Monitor Mixer with DI Box

One of the problem for low budget band online streaming is the mixing part. The biggest challenge is getting the mix right. Why is it hard? Guitar and other instruments have their own amplifier so when you are doing the mix, you would likely decrease the level of these instruments to the main mix. If you are feeding the main mix into your online live feed, chances are these instruments are too silent on the main mix.

This circuit can be use as a headphone amp mixer with built in DI box so you can directly feed the output into the mixer. There are 2 volume knobs, one knob is used for your instrument volume and the other knob can be used as a monitor level feed from the mixer.

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4Ch Mini Stereo Headphone Mixer

4 channel stereo headphone mini mixer 3d render

Here is a simple stereo headphone mixer that can be used for monitoring and mixing 2 sources. A very helpful device for online streaming. How? For example you are playing a keyboard on a band in an online stream and using a headphone as monitor. You can use this to mix the headphone output of you keyboard and headphone output of the streaming mixer so you can hear more of your keyboard.

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500W Amplifier from Eliot Sound Products

I wanted to build this project a long time ago but I have no time to do it. Today I decide to make a PCB design for it. Unfortunately I do not have any time to make the actual prototype. I will post my design so that anyone can build their own prototype.

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2SC5200 2SA1943 Simple Amplifier

If you love to build audio amplifier then you must be familiar with 2SC5200 and 2SA1943 power transistors. They are one of the most used power transistors for power audio amplifiers. While looking for a next project, I found this simple layout on the internet so I decided to make my own version with some few improvements.

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Simple Guitar Headphone amplifier with overdrive and aux input

Here’s a simple guitar headphone guitar amplifier project that you can use for practicing. The headphone amplifier uses a LM386 that can be able output up to 0.7W than can be use also for small speakers. It also has an auxiliary input that can be used to connect your phone or an MP3 player for you to jam and play along with the song you are playing. It has a simple built-in overdrive channel.


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DIY TPA3116D2 100W amplifier with Bluetooth, MP3 and FM for home and car audio

So here’s a little cheap amplifier project that you can build for your home or car audio which only cost you around 600 pesos. 

Bill of Materials

  • TPA3116D2 amplifier module – Php 201 – shopee link
  • Bluetooth/FM/MP3 module – Php 178 – shopee link
  • Enclosure from DEECO – Php 145
  • Others(wires,switches) – Php 50

Total is around 574 pesos only!

Note that power supply is not yet included. I am using it with my hybrid solar power which has an output of 12V which good enough for watching TV and some soft music. Power supply module will cost around 500 pesos, be sure to buy a 24V power supply instead of 12V to have the highest output power possible. At 12V, it can only deliver about half of its power capability. You can use a boost converter to increase the voltage from 12V to 26V to be able to get the maximum power output of this amplifier from a 12V power supply. Boost converter like this one on shopee.

I built it mainly for my home audio but this can also be used for car audio.

Youtube Video build:

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100W Amplifier Project

Here’s a simple 100W amplifier project  that is based on Elliot Sound Products project posted on his website.

Simulation Circuit

For the simulation I used TIP32C and TIP33C for the power transistor because there is no available TIP36C and TIP 35C on simetrix. They are almost the same but the TIP36C and TIP35C is capable of handling more current thus capable of delivering more power.

Simulation Result


PCB Design

PCB design is done using kicad software. It is a free software. The PCB is only 1 layer so it will be easy for most DIYers out there.


  • The size of the 2200uf and 100uf capacitors on the layout are only assumed. Those capacitors comes with different sizes, depending on the manufacturers. Check the actual size first before making the board.
  • Capacitor voltages are 50V.

3D Render

3D render of the board with kicad built in 3D render.


You can use 25Vx2 10A transformer for the supply. The diode can be any rectifier diode rated at least 100V and 12A.


you can download the project on my download page below:

Download Page

200W Amplifier Design

Here’s a 200W amplifier design for your home audio. It is a class AB amplifier. It is capable of delivering more than 200W at 4 ohms.

About the Circuit

There’s nothing special about the circuit, you can find it all over the internet nowadays.


I simulated the circuit using simetrix software. You can download the simulation circuit on our download page so you can play with the circuit and component values. Be mindful on the power of the output transistors.  You can increase output power by adding output transistors but you also need increase the supply voltage. You need to take note that the output transistor TIP3055 and TIP2955 can only have VCE max at 60V. In practice you don’t want to get near to that voltage. The safe supply voltage for this transistor should be around 45V.

PCB Design

The PCB design is simple and used 1 layer PCB only so anyone can build this project easily. You can also download the project on our download page if you want to modify it for your own requirements. My PCB design is simple and there are many rooms for improvements. The size of the filter 1000uf capacitor may be small in actual, you may need to check this before making the board. If you can change it with 2200uf capacitor then that would be better. But take note that this will be bigger capacitor. These capacitor are used to help supply power during big current draw. These high current draw usually happens during bass drum beats, especially if you set your bass to maximum. Supply voltage drops during bass drum beats due to high current draw and power supply output impedance.

These capacitors also helps reduce hum noise by filtering ripple voltage coming from the power supply.

The high current nodes such as power supply and output can be improved by making the trace wider. By making the trace wider on those nodes reduces voltage drops on those trace. This can improve bass performance.

3D Render

3D rendering is build-in on the KiCad software and this software is free!

Power Supply

This circuit can be powered by 24V up to 32V transformer. The transformer should be center tap and at least 8A for single channel.


image credits:


If you want a very reliable design that doesn’t easily fail for years, the key is over designing. Design it to handle 200W and operate it at 100W and expect it to have longer life. This is because there is less stress and heat on each component if it is operating below its power handling. If you have computed that a resistor will consume 0.2W then use a 0.5W resistor or larger. Using a 0.25W resistor will still work but will eventually burn overtime.


You can download the Kicad and simetrix project on our download page