kΩ, 2x 1kΩ Resistor: https://s.click.aliexpress.com/e/_dTPpXjt

4x 10µF Capacitor: https://s.click.aliexpress.com/e/_d7dOwRz

1x USB Type-C breakout board: https://s.click.aliexpress.com/e/_AonKUJ

1x Audio jack: https://s.click.aliexpress.com/e/_9IfcXd

1x Audio plug: https://s.click.aliexpress.com/e/_ABC7UL

1x Perfboard: https://s.click.aliexpress.com/e/_A5V4B5

Step 3: Build the Circuit!

Here you can find the schematic of the circuit along with reference pictures of my own board. Use it to solder up your own amp.

Step 4: 3D Print the Enclosure!

Here you can find the .stl files for my enclosure. Print it with your 3D printer and put your class A amp inside!

Step 5: Success!

You did it! You just created your own class A audio amp!

Feel free to check out my YouTube channel for more awesome projects:

http://www.youtube.com/user/greatscottlab

You can also follow me on Facebook and Twitter for news about upcoming projects and behind the scenes information:

https://twitter.com/GreatScottLab
https://www.facebook.com/greatscottlab

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    21 Comments

    0
    KB3BYT
    KB3BYT

    Question 3 months ago on Step 3

    Is this the correct orientation to use electrolytics in this circuit for C1 and C2 ?

    amp.jpg
    1
    KB3BYT
    KB3BYT

    3 months ago

    WHAT ARE those yellow gumdrop shaped capacitors? Are they non-polar? Is there a PLUS and MINUS side ? Your ALIEXPRESS web link takes me to ELECTROLYTIC capacitor assortments. Can you revise the schematic to show PLUS and MINUS using electrolytic capacitors? I have 10uF electrolytics here now.

    0
    aaamott
    aaamott

    Reply 3 months ago

    Those are ceramic capacitors, non-polar. The positive side goes on the side attached to VCC and negative (side with a white band) goes to the side labelled "out"

    0
    JohnC430
    JohnC430

    Reply 3 months ago

    those are Tantalum caps. they are polarized just like the Aluminum electrolytic caps and are better quality, less leakage and do not deterioriate over time like the other.

    0
    KB3BYT
    KB3BYT

    Reply 3 months ago

    can you mark the circuit to show which way is plus and minus for each capacitor?

    0
    nkoliha
    nkoliha

    Reply 3 months ago

    Tantalum capacitors

    0
    lifexeMPLAR
    lifexeMPLAR

    Question 3 months ago

    and are the capacitors polarized? how do I solder them in if so (the ones you linked on aliexpress are electrolytic)

    0
    aaamott
    aaamott

    Answer 3 months ago

    Ceramic capacitors are not polarized. If you switched to electrolytic (which look like little cans) you would look for the side marked with a row of negative marks, usually along a white band.

    0
    changkho.acam95
    changkho.acam95

    Question 3 months ago on Step 3

    how is it usable on google pixels? Thank you Sir

    0
    changkho.acam95
    changkho.acam95

    3 months ago

    how is it usable on google pixels? Thank everyone

    0
    JohnnyMehl
    JohnnyMehl

    Question 3 months ago

    The schematic shows a stereo a amplifier but output jack is a single switched output?

    0
    danielabrams555
    danielabrams555

    Answer 3 months ago

    The schematic shows a mono amplifier. The component list has enough components listed to built two of these circuits, which you will need to do if you want stereo sound. Notice the schematic shows only two capacitors, but the picture of the circuit on the perf board shows four capacitors. To get stereo sound you build a separate amplifiers for right and left signals.

    0
    lifexeMPLAR
    lifexeMPLAR

    Question 3 months ago

    Hi, is the ground of minijack connected to the ground of 5v line? thanks

    0
    yakacm
    yakacm

    3 months ago on Introduction

    I can't help but read the intro in my head in Great Scott's voice, and that being said...

    0
    ndbaker
    ndbaker

    4 months ago on Step 5

    Anyone try it with a rechargeable battery so it doesn't drain the phone?

    0
    nkoliha
    nkoliha

    Reply 3 months ago

    Should still work you just need a good enough lipo a booster and a good charge on protection

    0
    peximus
    peximus

    Reply 3 months ago

    I suppose if you open the circuit in VCC and you put an Amperemeter, you can check how much current it will use (theorically, it uses 20mA aprox., but if you want to know the real current, do what I said)

    0
    doctor_g
    doctor_g

    3 months ago

    No matter how good your amp is, it's amplifying the output of the phone's Digital-to-Audio Converter, which is the weak link in the audio chain.

    0
    ANISHP23
    ANISHP23

    3 months ago

    What will be the value of all resistance if I used a 9v battery and instead used electret micas input?(I want to make cheap mic amplifier).

    0
    gbrajovic
    gbrajovic

    Reply 3 months ago

    I don't think it woukd be useful as a mic preamp, it is imposible to get the necessary gain from a single transistor.