If you are looking to control your audio with arduino, here’s it is. It uses TDA7419 chip which has a lot of features for controlling your audio. It has 4 input selector, bass control, mid control, treble control, loudness control and a built-in 7 band spectrum analyzer.Continue reading “Arduino controlled bass mid treble and input selector with tda7419”
Build this simple 2 band tone control Circuit using transistor with complete schematic and layout you can download.Continue reading “Simple but effective 2 Band Tone Control Circuit using transistor”
Here’s a 3 band tone control with subwoofer output circuit. Take note that the main output are full range. This is not a 2.1 crossover circuit. It is powered with single power supply so you can use a battery or a simple ac/dc power supply.
Here’s a simple circuit you can use to boost more bass from your music. It can be powered by 9V battery or a 12V DC adapter. Take note that this is just basically a 1 band tone control with +- 17dB range at 60Hz bass frequency. You need it to connect before the amplifier input. This can’t be connected directly to speaker. The output of this circuit will be connected to the input of your amplifier and the input of this circuit will be connected to your audio source(i.e. mp3 player).
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.
All range: bass and treble at 0%, 50% and 100%
Bass control (0%-100% at 10% increment)
Treble control (0%-100% at 10% increment)
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.
Frequency response graph of bass and treble at 0%-100% , 10% increment.
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.
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
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
You can download the kicad project file and simetrix simulation file here:
If you love to pump up the bass then this would be great project for your sound system. This is based on my previous tone control design with some modification to give more deeper and louder bass. It is basically the same with modified component values.
ABOUT THE CIRCUIT
The signal amplifier circuit is composed of R1-R4, C1, C2, C7, and Q1. It is configured as common emitter amplifier. It amplifies the signal because it will be attenuated on the next stage. R4 and C1 is used as low pass filter to filter out the low to high frequency ripple voltage of the power supply. It basically cleans the power supplied to the circuit. C2 and C7 is used to remove DC offset from the transistor bias. They are DC blocking capacitors, it passes AC and blocks DC. R2 is used to bias the base of the transistor to set the voltage of the collector to somewhere around the middle. R1 and R3 sets the gain of the amplifier. To increase the gain, decrease R1 or increase R3. Always check the bias levels after changing the value of R1 and/or R3 as this might result to signal distortion.
Simetrix is used in this simulation. A free simulation software for individuals.
The problem with this kind of circuit is that the frequency response is not linear. The graph below is sweep from 10% to 100% bass setting with 10% interval while the treble is set to 50%. As you can see, the response is almost flat around 10% bass setting instead of 50%. It has around 12dB of bass boost at 50% bass setting.
Below is the frequency response of the treble control with the bass set to 50%. There is 12dB bass boost at 50% bass setting. The treble setting start at 10% all the way to 100% at 10% increment.
Adding output buffer
The problem with this circuit is that it changes frequency response with the next stage input impedance. If the amplifier has a volume control, it affect the frequency response.
Here’s a simple 3 band tone control circuit with 1 transistor instead of using opamps. This is using a single 12V supply. The frequency response is not as good as with using an opamp but it is still acceptable provided you just want a way to boost bass, treble, and mid frequencies. The transistor used is a BC549 but this can be replaced by any general purpose NPN transistor like 2N2222, etc.
VR2 = Mid
As expected the response is not as good as what you can get with using an op-amp version but it is good enough for home sound system where you don’t need a very flat response. Each of the controls can affect the whole sound spectrum.
Bass Response at 0%, 25%, 50%, 75% and 100% setting
MID Response at 0%, 25%, 50%, 75% and 100% setting
TREBLE Response at 0%, 25%, 50%, 75% and 100% setting
green – bass = 100%, mid = 50%, treble = 100%
red -100%, mid = 0%, treble = 100%
As for the graph above, the mid setting will greatly affect the treble response. This is still good to use is you just want to boost bass frequency.
MIC Preamp type Circuit
The circuit above can be used for mic preamp. This is a simple but not outstanding. The performance is just ok for low end home audio. But for high performance audio, you should go with opamps especially made for audio applications.
Internet of things is becoming a thing these days. Internet connected gadgets and appliance are becoming more common these days. The advantage is very obvious: you can control these devices using your smartphone with internet browser, specially made apps or with voice command using google assistant. One of the goal of this project is to create a tone control with bass, mid, treble and source selector that can be controlled via smartphone or laptop with an internet browser. You can also develop an app for this but I haven’t have time to do so.
About the Circuit
The heart of the circuit is the NODEMCU – a wifi module that can be programmed using arduino IDE. If you are already familiar with arduino then this can be easy for you. It is connected to a 1.44 inch tft lcd with ILI9163 driver. The preamp is based on TDA7419, this is a digitally controlled tone control via I2C. This features bass, mid, and treble controls with adjustable frequency. This also has a 7 band spectrum analyzer which is better than using an FFT on arduino. This makes it easier for the programming since you only need to read an analog pin directly rather than doing the FFT calculations on arduino which is a bit of a headache to do.
The TDA7419 is powered with 8V so an 8V regulator 7808 is needed. It is also used to power the Nodemcu for wider operating voltage (most nodemcu can only operate up to 10V only). 7808 regulator can operate up to 35V input voltage. You can also use any regulator as long as it has 8V output and a sufficient output current.
As you can see on the schematic, there is only 1 left GPIO on the nodemcu which is the D3. There is still GPIO9 and GPIO10 but many claims that they are not usable and are not recommended to use. This is the reason why I am not continuing this project with this kind of display. By using an I2C display, I can free up 5 GPIO’s that can be used for buttons.
About the Software
The software is developed using arduino IDE. Note that this is not very well developed, there are many rooms for improvement. I won’t be improving this software further because I decided to replace the display with an OLED I2C desplay. The reason is that the ILI9163 TFT display needs more GPIO and nodemcu has very limited GPIO. Using an I2C display will free up GPIO for other functions.
The device will not start the initialization of the TDA7419 without a wifi connection. Once it established a wifi connection, it will then go to initialization on the system. That is how I designed it, because it was just a quick programming for proof of concept only. Like what I said – there are many room for improvements here. I just posted this project for those who want to have a quick start. For the next version of this project I will be using an OLED display to be able to use the 5 GPIO for buttons and other functions.
For the prototype, I used LM317 instead of the 7808 voltage regulator, because that’s what is readily available on my stocks. 🙂
The IP address is displayed on the LCD. This is entered on your web browser to access the controls. Take note that you have to connect on same wifi to be able to access the device.
Controlling with web browser
This is a simple webpage I made which can be improved further. The basic functions are there so you can use it as is if you prefer. There are many rooms for improvement here.
You can download the source code on the download page