Category: Audio

Alexan Overdrive FX kit review

So I purchased a guitar overdrive effects kit from Alexan just for fun. If you are looking for a cheap DIY effects for your guitar, this one is for you.

Schematic

The design is not a true-bypass configuration, meaning the signal is still passing on the buffer circuit in bypass mode. What is bad about that? Well the buffer circuit cuts of some of the low frequencies of your signal and it also adds some noise to it.

At bypass mode, the low frequency cut off is just small and negligible. It cuts -3dB at around 30Hz.

Tone Control Response

Below is the simulation I made and compared it to Ibanez Tube Screamer FX pedal. Volume and gain set to maximum and the tone control set to 0%, 50% and 100%. As you can see, gain on the alexan overdrive is lower due to passive tone control design used. It also has more aggressive low frequency roll-off, which mean the alexan has thinner sound.

On the other hand, alexan has more gain on the overdrive circuit because it uses a 1M gain potentiometer rather than the 500k used in ibanez tube screamer. But do you need that high gain? I don’t think so, higher gain means higher noise.

Mic Preamp With bass treble Tone Control for videoke

If you are looking for a mic preamp with bass and treble control, you may consider this one. I designed it for my future mixer build. I am planning to build one someday when I am not too busy.

ABOUT THE CIRCUIT

The circuit is only on design stage, not yet done any prototype but it is working on my simulation. This is an improved version of the preamp on my audio mixer design I posted.

The rolloff on the 10k-20kHz range is caused by the capacitor C8. This is done to make sure the system will not allow any radio frequency to pass especially AM radio signals. If you want that roll-off to be more aggressive, you can increase it. Treble frequency is set by C3 and C4 while C2 is for setting the bass frequency. Increasing those capacitor values will decrease the frequency. For instance you want the bass to have more boost on the lower end frequency, just increase the value of C2.

Gain is set by R1, if you want more gain, increase R1 value. Potentiometer used are 100k, using 50k or lower will decrease the boost and cut range by around 3dB.

Simulation Results

All range: bass and treble at 0%, 50% and 100%

 

Bass control (0%-100% at 10% increment)

 

Treble control (0%-100% at 10% increment)

 

Bass Guitar 2 band eq active preamp circuit

Here’s a simple 2 band Equalizer circuit for your bass guitar. Can be powered by 9V battery.

About the circuit

The circuit it made up with 2 opamps from TL072 IC. You can use OPA2272 for better performance. The volume control is not included on the circuit but it is connected after the pickup. VR1 is a trimmer resistor meaning it is only for gain trimming which is adjusted once and forget it. you can replace it with a fixed resistor once you determine the best value.

 

Simulation Result

Frequency response graph of bass and treble at 0%-100% , 10% increment.

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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(Please support my channel and subscribe!)

2 Band Tone Control

Here’s an improve tone control with 12dB boost on 80Hz for better super bass experience.

About the Circuit

The circuit is made up of 2 opamps TL072. This can be changed to other general purpose opamps like LM358. First stage opamp gain is set to 1, if you need more gain, you will need to decrease R2. If you want to use it for Mic, use 1k for R2.

Take note that there is no capacitor in series with the output, this is only for simulation, in reality you will need to add capacitor at the output to cancel out the DC offset on the output.

Want more Bass?

This circuit can already deliver +12dB boost at 80Hz but if that is not enough for you, you may want to decrease value of R3 and R4 for higher bass boost. Decreasing it to 3.3k will give you a bass boost of around 17dB at 80Hz! That would be too much and take note that you may need more power for that.

 

Simulation

Flat response ( bass and treble set to 50%)

there is roll off at both ends but it is only around -1dB which is fine. The roll off on the 20kHz is intended to reduce AM interference. This can be reduced by reducing C7 value. While the roll off at the lower end is needed to reduce subwoofer excessive movement. For music listening, the 20Hz to around 50Hz frequency is not important because almost no instrument is playing on that range of frequency. You can further decrease that roll off at 20Hz by decreasing value of C1.

100% Bass and Treble

 

0% Bass and 0% Treble Vs Set to both maximum

 

 

PCB Design

Please do take note that the simulation part numbering is not the same on the PCB part numbering. In example R1 on the simetrix simulation file is not the same R1 on the PCB file.

For PCB design, I used only single layer PCB so it will be easy to build for anyone. But in order to do this, I needed to add some 0 ohm resistors as jumpers. Just use wires for these 0 ohm resistors, these are R13, R14 and R20 on the schematic.

 

3D Render from Kicad Software

 

Downloads

You can download the kicad project file and simetrix simulation file here:

 



Simple USB powered Audio Mic Mixer

Here’s a simple Mic mixer that can be Powered with 5V. There is currently 3 channels on the circuit but you can add more if needed.

About the Circuit

The circuit is made up with BJT common emitter configuration. OPAMPS that can operate at low voltage are hard to find at a local electronic stores. The very common TL072 opamps can still operate at 5V at a very limited output voltage swing.

The circuit provides ~29dB gain, you can reduce that gain by increasing the value of the emitter resistors(R8,R9, and R11).

R3 and C1 is a filter for the power supply. C1 can be increased to reduce the noise if your power supply is noisy. R3 can also be increase up to around 100 ohms for better filtering.

You can connect this circuit to the USB audio interface circuit in this post so you can have this connected to you PC for recording.

Simulation

On the simulation below I used waveform generator with sinewave output at 100mV at frequencies 100Hz, 200Hz and 500Hz respectively. The volume setting is set at 30%, 10% and 10% respectively.

Build this Simple but amazing USB Audio interface for only $5

In case you want to connect your audio mixer or electronic piano or any other line level audio equipments to your computer or laptop for recording, here is a simple USB audio interface circuit that does the job. It is based of PCM29XX IC from TI. This is used in many analog audio mixers with usb interface such as the Behringer Xenyx USB mixer series.

About USB audio interface circuit

This circuit is USB powered. The IC has 16bit delta sigma ADC and DAC and capable of up to 48kHz sampling rate. it has stereo line level input and outputs.The crystal needed is 12MHz.

 

Quick PCB design

Here is a simple PCB layout that I designed using kicad software.

3D Render

simple usb audio interface PCB design
simple usb audio interface PCB design

Want to have a copy of the Kicad design? Just like my facebook page and send me a message. thanks for visiting… 🙂

Prototype

Since I needed this circuit for my recording may piano and guitar covers, I built my own using universal PCB. This is what I used on my guitar and piano covers on my youtube channel here. 

At first time try, I am having problem with it. Windows shows an error message “Device not recognized” when I plug this to my Laptop’s USB port. Upon hours of troubleshooting, I found out that C13 and C14 is causing this issue. These are the capacitors connected to crystal oscillator. When I tried to removed these capacitors, the issue now gone. I tried to lower the value from 22pf to 15pf but it didn’t solve the issue. I also tried 5pf but same thing happens. For this prototype I just removed C13 and C14. Maybe because there is parasitic capacitance on the board that I used.

There’s no need for drivers, it installs automatically when you plug it in. It has 16bit ADC/DAC with up to 48kHz sampling which is good enough for recording. 16bit/48kHz might not sound great but it is actually good. This chip is used by Behringer on some of their Xenyx USB mixer and also on their cheap usb audio interface. The audio quality is not the best but it is better than those cheap USB sound card on the market. This is good enough for recording for you youtube content. 

Video

Here is the actual video of my prototype in action.

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USB audio interface Parts list

RefValuePart
C11u16V electrolytic capacitor
C20.1uceramic capacitor
C34.7u16V electrolytic capacitor
C44.7u16V electrolytic capacitor
C51u16V electrolytic capacitor
C61u16V electrolytic capacitor
C71u16V electrolytic capacitor
C81u16V electrolytic capacitor
C91u16V electrolytic capacitor
C101u16V electrolytic capacitor
C114.7u16V electrolytic capacitor
C124.7u16V electrolytic capacitor
C1322pceramic capacitor
C1422pceramic capacitor
D1LED:LED
J1USB_B:USB connector
J2Input3pin JST connector
J3output3pin JST connector
R12.2 ohmsResistor SMD or 1/4W or 1/8W
R21MResistor SMD or 1/4W or 1/8W
R31MResistor SMD or 1/4W or 1/8W
R41.5kResistor SMD or 1/4W or 1/8W
R522 ohmsResistor SMD or 1/4W or 1/8W
R622 ohmsResistor SMD or 1/4W or 1/8W
R71MResistor SMD or 1/4W or 1/8W
R81MResistor SMD or 1/4W or 1/8W
R91MResistor SMD or 1/4W or 1/8W
R10220 ohmsResistor SMD or 1/4W or 1/8W
U1PCM2902CUSB interface IC
X1CRYSTAL12MHz Crystal

The parts list does not include input and output connectors, you may opt to use RCA or phone jack connector.

I am planning to build an improve version of this device and sell it online so stay tuned! Subscribe to my youtube channel and facebook page to keep you updated! 🙂

DIY DI Box v3

I just noticed that many of my visitors are searching for DIY DI Box so I decided to make another design project for DI Box. This will be powered by a 9-15V AC/DC adapter or a 9V battery.

About the Circuit

The circuit is basically made up of 2 opamps, 1 is configured as a buffer and the other one is configured as an inverting opamp.

R2 and R3 is used as a voltage divider to provide 1/2VCC for the opamp. This is needed for single supply operation of opamp. At single supply, the output of the opamp cannot swing at negative voltage so the output of the opamp is offset to 1/2VCC so the output can swing below 1/2VCC for negative voltage and above 1/2VCC for positive voltage swing. at the output stage, a capacitor is used to remove the DC offset and output only the AC voltage. C5 is used to filter the 1/2VCC from the voltage divider R2 and R3. R1 and C1 is used to filter the supply. This is used to filter out the 60Hz/120Hz line noise on the supply. If you are using a battery, you can just remove R1 instead. Potentiometer value can be 100k to 1M. I used RCA connector simply because I can’t find any Audio phone jack on my library and I don’t have time to search for it.haha

C6 and C7 voltage rating should be at least 50V, this is to protect the cap when phantom power is accidentally turned on. Other capacitors can be rated 16V and above.

Phantom Powered DI Box

If you want it to be powered via Phantom power of mixer, you can check this version of my DI Box here: https://tataylino.com/diy-di-box/
You just need a 1/2W 6.8k resistor and a 15-30V zener.

PCB Design

PCB design is made with KiCad, a free open source software. Designed with 1 layer PCB for easy DIY at home.

3D Render

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

Schematic

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.

NOTES:

  • 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.

POWER SUPPLY

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

DOWNLOADS

you can download the project on my download page below:



Download Page

Simple 2 way crossover project

Here’s a active 2 way simple crossover project for you.

About the circuit

The Circuit is simple and uses only 3 opamps per channel.

Crossover frequency is set around 234Hz. The cutoff(crossover) frequency can be changed for your requirement. The formula for the crossover frequency indicated below:

C4 is used to block DC voltage at the input. Since the input impedance of the circuit is very low, C4 value can be as low as 0.022uF. But for my final circuit I have used 0.1uF.

R3 and R4 are voltage divider used to provide half VDD voltage for the op amps. This is required because the power supply has no negative voltage. Without this, the output will be clip on negative cycle. C3 is just a filter capacitor to clean the voltage produced by the R3 and R4 divider. R5 is used to set the input of the input buffer to half VDD, 1Meg value is used so it will have little effect on the input impedance.

Simulation

Simulation result

As expected, the crossover frequency is around 234Hz.

PCB

For PCB design, I made it single layer so most of the DIYers can easily make their own PCB. As usual I used KiCad to design the PCB which is a free software. Resistors on the VDD are just jumpers(that is why it has value = 0).

J1 – Right input

J2 – Left input

J4 – Low Right output

J5 – Low Left output

J6 – High Right output

J7 – High Left output

J3 – Power Supply (12V – 24V)

3D Render

3D render using KiCad…

DOWNLOADS:

This project can be downloaded for you own personal use. If you want to use this for commercial use, please contact me on my Facebook page for licensing. 🙂

Please don’t forget to like my facebook page. 🙂

Download page

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