Sonica 1 – Headphone Amplifier With TPA6120A Part II – PCB Assembly and Rebuild

After some waiting for Sonica 1’s PCB they have arrived. As usual, the quality was very good. I had made a few mistakes, but nothing serious. I will take a few minutes to explain what I had to fix and how the assembly and rebuild of the original amplifier went. The end result was as expected, no change in sound quality.

Part I of this article included my complaint that the transformer wires’ sleeving had melted at room temperature. The amplifier was never left in direct sunlight for long, it has never heated up during operation either. Apparently Indel had chosen the worst possible material for the sleeving. Some of the photos in the gallery below show the situation. Even the connector on the PCB was covered with black sticky substance from the sleeving. Fortunately the connection was good and I never had problem because of this. That is why I never knew it’s melting before I opened the enclosure for redesign.

As I mentioned in the beginning, it took quite some time for the PCBs to arrive from China, but it was worth it. The quality is very good as usual with EasyEDA. Unfortunately I had made a few minor mistakes with the design. For example the mounting holes for the regulators’ heatsinks were too small. I didn’t pay enough attention when designing the footprints. That was easily fixable by filing the mounting pins of the heatsinks. The footprints for the 100nF WIMA capacitors were also wrong. The pin spacing was 2mm instead of 2.5mm, but that was not a big issue and I soldered those easily. The last issue was the mains connector. It is documented as 250V AC/DC connector, but its pins are too close according to safety standards. To fix that I removed the middle pin, because I am using the amplifier with 230V and also removed the copper on the PCB that was meant for this pin. Now it is safe. I will fix those issues and update the files in Part I of this article for anyone who might want to build this amplifier.

Recently my ASUS Xonar U7 external sound card decided to die (DSP issue) and I had to find a new one. Some research brought me to the decision to buy TOPPING D30 External Audio DAC. It is a Chinese product with very good quality. High quality components, good PCB layout and schematic design. Definitely good value for the money. As some reviewers have described it, this DAC is completely transparent. It is like it is not in the signal path at all. No sound coloration, no character. It just decodes and let’s the next component in the circuit take over from there. I am really happy with that purchase.

Sonica 1 sounds the same as the old design as expected. At least there is no change I can hear so far. TPA6120A2 is known to be a little light on the bass and my amplifier is not an exception. Other than that it doesn’t have much of a character similar to the DAC. Some might say that is boring, but I like it. If I want specific sound, I could always enable the equalizer in Foobar.

You can see that the final look of the amplifier is the same as it was before except the volume knob, which I replaced with larger and better looking one. Internally it looks much better as you can see from the photos.

Last but not least the headphones are also new, Beyerdynamic T5P 2nd generation. Those are absolutely great for my personal taste. I’ve heard them before at Munich HiEnd Expo a couple of years ago. Actually, it was T1 and T5P AK. Both sounded so pleasing, I didn’t want to stop listening. The 2nd generation has a better design and a little different sound. Some say it has too much bass, others say they are just perfect. I think I’m more like the second group.

Well, let’s finish with the photo gallery:


I am sure the license note on the right side of this web page is well visible, but let me remind you the following:

This project has been developed and released as an open source by Stefan Penov.
Licensed under Creative Commonns Attribution-NonCommercial-ShareAlike 4.0 License:
Under this license you as a user are free to share and adapt this work under the following terms:
>>> Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
>>> NonCommercial — You may not use the material for commercial purposes.
>>> ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.
>>> No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.

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