ProtoDAC TDA1387 X8 project

[hifinet]

The confusion due to the fact that they would be called DAC plus Amp or integrated amp in the traditional audio world. 

The JustBoom designation of the audio amp as "Amp", and DAC plus Amp as "Amp HAT", seems consistent with this. At least HAT hints that it gets GPIO input, and must have a DAC.

HiFiBerry's Amp meaning DAC plus Amp and AAmp as an analog amp seems to be inconsistent with traditional audio.  

"The HiFiBerry Amp is a high-quality, highly efficient Class-D power amplifier for the Raspberry Pi." It's actually more than just a power amp. 

"The Amp100 is a combination of the DAC2Pro circuit with a powerful 100W per channel stereo amplifier." Much better description.

[hifinet]

Hi Mark, hi everybody, 
This is not related to the component shortage: I wish to informe you that I have seen a version of "parallel TDA1387" made with 4 IC only, but with discrete components instead of SMD components. I am trying  to buy a couple of them (to be wired in parallel) to test if those capacitors "sound" better. At the moment I have not been lucky finding them: may be that your chinese supplier knows how to find them, or somebody else, in the forum, can help in this way.
Best regards and thanks,
Francesco

I happened to come across the TDA1387 X4 module on Tabao and AliExpress. It is associated with JOSAUDIO (http://www.josaudio.com), a Chinese company that produced a TDA1541 DAC.  Here is another seller.

[hifinet]

I tried the TX2352 (Vishay S-foil) I/V resistors in ProtoDAC, and the TX2575 have significantly better sound quality and are definitely worth the few dollars extra. The TX2575 sound more open, detailed and have greater high frequency extension. The TX2352 probably have other problems in comparison, but I couldn't wait to get them out of there. At first, I thought there might be something else wrong with the test bed ProtoDAC (with C3/C4 and I/V resistors sockets), but after installing the TX2575, the sound has returned to normal.

[Skip Pack]

Thanks for running that test and  passing your impressions along.

[Gaspar74]

Hi, Just finished my build of the protodac, I got a kit from Hifinet and hes been extremely helpful in getting this up and running. I am looking for some type of enclosure to put it all in. Does anyone have a good source for small enclosures for dacs aside from Ebay and Ali. I have built a few amps, IcePower as well as Texas instruments new Class D chip and got cases that way. Took quite while to get though. Also if I was wanting to power the Pi and the Dac seperately, how would I go about doing this. TY.

[hifinet]

Mentioned in earlier posts are the Geekworm, which is not a full enclosure case, but looks OK and is very inexpensive. Other ones posted here.

Powering the RPi and DAC separately can be done in a couple of ways. You can use a stacking header (or here) to connect to ProtoDAC and remove pins 2 and 4. That disconnects GPIO power from the ProtoDAC. Then connect power to the 5V and GND pads between the RCA jacks on the ProtoDAC.

A permanent method is to pull GPIO header pins 2 and 4 before soldering the header to ProtoDAC.

If you are using an Allo Kali (and probably other reclockers), there is a jumper (labeled SBC) on the Kali does the same thing. Power provided to the Kali provides power to the ProtoDAC.

[ECELO]

I have recovered 99% of the components, but I am unable to recover the Charcroft z-foil 430r because they are out of stock, while for the TX2575 which can be ordered on the Texas site the shipping costs for Europe are prohibitive. In Charcroft there are CART 390R00B: 390R 0.4W Charcroft Z-Foil Resistor, but I read that the value would be too low. What hi-end alternatives available in the EU could I use? Thanks in advance for your reply.

[dwhacks]

So I'm new to the CamillaDSP and other signal processing part of moode, does it effect all playback? will the polarity inversion effect Airplay and Spotify also? I just want to make sure the polarity is correct, but honestly I'm not really sure if my system has anything else inverting.

Is there a good way to test this at the speakers?

[hifinet]

I have recovered 99% of the components, but I am unable to recover the Charcroft z-foil 430r because they are out of stock, while for the TX2575 which can be ordered on the Texas site the shipping costs for Europe are prohibitive. In Charcroft there are CART 390R00B: 390R 0.4W Charcroft Z-Foil Resistor, but I read that the value would be too low. What hi-end alternatives available in the EU could I use? Thanks in advance for your reply.

You can use the 390R and if you have a preamp it won't be a problem at all. As the resistance of the I/V resistor decreases, the output voltage will decrease. With 430R the 0dB output is typically measures around 1.3 Vrms. Based on this, with 390R the calculated output voltage at 0dB will be 1.18 Vrms, which is less than 1dB difference.

You may need to increase the power supply decoupling capacitance (C3/C4) with the lower I/V resistor.

[hifinet]

So I'm new to the CamillaDSP and other signal processing part of moode, does it effect all playback? will the polarity inversion effect Airplay and Spotify also? I just want to make sure the polarity is correct, but honestly I'm not really sure if my system has anything else inverting.

Is there a good way to test this at the speakers?

Polarity inversion will affect all playback. Polarity inversion can also be done in MPD.

Most equipment does not invert polarity. If it does, it should be stated in the manual.

The only way to know is to display the input and output on an oscilloscope. Or the input could be mixed with the output in a mixer. If the output of a stage is inverting, the sum of the input and output will be zero (complete cancellation if the amplitudes are the same).

When the polarity is correct, the sound quality is better in comparison to inverted.