YAP: Yet Another Player

[hsmeets]

Hi All,

so some lifestyle changes resulted in listening a bit more through a pair of cans and to that I dusted off my (vintage?) AKG K-500 that I still like. The spare SB3 that I kept in a drawer doesn't have the oempf to drive these headphones properly. So something was needed and through fellow DIY'ers I was pointed towards to TI's TPA6120A2 headphone amplifier chip. I could have build a standalone amplifier that takes the signal from the SB3 but that would result in a less practical solution (2 boxes, cables, ...) to move around in the house. A single box solution is preferred and now that winter is upon us and we have long evenings it is perfect time for a DIY project (instead of being a coach potato). There are many other headphone amps designs out there but I liked the simplicity of using the TPA. Although 'simplicity': the TPA needs some thoughtful PCB design to prevent stability issues.

So far I got myself a Pi Zero 2W and a DAC from Hifiberry. To my surprise the headphone amp on that DAC board drives my AKG a bit better, but still need to crank up the volume quite a bit. So I guess I still am on for an amp with some more gain.

The player will not be outfitted with a screen or IR receiver (at least for now) but will get some buttons. Most of time I use a tablet/phone to control LMS. But it is good to have a few buttons like play/pauze/mute/volume. The internals should be a tidy as possible, I dislike multiple boards tied together with a cable loom. Parts, case, schematic, look and feel. It goes all hand in hand and influence each other so I made already some possible Cases, PCB layout concepts.

The case will likely be something like this (this one is about 25cm/10" wide) but will not be the final version.



Obviously working on a schematic too.



And gettig some idea about the pcb (although this is already out-dated....)



As you see I'll not stack the DAC on the Zero, I don't want the DAC to cover the antenna area, it probably will not be a real issue (I have it stacked at the moment too without issues) but I also want the whole PCB to have a low profile.

Software to be used: PiCorePlayer, SqueezeLite (duh), SqueezeButtonPi.

So far for now.

[hsmeets]

Seriously considering touch controls. Not a tft display but sensors behind a sheet of PMMA.

[hsmeets]

Some progress. 3 out of 5 schematics and PCB's.

Carrier board for RPI + DAC, with some GPIO's available on the righthand side connector (uController/Frontpanel)


PSU: 1 small SMPS for uController, 1 larger for RPI and DAC and 1 linear -12 and +12 for the head-amp.


Amplifier: 4 layer board, using the TPA6120 and an OPA2134 as input buffer (composite) to keep the DC offset from the TPA6120 in check.

[PaulH]

Some progress. 3 out of 5 schematics and PCB's.

Amplifier: 4 layer board, using the TPA6120 and an OPA2134 as input buffer (composite) to keep the DC offset from the TPA6120 in check.

Nice idea and nice 3D pictures.
What kind of program are you using ?

Where is it possible to manage HW switches to control functions ? I'm very interested!

Thanks

[hsmeets]

Nice idea and nice 3D pictures.
What kind of program are you using ?

Where is it possible to manage HW switches to control functions ? I'm very interested!

Thanks

Software for schematics and PCB design is KiCad (Version 6). It also does the rendering.

PCP/LMS control via HW switches connected to GPIO was tested succesfully using the SqueezePiButton extension.

Specifically I will use touchsensors using the AT42QT1010. For testing porpose I used the Adafruit touchsensor using the same chip.

Regards,

Huib