Building the simplest, best sounding, yet most inefficient Audio Amp! || Class A Audio Amp Tutorial



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Transistor (BJT) as a Switch video: https://youtu.be/WRm2oUw4owE
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More project information (schematic,…..) on Instructables: https://www.instructables.com/Building-the-Simplest-Best-Sounding-Yet-Most-Ineff/

Parts list (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

Useful sites which were partly shown in the video:
https://www.electronics-lab.com/article/class-a-amplifiers/
https://learnabout-electronics.org/Amplifiers/amplifiers21.php
https://learnabout-electronics.org/Amplifiers/amplifiers20.php
https://www.tutorialspoint.com/amplifiers/class_a_power_amplifiers.htm
https://www.electronics-tutorials.ws/amplifier/amplifier-classes.html
https://www.electronics-tutorials.ws/amplifier/amp_5.html

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!

Thanks to JLCPCB for sponsoring this video.
Visit https://jlcpcb.com to get professional PCBs for low prices.

Music:
2011 Lookalike by Bartlebeats

0:00 Why I want to build a class A audio amp
1:02 Intro
1:39 General circuit design
3:03 Closer look at the Base Input side
4:24 Comparison of class A, B & AB amplifiers
5:30 Closer look at the Collector Output side
6:23 Selecting the complementary components
8:34 Extra Information about class A amps
9:05 Modifying a USB Type-C board to get 5V
9:53 Practical build & End

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29 thoughts on “Building the simplest, best sounding, yet most inefficient Audio Amp! || Class A Audio Amp Tutorial

  • March 10, 2021 at 9:16 pm
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    I have to build it for my Car Radio, I placed a F-6188 with a BK8000L Bluetooth Module in There, but I'm not happy.
    I'll design a Proper PCB and this A Class Amplifier on it.

    Reply
  • March 10, 2021 at 9:16 pm
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    Why didn't you use a bypass cap? Just curious, it's just a single component even if in this case its not as useful.

    Reply
  • March 10, 2021 at 9:16 pm
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    HI I AM COSTAS ,can you please if posible make an ESP32 internet radio project ,with more detail on the programing of the esp32. thank you

    Reply
  • March 10, 2021 at 9:16 pm
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    this is something I actually want to build really bad. already bough some of the parts wish me luck. but quick question. can you make a guitar amp? like a diy marshall ms-2. there are even schematics online.

    Reply
  • March 10, 2021 at 9:16 pm
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    the ''most inefficient''? don't U mean: most ''efficient''? & what U'r looking 2 design, and build. though, it's U'r channel. U'r video. and U'r business!! the last thing U need, is some dude. sticking his giant chip's in2 the comments……. the main design that U would be looking 2 engineer, would be a hifi audio amp!! U are an ''electronic engineer'' so U will have no problem designing a ''hifi'' headphone amp! personally!! I would find a nice premium hifi amp and deconstruct!!! good luck stranger?

    Reply
  • March 10, 2021 at 9:16 pm
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    I love your videos, BUT FOR THE LOVE OF GOD STOP TRACING OVER THE INK 3-4 TIMES LIKE AN OCD MAN LOL

    And raping the paper with highlighters too! Hahah otherwise great content!

    Reply
  • March 10, 2021 at 9:16 pm
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    I made this circuit but i changed audio and power to female connectors (power to micro usb) and i get a noise. It changes depending on the power source. Not sure how to deal with that

    Reply
  • March 10, 2021 at 9:16 pm
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    I don't know why but I was stuck with class A amplifiers the time you posted the video. May be god heard my prayers! And (saving your reverence) the tutorial was fucking good.

    Reply
  • March 10, 2021 at 9:16 pm
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    Systemic elimination of the physical 3.5 mm headphone jack from smartphones is the worst thing that has happened to the smartphone industry.

    Reply
  • March 10, 2021 at 9:16 pm
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    What if I want to use a battery so I can charge my phone and not drain it? what battery you recommend?

    Reply
  • March 10, 2021 at 9:16 pm
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    Scott,
    Why not taking 4-pole 3,5 mm plug and chassis and connect the 2 mic connections. Now all functionality of the headset will work (call accept button, volume control and microphone)

    Reply
  • March 10, 2021 at 9:16 pm
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    I lost my enthusiasm about electronics for the last two years.This video reminded me how enthusiastic I still am.

    Reply
  • March 10, 2021 at 9:16 pm
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    I would like to get into soldering and building this kind of stuff, while these videos give me good info how to do stuff, would anyone have a video on supplies needed and brand recommendations

    Reply
  • March 10, 2021 at 9:16 pm
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    Hi, will this also work if we use this amplifier with an electret condenser microphone?

    Reply
  • March 10, 2021 at 9:16 pm
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    You forgot to draw the load (O_O)
    You know that since it is a common emitter amplifier, gain can be calculated as Av = – Rc / Re. Right? And what is Rc in your schematic? (The answer is not 130 Ohm)

    I really liked this video, but I think you started on the wrong hypotesis. Ok, I know you wanted to use the simplest schematic possible. But why you haven't used a common collector stage? Or a common emitter, followed by a common collector? Or the simplest one: to use a small 2 channel opamp. This latter is the most understandable for everybody, I think.

    Reply
  • March 10, 2021 at 9:16 pm
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    9:44 You mention cc "pins". There is only 1 CC pin with a plug, the other one is called VCON, and should be left open

    Reply
  • May 13, 2022 at 2:29 pm
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    Ahaa, its pleasant conversation about this article at this place at this web site, I have read all that,
    so now me also commenting at this place.

    Reply

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