Build Your Own Portable TDA1543 USB DAC Headphone Amplifier

Happy new year 2022!

This is my first post in this year dedicated for everyone who want to build a DAC. I am pretty sure that most of my previous DAC project are not for beginner. It is complicated and need lots experiment when built them. This would be a barrier for the new comers to enter in this hobby, especially when the cost of those DAC IC are expensive, then making a DAC like that for the first time is highly risk to fail.

Then, I was thinking about a simple and cheap DAC to build. This should be reliable and good sounding DAC of course. Then my choice for this USB DAC + headphone amplifier project is TDA1543 DAC. This is cheap DAC IC and still available today. So let's heat the iron:)

Early disclaimer: although this project is considerably for beginner, note should be taken that the beginner mentioned here is at least should have basic electronic knowledge and experience. Used to work with other electronic project especially in the power supply or others audio electronic. Caution should be made when dealing with small electronic components and soldering iron.

As always, like on my footers disclaimer, I am not responsible for any failure, any cost, anything loss when dealing with this project.

The reason I put this TDA1543 in this portable DAC project is because this IC is the cheapest multibit DAC. I still can get as low as US$2 each. This TDA1543 is also very simple to build and it sound good. Please make sure you got the original IC.

Since most of the smartphones eliminate the headphone jack, then using the USB out to the external DAC like this will be a better solution. The external DAC using this TDA1543 will also improve the sound quality. This USB DAC can also connect to Windows PC or laptops with Windows 7 OS or later without needed any additional software.

This is the complete schematic of this project.

To make this schematic easy to understand, I split it into 4 segments.

The first segment is the battery charger and low battery indicator. I am using TP5100 2S 18650 battery charger module which the output set to 8,4 volt. This module is small and built in full/charging LED indicator.

The second segment is the USB receiver based on PCM2706 USB to I2S module converter. This is a very small module that convert the USB signal from the micro USB input to I2S output required in TDA1543 DAC.

The third segment is stereo DAC circuit using TDA1543. The IV converter is using only a resistor for each channel. This is the simplest IV section compare if using op-amp.

Then the last segment is the stereo headphone amplifier using AD823 op-amp. You can substitute to others op-amps such as 5532, OP275, or 4556, but the result may vary. Using this AD823 in this project is more reliable, because it designed to use with single supply instead of dual differential voltage. It is also low pop noise during ON/OFF, capable as low as 3 volt supply, and the most important things is this op-amp sound good.

Before I begin, I always prepare the casing and the PCB board first. I am using small casing with the dimension about 12 cm x 7,5 cm x 3 cm. This size is very suitable to the recent smartphone size, so they can be stacked together.

I start to put the batteries on the board first. The next step is populated the input output components such as USB receiver module, 3.5 mm headphone jack, LED indicator, and the stereo potentiometer The input output components will align to holes at the casing, so they will look flush on it.

Those critical components need to put in the first place before the main components such as DAC IC and the headphone amplifier.

As you can see on above photo, the low battery indicator on top left is built by using TL431. The trim-pot is to adjust the minimum voltage input detect to the TL431. The working principal is like this, you may know the optimal working voltage from two 18650 lithium battery is vary from 6 volt to 8.4 volt. So, what I want is the LED will be dim once the battery voltage has going down on certain point set by the trim-pot. In this project, I set the trim-pot when the batteries goes to 7 volt. At that point, the LED will going from bright to dim. It means the batteries need to recharge. 

After the batteries indicator circuit is the 7805 regulator for PCM2706 USB to I2S module. It require 5 volt input from the batteries voltage.

The next circuit after the USB to I2S module is the 8 pin IC socket for TDA1543. This DAC power can be supplied directly from the batteries. This DAC IC can handle maximum 9 volt DC voltage without worries damaging it.

The only concern is the IV resistors and V-ref resistor value. I had playing with several value and for this portable application, the optimum resistors value are stated on the schematic above. The 2 kilo ohm trim-pot for the VREF resistor is still using here just in case I can to redial it in the future. You can do the same like mine if you wondering how this VREF adjustment effect to the sound quality.

The connection between PCM2706 USB to I2S module to TDA1543 are made with only 3 connection. They are LRCK, DATA and BCK connected respectively as the schematic above.

Finished with the DAC, I starting to put the 8 pin IC socket for AD823 op-amp.

Nothing new under the sun. Means I also using this headphone amplifier schematic from the original AD823 datasheet. It measured well from the Analog Device engineers and surprisingly sounds good. The only changed I made is the resistors divider network at the input pins of the op-amp. Because this amplifier is now working on higher voltage than the actual recommendation in schematic bellow, so I need to put another 100k resistors on positive polarity on each channel input pins.

You may also see my note optional on the schematic above, which adding the 100nF capacitors can improve to the smoother audio response.

The last module I put here is the charging module. This TP5100 charging module capable to charge 2 unit 18650 batteries at the same time. I tested this charger module using 12 volt 2 ampere wall adapter and it works perfectly.

The LED indicator going RED when the charges begin and going blue when full. On my listening test, from maximum charged batteries down to 7 volt, this unit withstand up to 10 hours. The recharge only takes maximum 3 hours until the batteries fully charged.

After finished all of the connection above, I checked the voltage on every sockets pin, especially the voltage should be correct in the polarity corresponding to the IC's pin. If all of them are correct as per schematic, this unit will be instantly working flawlessly.

Please note despite the building cost can be much more cheaper than US$50, but I don't recommend to using cheap components. Not because it will sound not as good as intended, but cheap components easily break and not reliable. For example, you can using less than a cent for a resistor, but spending a little more will be more beneficial. I am using affordable Vishay resistor for only 2 cents each. The capacitors using in this project are all 220 uF Panasonic FC which cost same as the resistor. At this point, the components quality are already very good.

The only components that takes the cost climb high is the batteries. Finding good and affordable 18650 type batteries is quite difficult. What I am using here is a used batteries dismantled from old laptop. They still working good.

The other components such as aluminum casing, PCM2706 USB to I2S module, ALPS switched potentiometer are second expensive components after the batteries. The total components cost will not exceeding US$50.

The main question after finish building this project is how does it sound?

In my opinion, it is simply amazing. I hardly spot any bad sound or noise in this portable DAC. This portable DAC is very reliable, yet easy to use just like a commercial product. You may really like it just because it made by your own, but the sound quality can be compete with much more expensive branded portable DAC out there. Remember the TDA1543 is still a multibit DAC which have a warm touch in the sound quality. It is a difference sound signature compare to the typical delta sigma DAC.

In this test, I am using Android mobile phone with UAPP installed, AIFF audio format ripped from CD's using iTunes, modified micro USB to USB C cable by cut the red cable for +5 volt supply, so the DAC batteries wont charge to the phones. The headphone that I am using is the Koss KPH-30i.

Additional information

Maybe there are several question you might want to ask before having enough guts to build this project. I will try to share as much information as I can.

Resistors value are not critical. You may using 20% variance from schematic value. For example, the feedback resistor in AD823 required 5k ohm. You might difficult to find one and you can using 5k6 or 5k1 to substitute without any problem at all.

The capacitor value may also vary. I am using 220uF 25v capacitors for all, including the output capacitors. You can use as low as 100uF 10v up to 470uF 25v. The bigger the value, the better the sound sometimes, but for sure the bigger the size.

Battery Management System (BMS) module doesn't required here. The reason for this is because it degrade the sound quality. Previously I had use it then I remove it.

The other reason is BMS function theoretically will distribute the voltage to each batteries during charging, this will protect the individual batteries from over-charged. But I don't see this benefit at all in the BMS module I purchased here.

I relocate the charging module to top of the board. It is put besides the USB module. The reason is simply the LED charging indicator more visible in this new position. The large hole of USB input is also become the window for me to check the LED status on each modules. 

Disclaimer: Any statement and photos in this article are not allowed to copy or publish without written permission from the writer. Any injury or loss from following tips in this article is not under writer responsibility.