Hello everyone,
I am currently running a Raspberry Pi with a Stereo Audiophonics ES 9038 DAC. The power comes from an Audiophonics power supply and is routed to the Raspberry via an Audiophonics power management module. This makes it possible to safely switch on and shut down the Raspberry like an ATX switch on a PC. The music is output to the speakers via a Marantz SR 8015 (dual mono). Now I would like to build a new device and have ordered the parts described in the picture. The power management module controls the raspberry via the GPIO pins 04, 17 and 22. Is it possible to do this when the raspberry is installed on the station Pi, e.g. via the GPIO bar J2 of the FifoPI.
Thanks in advance for your help.
Greetings from Bonn, Germany
I am currently running a Raspberry Pi with a Stereo Audiophonics ES 9038 DAC. The power comes from an Audiophonics power supply and is routed to the Raspberry via an Audiophonics power management module. This makes it possible to safely switch on and shut down the Raspberry like an ATX switch on a PC. The music is output to the speakers via a Marantz SR 8015 (dual mono). Now I would like to build a new device and have ordered the parts described in the picture. The power management module controls the raspberry via the GPIO pins 04, 17 and 22. Is it possible to do this when the raspberry is installed on the station Pi, e.g. via the GPIO bar J2 of the FifoPI.
Thanks in advance for your help.
Greetings from Bonn, Germany
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Often Ian's dac controller is plugged into the un-isolated GPIO bus connector on FIFO_Pi. Are you going to use his controller or your own?
My understanding is that if the software (Volumio for me) provides a driver for the DAC chip, the controller is not yet required.
Does Volumio support putting the dual DAC chips into fully synchronous mode? If not, you probably want Ian's controller as SQ is clearly best for that chip in synchronous mode. My guess would be that Volumio doesn't do that since its hard to get that mode to work without a FIFO buffer or fully synchronous (as far as the dac is concerned) asynchronous USB (asynchronous relative to the RPi clock, that is). IIRC, synchronous mode has also been done over GPIO bus if the dac chip is made the I2S clock master. Also IIRC there are some existing RPi drivers that support that mode with a single ES9038Q2M. Don't know about dual mono though. Also don't think FIFO_Pi supports the dac chip as I2S clock master.
That said, you might be able to script I2C bus comms from RPi to the dac chip control registers and put it into synchronous mode yourself.
EDIT: Also wondering what output stage you are planning to use?
That said, you might be able to script I2C bus comms from RPi to the dac chip control registers and put it into synchronous mode yourself.
EDIT: Also wondering what output stage you are planning to use?
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The transformer output stage approach is not ideal from a distortion perspective. However, it may sound better than Ian's opamp output stage. The reason transformers are less than ideal is because the dac chips are designed to produce the lowest distortion into an offset virtual ground (with ideally zero input impedance). The transformers appear as a somewhat higher impedance load for the dac chip, thus distortion increases.