Volume control for sbc/ i2s DAC

Hi all,

I want build an amp feeded by the arylic board connected to an i2s dac. So the chain will be:

Arylic -> Kali recloker -> I2s Dac -> power amp

I want use Arduino to control the volume by a rotary encoder and from a remote. But I want to be able as well to control it from the Arylic software on the phone.

The dac board (AUDIOPHONICS DAC I-Sabre ES9038Q2M KALI EDITION Raspberry Pi / I2S & SPDIF / PCM DSD - Audiophonics) permit the i2c connection to control volume.

The question is, if I change the volume directly on the Dac, the Arylic board change the volume as well, or the 2 volume are independent? (Dac is set as slave)

Thank you
 
ES9038Q2M only has one set of volume registers, and only one I2C bus address. Setting up all the dac registers, including volume, involves RPi talking over I2C bus to the dac chip (maybe with Kali and a local dac MCU involved too). Since I2C bus is tied up for that connection, probably best to put an analog volume pot at the output of dac line output if you can. Otherwise, probably best to stick with the RPi volume control.
 
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Hi, thank you for your answer but I don’t understand.

I connect the Arylic board (not rpi) with i2s pin. I will use i2c pin only for control the volume with Arduino.

The 2 volume (on the arylic board and on the dac) are independent or if I change one, the other one change as well?
 
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Not sure what you mean by the Arylic board. There is a digital volume inside the ES9038Q2M dac registers, but there is only one I2C address that is used for access any and all dac I2C registers. Only one I2C bus master can control the I2C bus in normal conditions, that one device probably must be the RPi or the dac's MCU which then talks to the RPi.

That means there is no other I2C address available that Arduino could, as I2C master, use to talk to ES9038Q2M registers and thereby control dac volume.

Also, it is best to either use ES9038Q2M volume registers, or to use an analog pot. Those are usually the two best methods. ESS explains why in their document at: http://www.esstech.com/files/3014/4095/4308/digital-vs-analog-volume-control.pdf