ProtoDAC TDA1387 X8 project

[Tim Curtis]

I have simpler setup with RPi, Allo Kali and ProtoDAC. Usually silent at start and end of tracks. Rarely a tic at the end of a track. I'm not sure what is causing it with your setup.

I have the same at the song starts, never after. It's very soft, not obnoxious, and subsequent songs in the same album, even if I jump to them are quiet, beginning to end. In my case it may come from changing input resolutions. I use SoX, and my moode setting honors the resolution 'family' (44.1 khz or 48 khz) when upsampling to 4fs. always pops on the first song of a session.

Whats your hardware stack?

[Skip Pack]

Rpi4B, 4GB, Allo Nirvana PS, Protodac 1387 x8 hat. 2 usb3 1TB SSDs.

[hlucas]

Hi folks,

Here is my second ProtoDAC built from Hifinet's kit with a case that matches my diy headphone amp. I also added a 10$ hat with a bunch of capacitors that claim;

"On-board capacity of 5526uF, the sound becomes sweeter and more transparent, suitable for various expansion boards..."

I don't know what sweet sound means, but it improves detail when I use its power input instead of RP usb-c. But it also increases the first pop at Protodac startup cycle. I am not convinced enough will keep it for some time and test again... 

Has anybody used similar solutions? Or any comments.

Also, thank you very much, @hifinet . Your email support was exceptional.

[Ludomaniac]

One thing I noticed about this kit that when you start to play a song it produces a 'click' noise in the speakers (not a big deal) - but is it possible to dampen that sound a bit with some more components or some other clever solution?

I have the same hardware stack as @hifinet and similarly only a vary rare audio start tic. I also get these rare anomalies on other audio devices which would suggest that it's not necessarily unique to ProtoDAC.

Try removing the Q7 and connecting the ProtoDAC directly to the Pi.

Will try and get back to you - thanks for the tip!

[marco.mosca]

I received this question regarding polarity inversion:

"I have a question regarding polarity inversion. The document says that we have to invert the polarity in Moode. Does this mean I can't use Raspberry Pi software that doesn't allow this inversion?"

You can use software without a polarity inversion option. Simply reversing the +/- speaker leads will reverse polarity. Most components such as preamps and power amps do not reverse polarity, but some do. Check your manuals.

Would it be the same if +/- is reversed at the output of the PCB?

Thanks.
Marco

[hifinet]

I received this question regarding polarity inversion:

"I have a question regarding polarity inversion. The document says that we have to invert the polarity in Moode. Does this mean I can't use Raspberry Pi software that doesn't allow this inversion?"

You can use software without a polarity inversion option. Simply reversing the +/- speaker leads will reverse polarity. Most components such as preamps and power amps do not reverse polarity, but some do. Check your manuals.

Would it be the same if +/- is reversed at the output of the PCB?

Thanks.
Marco

It's a single ended output with signal (+) and ground (-). If you reverse at the output of the PCB, you would then be grounding the signal (connecting + to ground), and creating signal from ground ( - to signal), which has no signal.

[marco.mosca]

I received this question regarding polarity inversion:

"I have a question regarding polarity inversion. The document says that we have to invert the polarity in Moode. Does this mean I can't use Raspberry Pi software that doesn't allow this inversion?"

You can use software without a polarity inversion option. Simply reversing the +/- speaker leads will reverse polarity. Most components such as preamps and power amps do not reverse polarity, but some do. Check your manuals.

Would it be the same if +/- is reversed at the output of the PCB?

Thanks.
Marco

It's a single ended output with signal (+) and ground (-). If you reverse at the output of the PCB, you would then be grounding the signal (connecting + to ground), and creating signal from ground ( - to signal), which has no signal.

Sorry for the additional question. Thus, inverting the polarity of the signal cable connecting the ProtoDAC to the preamp won't work. Correct?

M

[hifinet]

Yes, correct. The easiest way is to reverse speaker leads on both speakers.

[jonners]

How many listeners can reliably identify reversed polarity? Not many I suspect. I can't hear it so I don't worry about it.

[Skip Pack]

It's a very interesting subject, relative polarity  in audio. I heard it clearly back in my teens on a bottom scraping college dorm system, and then to varying degrees over the intervening years. I have always listened to both polarities when setting up a system just after getting the side-to-side polarity set. It always varies from recording to recording depending on the complexity of the mix and the care taken capturing tracks. I also was startled to hear how distinct it is on my latest system that uses fullrange (almost) drivers. I think the configuration of crossovers affects the audibility. Having no crossovers is the single point of commonality with that pretty retched system of my college dorm mates. I also noticed that the ProtoDac with no onboard upsampling and the simplest possible I/V conversion increased the discernability of polarity.

Skip