My Arcam Black Box (via eBay) v.1 has recently died. After the inspection, it appeared that TDA1541 got faulty. The way how did it end fully matches the description of other guys on diyaudio.com forum. It’s quite weird. I was playing around and tried new cathode bypass capacitors in my SRRP stage, which was directly connected to TDA1541 (via eBay). Of course, everything was off during re-soldering etc. However, when I switched on, the sound was distorted and it started to deteriorate. At the end, there was only the buzz and no any sound… Anyway, TDA1541 chip from eBay is on the way.
That brought me to the idea that I need to look for some backup option, just in case in the future.
After some browsing, I ended up with TDA1543 (via eBay) audio dac chip, which is still widely and cheaply available on eBay. Also, I read different artciles about this chip, including on Lampizator’s website about AHDAC with TDA1543 chip. According to it “Finally I threw the resistor away and bingo – music explodes with 3d space and full energy.” Ok, Lampizator suggest not to use the resistor as IV(IU) converter as it does not sound good.
I already have very pleasantly sounding SRRP stage. In this case, I would have to build the digital part (including the dac chip), SPDIF receiver (I had CS8412 (via eBay) from older times) and their power supplies.
TDA1543 project from Russia
While browsing, I came across extremely interesting TDA1543 project from Николай Штаюр. The title says “Entry level dac”. Fair enough. TDA1543 is not indented to beat the top level of high-end but… it might sound reasonably well. Nikolaj explains quite many technical details, which matter and make the impact in sound production. I am not going to repeat everything here, only some aspects of his project. I strongly encourage to read the article yourself even with Google Translate if you cannot understand Russian language. It is really very informative article on how used electronic solutions/decisions translate into the sound quality.
In this circuit, there is one quite interesting thing and it is the power supply part for analog signal section. First, the constant current sources are used (based on LM317 (via eBay) regulator). Then, the voltage shunts (based on TIP transistor) follow them. Well, it looks quite intriguing and I would like to repeat something similar to such power section. There is another interesting detail. I checked TDA1543 (via eBay) datasheet looking for power supply ripple rejection (PSRR) or similar parameter. Unfortunately, none was given. Only one comment was that power supply ripple should be within 1%, which suggests that PSRR is pretty low and very good quality power supply needs to be used together.
TDA1543 DAC for advanced listeners
Another Nikolaj’s TDA1543 project, which description can be found here. The circuit is shown below.
There are some differences, speaking about the power supply for analog signal section. Basically, a voltage shunt regulator follows another voltage regulator. Also, the IRF610(via eBay) transistors were replaced by the bipolar type. The sound differences are described in the article itself.
Another PSU from Audioexpress journal
I came across another article on Audioexpress journal’s website. Similar ideas to Nikolaj’s are discussed here too.
We see a similar structure of PSU like in the v1 of Nikolaj’s circuit. Only, the discrete components (MOSFET) are used to build the constant current source. After that, a shunt regulator follows.
In summary, I think it’s a pretty good collection of circuit ideas for my TDA1543 (via eBay) audio DAC construction. I only need to wait for all components to arrive and I can start building it.