ProtoDAC TDA1387 X8 project

[hifinet]

Thanks for the info. Plan to look into this problem in more detail. The worst pop always seems to be on the first track after being off for some time. I have some caps in the 3.3uF to 10uF range that don't seem to pop, both polypropylene and polycarbonate. Will try to determine if there is a common design. Also, if a cap has a popping problem, can it always be fixed by bypassing with a lower value cap .

I also need to work out a better test procedure. Currently I have been hot swapping caps, so this may miss a popping problem.

Has sound quality improved with the addition of the Miflex?

[hlucas]

I think so. Bass guitars now have more character, and cymbals sound smoother. However, the Miflex caps are pretty big and expensive. I'm fortunate to use the DAC with a tube amp, which allows me to use smaller value caps (0.22uF). If anyone wants to try, 0.33uF would be better for the lowest frequencies. I bought 0.22 ones used.

They also allowed me to use 1x Panasonic + 1x AudioNote Kaisei decoupling caps instead of 2x Panas. Kaisei has more detail, but the sound was harsh with old Sprague caps. It is still detailed but easier to listen to with MiFlex caps.

[hifinet]

Miflex seem to be consistently rated very high. Usually used as bypass caps due to large size and high cost. The interesting ones are the KPFM copper foil and PP. Smaller and less expensive. Quoted dissipation factor is still very low at less than 0.005 (compared to 0.0035 for the p aper/oil; all very good numbers). I think a lot of the performance advantage is due to winding technique. 

I wonder if a film bypass cap on the Kaisei would smooth it out .

[wolf7250]

Here are cases that I use when there are several HAT'S on top of the Pi.

Older "dog bone" case. Not sure if this is still available.


Newer case meant for stacked Pi's. Still available AFAIK.

Hi do you have a link where to buy the case for stacked pi?

The Geekworm is the one that I personally use. Available on Amazon and other sites. The brown color is a removeable paper protective layer to keep the acrylic from being scratched in the package.  It also comes with a bunch of standoffs.

@hifinet do you use this case with your RPi Zero W?
I'm looking at getting a Zero 2W and wondering if it would work?

If so, did you need to make some modifications to it? I.e. drill some new holes to account for the reduced width of the Zero boards compared to the 3A/3B/4B etc?

[hifinet]

Here are cases that I use when there are several HAT'S on top of the Pi.

Older "dog bone" case. Not sure if this is still available.


Newer case meant for stacked Pi's. Still available AFAIK.

Hi do you have a link where to buy the case for stacked pi?

The Geekworm is the one that I personally use. Available on Amazon and other sites. The brown color is a removeable paper protective layer to keep the acrylic from being scratched in the package.  It also comes with a bunch of standoffs.

@hifinet do you use this case with your RPi Zero W?
I'm looking at getting a Zero 2W and wondering if it would work?

If so, did you need to make some modifications to it? I.e. drill some new holes to account for the reduced width of the Zero boards compared to the 3A/3B/4B etc?

With 2W, I just leave the non GPIO side hanging. There is really no need to support it.Access to the micro USBs is very difficult when it is in the case. The power cable and OTG USB need to be installed before assembly of the case.

After Tim's rec, I have been recently using 3A+ instead of 2W. It already has a USB A port (and GPIO header), and it is  on the front side opposite the RCA jacks of ProtoDAC. Easier access. No need to get an OTG cable.

[gperpetuo]

Hi,

When soldering the TDA1387 X8 Module to the pcb, I did not notice I was soldering "mirrored". In other words, I soldered only 2 pins on the side I should have soldered 6 and soldered 6 pins on the side it was enought only 2 (25, left channel and 28, 5V).

With this, I gave 5v to the board and no GND.

Question:
With this, could I damage anything on the board? (the module was on correct position, only the pins were not connected)

I ask this because now I have a short somewhere on the board and I didn't have it prior to soldering the remaining pins, so the short is somewhere in the TDA1387 module...

Thanks,
Gonçalo Perpétuo

[hifinet]

This should not have caused any damage. Double check the polarity of the C3 and C4 electrolytic caps. What is the behavior that leads you to believe there is a short?

[wolf7250]

Here are cases that I use when there are several HAT'S on top of the Pi.

Older "dog bone" case. Not sure if this is still available.


Newer case meant for stacked Pi's. Still available AFAIK.

Hi do you have a link where to buy the case for stacked pi?

The Geekworm is the one that I personally use. Available on Amazon and other sites. The brown color is a removeable paper protective layer to keep the acrylic from being scratched in the package.  It also comes with a bunch of standoffs.

@hifinet do you use this case with your RPi Zero W?
I'm looking at getting a Zero 2W and wondering if it would work?

If so, did you need to make some modifications to it? I.e. drill some new holes to account for the reduced width of the Zero boards compared to the 3A/3B/4B etc?

With 2W, I just leave the non GPIO side hanging. There is really no need to support it.Access to the micro USBs is very difficult when it is in the case. The power cable and OTG USB need to be installed before assembly of the case.

After Tim's rec, I have been recently using 3A+ instead of 2W. It already has a USB A port (and GPIO header), and it is  on the front side opposite the RCA jacks of ProtoDAC. Easier access. No need to get an OTG cable.

Thanks very much! Really appreciate your recommendation 

[hifinet]

The other thing to mention is that the case extends to cover the Ethernet and USB ports of an RPi 3B.  The 3A+ is limited to the mounting holes, so the case overhangs on the USB port end.

[gperpetuo]

I tested continuity between 5v and GND and it was positive (beep from multimeter)

Edit:
I managed to remove the x8 module. No continuity on the pcb now between vcc and gnd.

Checking the module, I have continuity between vcc and ground.

Checking the capacitors on the underside, I have continuity on half of them