I wanted to share my findings on the Squeezelie-ESP32 in combination with other amplifier.
First of all: Many thanks to the developer of the Squeezelite-ESP32. It's a great project. I'm also interested in the hardware, but it's not so simple available. So I was interested in other solutions.
I used one of these WONDOM devices (starting with 30$):
http://store.sure-electronics.com/product/AA-AB32255 or
http://store.sure-electronics.com/product/AA-AB32256. Both are very similar. They are using the same (or similar in the case for the TAS5756) chip as used in the SqueezeESP hardware. They both offer to use the i2s input.
The board is larger and has a better cooling, so it can provide 2x30W. The PCB has twice the thickness of a typical PCB. It seems quite well designed. And it was availabile within 2 days from a distrubutor in Germany for 30. Therefore I was interested if these boards would work with the Squeezlie-ESP32 firmware.
First nothing was working. Even the TAS chip was not detectable. So I tested the setup first as a simple i2s DAC.
Some findings:
- It seemed for me that I could the setup get working when connecting 3.3v supply to the 3.3v pin of the i2s connector of the amplifier board only. This pin seems not to be connected to the internal 3.3v of the amplifier. But it seems to have some function regarding the input of the amplifier. Maybe I'm wrong. I could not find how it's working. As far as I could find that it is electrically connected to a capacitor, which other pin is connected to ground. These findings could also be a source of a non working bluetooth in combination with my phone. So one can try without, in case of problems provide 3.3v from the esp on that pin, then it should work.
- The boards have a connector for a rotary encoder for controlling the amplification. If no encoder is connected, amplification will be maximum. The encoder is connected to a mikrocontroller from HOLTEK. This mikrocontroller is connected via i2c to the TAS575x. Therefore it is not possible to use this board with a TAS575x setup in Squeezelite-ESP without modifications.
- The pins 3 and 6 of the HOLTEK mikrocontroller are connected to the i2c pins of the TAS575x. The HOLTEC has a larger pin spacing and larger pads. It is possible to desolder these two pins and connect them to i2c pins of the ESP32. With that modification its possible to configure the amplification chip in the Squeezelie-ESP32 firmware as a TAS575x
- The amplification board has a standby input. If it's pulled to ground, amplifier is in standby. This input can directly connected to a ESP32 pin and be used in Squeezelite-ESP32
I used a wrover ESP32 and connected the needed pins directly. One needs a DC-DC converter to provide 3.3v to the ESP32. The 3.3V regulator of the amplifier board has not enough power to drive the ESP. I used power supply from the output of the input diode of the amplifier board. Then one can use the inverse voltage protection of the amplifier board (an example of the quite well design of the board. It even provides two power inputs (power (as screw terminal or connector) and battery (pins)). Power and battery is even separated by a diode.
Of cause this is not the nicest setup, but it needs 3 just components: amplifier (30$) , ESP WROVER (7$) and a DC-DC converter (1$). (And of cause a power-supply)
In combination with a pair of D310 from Wharfedale I got a very nice setup for my homeoffice. Nice clear sound and enough power even with with a 36W (15V 2.4A) power supply (had a spare one in my shelf).
Maybe someone finds this helpful.
Florian