DIY Portable Size TDA1541A USB DAC (Part 1)

This is the first part about DIY portable size USB DAC TDA1541A with the headphones amplifier included. The second part can be find here

I have many awesome DAC that I have collected from early this year. The latest built DAC that I listen so much is this PCM56P here as part of my home stereo integrated amplifier. I don't to add another one until my conversation with my friends started. He has brand new TDA1541A IC that willing to sell to me. So here let's the new DAC project begin.

You may already know here that the Nakamichi DAC-101 is using dual TDA1541A S1. This DAC is superior in term of sound quality and there is no other DAC on my list so far that has this sweet and smooth sounding. That is why for this new build TDA1541A DAC should be different with the others I had before.

Then I using a sketch paper, drawing the possible layout to make a TDA1541A DAC with USB input and a headphones amplifier as compact as possible. I am quite surprise this TDA1541A is very simple to build and it can be done in this compact size.

I can say this is the smallest yet the most compact TDA1541A DAC with USB input and headphones amplifier ever built. The overall casing size is only 12 cm x 7 cm. This is the born of portable size TDA1541A DAC.

First of all, I wonder what in your opinion by looking this TDA1541A IC as the photo above?

Is is legit? This is also my question after receiving this IC from my friends who sold to me. My others friend said this is legit, the others said it is not. So I don't want to speculate about it and let the project begin.

My previous built DAC are mostly using SPDIF as digital input. It is using the CS8412 as the digital receiver. Sadly no one sell this IC anymore. This IC is already discontinued from many years ago.

So in this new DAC building, I will using PCM2706 USB to I2S converter. This is the smallest module board I can find. The USB is auto detect by my Android phone with the UAPP installed on it. This USB receiver also detect when I connecting to my laptop. The output is I2S that can connect directly to the TDA1541A.

Then I start populated all the components in the board. The first components are the IC regulators. This TDA1541A required 3 voltage, they are +5v, -5v, and -15v. To fulfilled this requirement, I using the fixed IC regulator 7805, 7905, and 7915. They are simple to use because no need extra components. I put extra one IC 7805 regulator to supply the PCM2706 USB to I2S module. Then another 7815 for +15v output that will supply to the op-amps along with the -15v taken from 7915.

The main power supply is from single AC 15 volt supply. Then it convert to dual DC voltage, the same method when I applied in the PCM56P DAC before.

At this point, the components start to fill to the entire board. Those are PCM1706 digital receiver, TDA1541A DAC, voltage regulators and the op-amps for the IV and LPF section.

The schematic for this analog stages are the popular one taken from the internet. The simple IV converter using 1k and 220pf at inverted input op-amp. The LPF is calculated as the 2nd order above 40 kHz.

This is the finished board.

For the headphones amplifier is using the same schematic as the CMOY headphones amplifier.

The only missing in this board is the mini jack for headphones output. I still order it and need few more weeks to come.

I also build the new power adaptor using EI transformer rated 15VA. The secondary output from this transformer is 15 volt AC.

I checked all the voltage, they are correct as per IC requirements. Then it is time to test this TDA1541A DAC.

It is works perfectly since the first time I power it ON.

I only concern here is on the PCM2706. The power supply from DAC going to the phone and charge the phone battery. This charging makes one 7805 regulator in the DAC getting so much load. This also cause the smartphone UAPP installed become very sluggish to detect this USB DAC.

Thankfully I got the solution by connecting the phone first before turn ON the DAC. This makes the UAPP detect the PCM2706 as USB DAC instantly. This method also wont get charged the smartphone battery from the DAC.

The others solution is tear down the micro USB cable that attach to this PCM2706 USB module and cut the red cable that act as +5 volt supply from the battery of the smartphone.

At this point, this portable size TDA1541A DAC is finished. Not completely done actually since I am still waiting few parts to come.

I test the sound quality from this DAC and it is sound good.

I have another issue. It is about the regulator IC heat issue. Honestly I missed calculating this heat when designing the board at the first time. I think this DAC current will be the same as my previous DAC build using PCM56P. But it is not. When this DAC operate, it draw so much current. For more than 3 minute, the regulator start to getting warm. Then, few moment later, it is become warmer and warmer until impossible to touch by my hands. This is because no heat dissipation on those IC’s. This can cause the regulator fail and directly effect to the IC in this DAC. Especially the precious TDA1541A can be broken if this regulator IC fail.

So this is the end of the first part. The updates will continue on the next post.

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.