Tuesday, November 15, 2016

Rpi with Supstronics x400 HAT

In this blog posting i am concentrating on combining the Raspberry Pi 2 or 3 with the Suptronics x400 which I picked up for less than $26 including shipping. This has gone up in price and took over a month to arrive. I picked this particular digital audio converter (DAC) because it connects directly to the RPi3 GIPO pins. An external DAC can increase the quality of music out of Raspberry Pi computers because they have better audio components than the low cost Pi components.  The x400 has three different outputs, RCA jacks that can be connected to an amplifier, headphone jack that uses an amplifier circuit and speaker connections for up to 20 watts of amplification per channel. I like that jumpers can be used to turn off sections of the x400 that aren't needed. I also like that it has onboard hardware volume control, even though I typically use the software volume control on the Moode Audio software. The jacks are not of high quality and are attached to the board in a flimsy fashion. This can be modified for anyone wanting a better connection.
Two GPIO pin extender shown, note gap.
Rpi2 with x400 HAT amplified for cube speakers.
x400 Hat on Rpi2 with USB FLAC files, note wires too big for lugs.
Above Rpi2 with x400 HAT running Polk Audio speakers
Moode Audio sets up the x400 Hat quite nicely. Just select the x400 DAC from the list of I2S audio devices, reboot then apply the MPD again. I set the system settings off an ethernet connection including the wifi settings, then reboot and removed the ethernet cable. Then the Moode Audio interactive software should be available on your web browser at the local wifi address and will play the selected music through the x400. You can use the RCA audio output jacks, the headphone jack or connect speakers to the wire lugs. Again, the audio connections on the x400 are a little flimsy so be careful not to break anything off.  

One reason I chose to experiment with Moode Audio is because it has a customization section which includes filter options for the Burr Brown PCM5122 chipset. The x400 includes this PCM5122 chip so you can on the fly change between different digital interpolation filter settings. Some fun discussions on the internet on these different filters (see links below). My old ears can’t tell the diff, but yours might.

Originally I installed the x400 on a Rpi3, then looked at my inventory of Rpi boards and thought it would be better on the Rpi2 with a $3.50 usb wifi dongle. Used an old laptop power cord who’s socket fit the x400 power input. For under $70 US (plus microsd and power supply) we have a system that is portable, low energy consumption, plays and amplifies music quite nicely with an interface off any web browser.  

Update to Rpi3 and Rpi2 discussion now includes using the $5 Rpi Zero. Soldered GPIO pins to the Zero and screwed it to the Suptronics x400 and after two attempts at soldering it worked! 
DAC HAT attached to Rpi Zero.
Wifi adapter and 32 gb sd card on USB, amplifier for two speakers.
Bottom view.
Side View.
Currently running RCA plugs through Carver to power some Paradigm speakers. FLACs sound excellent.

Three variations of Rpi's and DAC HAT.
These systems have been working very nicely with the latest version of Moode Audio software, amplifying the sound to various speaker configurations.

There are some new HATs from Suptronics which promise to provide affordable sound from Rpi integration. New boards and kits can be found at this web address: http://www.suptronics.com/ My own work is focusing on the x5000 series for solar powered music solutions. Stay tuned to this and other blog entries listed below for any updates. 15 second video of solar powered Suptronics HAT system: https://goo.gl/photos/w775JvDVJfxWM1YSA

Further reading:
Search on either Supstronics or Suptronics, it is out there under both names.

There are some foreign language websites that can be translated by google translate which have some interesting content too. Here are some links to other x400 content:

X400 DAC filters:

The evaluation has been broken out into the following audio sections:

And a related post, Uniqueness of the Rpi.

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