ProtoDAC TDA1387 X8 project

[michaelagiles]

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.

If you connect 5vdc  to J3 AND jumper J4 1-2,   3-4 this will power both the MA and the  Rpi with both 5v and 3.3v.  I am not sure what happens if you un-jumper J4 except I am certain you will need a 3.3v supply connected to J5 to power the MA.  I THINK the J3 5v will still power the Rpi but this needs to be better investigated. Don't take my word for it!

I have had another issue arise that maybe someone can help with. I have setup SOX resampling to selectively resample to 384 but adhere to the base frequency.  This works for 44.1, resampling to 352 but on 48 base data it still indicates 352 rather than the correct 384 when I check Audio Info. Is this what is actually happening or is it a reporting error?
Can it be corrected?
Pi 4b, FifopiMA, ProtoDAC, Pass B1 , Pass SLOB active Xover, Luxman and Ayima, OB Markaudio and Dayton Audio.

BTW I found a very noticeable deterioration with the 3.3 v supply to the ProtoDAC before I realized what was happening.
MG