ProtoDAC TDA1387 X8 project

[Tim Curtis]

Just an FYI there is an updated Gerber file (Rev E) available.

   

[OnkelPH]

Time to cheer a picture of my current setup. One 2200uf Audio Note and a .47uf Vcap ODAM on the output.

Nice caps  I am also using a tube amp and want to test some higher-grade caps.  Just waiting a good deal. 

What is your power supply that feeds the 3.3V convertor board? 

Thank you!

Nothing fancy at the time. I’ve been using a 3.3v inspired by Gabster
https://youtu.be/m0esUvVu9W8?si=hez2ANebTzlg9pQk

Planing on doing some psu upgrades in the near future, but I’m really enjoying the setup as it is.

[thomaschan]

I am considering to add a tube output similar to Lampucera. Looks rather straight forward. Take out the 10uF output capacitor of the DAC, connect directly to the 6N3P/5670 with a 90 ohm resistor to ground.

Has anyone tried anything like this?

[DRONE7]

From the O/P

Paralleling the TDA1387 increases the output current capability, and allows the practical use of passive I/V (passive components = fixed resistors generate voltage from current). The combination of I2S input and passive I/V allows for a very simple Raspberry Pi based NOS DAC HAT. 

would indicate a I/V device so "**for V-out DACs 250K"

Is how I read it but happy to be corrected :-)

@hifinet would be the answer.

[hifinet]

I have no experience with that circuit. The TDA1387 x8 module is a substitute for a TDA1541A. Just use it that way. The 420R I/V resistors aren't needed. They are only used in ProtoDAC to get the output to line level. Low output resistance will lower distortion.

The beauty of the TDA1387 X8 module compared to an actual TDA1541 is that it is a plug in replacement, sounds very good, uses only a single 5V supply, and doesn't need any of the compensation caps. I believe it can be used in any circuit that uses the TDA1541.

[hifinet]

I would recommend keeping your ProtoDAC intact. Two options. Build the tube board with a TDA1387 X8 module. Use unshielded jumpers from the RPi using I2S resistors.

The other option would be to jumper from the pin 6 and pin 25 leads of the TX2575s to the tube board. The 420R resistors will be in parallel with the 90 ohm on the tube circuit.

[Rio1969]

I got pre5 loaded on my Pi5 and listened to some music with my headphones. The sound is quite good but there is a lot of noise when no music is playing. This weekend I will use a PurePi II to power the ProtoDAC, hopefully that will get rid of the noise.

[hifinet]

Noise is almost always caused by a bad module.

[Rio1969]

Noise is almost always caused by a bad module.

I was assuming that it was from the Pi dirty power supply since I only hear it when there is no music playing.

[hifinet]

There should be no noise. You can double check your solder connections.