ProtoDAC TDA1387 X8 project

[OnkelPH]

Started with listening, just protodac on top of rpi. First impression is very good, large stereo image. It will need a few hours before things fall into place. Only cons is some background noise. Possebly from the rpi? Next step is linear powersupply and shealding, than reclock.

[hifinet]

Which RPi are you using? In my experience, Zero W (single core) has much less noise than RPi2 < RPi3. Noise is mostly conducted and not radiated (so skip the shield), and is generated by the RPi and not the power supply.

[OnkelPH]

Which RPi are you using? In my experience, Zero W (single core) has much less noise than RPi2  < RPi3. Noise is mostly conducted and not radiated (so skip the shield), and is generated by the RPi and not the power supply.

RPi 4+

[OnkelPH]

An update after listening over the weekend. Background noise: I'm not worried. reduced it somewhat with adjustments in the signal chain. Playing the DAC into my Dynaudio activ speakers, just had to turn down the volume on the speakers and almost all the noise disappeared?. Now I’m playing with panasonic FM and FR-A and Mundorf MCap EVO Oil 6,8 uf. The first that comes to my mind is; tubesound. Worm and big soundstage. I’m so happy and excited.

[hifinet]

An update after listening over the weekend. Background noise: I'm not worried. reduced it somewhat with adjustments in the signal chain. Playing the DAC into my Dynaudio activ speakers, just had to turn down the volume on the speakers and almost all the noise disappeared?. Now I’m playing with panasonic FM and FR-A and Mundorf MCap EVO Oil 6,8 uf. The first that comes to my mind is; tubesound. Worm and big soundstage. I’m so happy and excited.

Thanks for the update. 

An isolator/reclocker will definitely improve the sound.

The Mundorf Mcap EVO Oil is rated 8.5 in Humble Homemade and reasonably priced. Diameter is a little large. Smaller in the 4.7uF value. Sounds like a great choice.

[OnkelPH]

An update after listening over the weekend. Background noise: I'm not worried. reduced it somewhat with adjustments in the signal chain. Playing the DAC into my Dynaudio activ speakers, just had to turn down the volume on the speakers and almost all the noise disappeared?. Now I’m playing with panasonic FM and FR-A and Mundorf MCap EVO Oil 6,8 uf. The first that comes to my mind is; tubesound. Worm and big soundstage. I’m so happy and excited.

Thanks for the update. 

An isolator/reclocker will definitely improve the sound.

The Mundorf Mcap EVO Oil is rated 8.5 in Humble Homemade and reasonably priced. Diameter is a little large. Smaller in the 4.7uF value. Sounds like a great choice.

Any recommendations? I’v looked at Ian Canadas Fifopima or Q7

[Tim Curtis]

I would have said the Allo Kali Reclocker but they are out of production and not available anywhere. Thats what I'm currently using but it's only a matter of luck that I had a couple from years past.

if I were in the market today I'd prolly go for the IanCanada Q7.

[hifinet]

I think the Q7 is the only isolator/reclocker HAT available. The FifopiMA the only reclocker.

Other than that, if you have a master DAC HAT (with GPIO and two clock crystals like the old HiFiBerry DAC+ Pro) just collecting dust, you could try that. The master DAC will reclock the I2S of the GPIO.

[michaelagiles]

10 years! It is a good time to donate again!

A couple of items:
I recently added a FifiPiMa re-clocker and I am so far pleased with the results. There were a few stumbling blocks though. Hopefully my errors will help anyone attempting the same.

Firstly, the GPIO on the FifoPiMA provides only 3.3vdc to the power pins of the Protodac. I use a Salas DIYAudio linear supply and am feeding the FifiPI through the RPi so far. I needed to disconnect the pwr supply pins to the ProtoDac using the header with pins 2&4 removed as suggested by someone earlier in this thread and feed directly yo yhe through holes provided on the dac board. These were jumpered to the terminal strip on the MA. This worked fine!

Second - I tried to feed the MA and RPi through this terminal strip but it would not boot properly if I connected everything and then started the power supply. Apparently the startup routine of the MA is quicker than the pwr supply startup and it gets confused. So I had to add a switch in the supply line so that the power supply could be up and running before switching everything on. It worked!

Thirdly: I had first to remove 2 bypass caps on the bottom of the Protodac board (0.1uf , Vishay MKP) to fit physically before adding the extra header. I was interested to perceive that there was a difference after they were re-installed. Just a little "sweeter" - whatever that means!

Lastly there has been some discussion on this thread and seemingly forever elsewhere about the effect of absolute polarity. I have always found that switching polarity made a difference , but that difference was very much recording dependent. From some experience in recording control rooms, admittedly some years ago, polarity between mic feeds was always a consideration, but absolute polarity was never mentioned. And how would this be determined in a multi track, isolation booth type environment? A minimalist/natural recording can take this into account but I don't know that it actually is done.

It seems to me preference in this is often a matter of taste/personal preference/system characteristics.
I often wonder if what I/we hear is just a non-linearity in our systems that we tailor to our own preferences? As nelson Pass has demonstrated, positive going 2nd harmonics added to a signal increase spaciality and warmth while negative going does the opposite.

In any event, be sure to Enjoy the Music!
MG

[hifinet]

Thank you for posting this.

The MA and Q7 manuals state "or other audio HAT on top of FifoPiMA." Do all other audio HATs use only 3.3VDC?

The TDA1387 will operate from supplies of 3.0 to 5VDC, but the typical current output at 3.0 VDC is only 0.6mA compared to 1mA at 5VDC (per chip), resulting in lower output voltage after I/V.

Do you know if the 5VDC from MA J3 is isolated from the Raspberry Pi? I think this also applies to Q7. It states that the 5VDC comes from the Q7 GPIO.