Reply from Metrum Acoustics / Sonnet
Dear Audio enthousiast,
The new Metrum and Sonnet I2S-HDMI modules are out! We encourage that audiophiles are searching for the best sound and correct configuration with their favorite streamer product(s). We made a table that is available in the Attachments section of the I2S-HDMI module product page, direct link here: https://metrumacoustics.com/index.php?controller=attachment&id_attachment=29. We gathered pinouts where we could find them and published them, as to ease the puzzling amount of data. We can share with you that the large mayority of manufacturers have the same polarity for BCLK and MCLK (as shown in the table). LRCLK and SDATA can have a different polarity over manufacturers. What that implies is that you, as a user, can switch the polarity of the digital signals for the LRCLK and SDATA signals. In the real world, this gives you the possibility to swap the Left and Right channel with the LRCLK jumpers (LRCLK = Left Right Clock: switch 1A to 1B, and 2B to 2A to swap channels), should they be assigned wrongly. For SDATA (Serial Data) you can do the same, which has the same effect as changing the signal polarity of the speakers, only in this case you change the phase of the analog output of your DAC. If jumpers 3 and 4 are placed in the ‘wrong’ position, you will still have musical output, albeit in the wrong phase. Detecting the phase of your setup is a little more difficult than choosing your favorite recording and checking left and right, which is why we gave the world a table to work with. What could help you is play Ouverture 1812, skip to the bombastic cannon part and check whether the speaker cones move inwards or outwards (you have to be fast though!)
The Antipodes signal pinout is displayed on I2S Connection on Antipodes - Master Thread - #25 by MarkCole (Nov 21, 2022 9:48 PM).
To respond to compatibility with PSaudio standard (our Type 1 jumper placement), and Metrum stating Type 3 jumper placement: to make Antipodes correspond to PSaudio standard, LRCLK and SDATA need to be changed (I2S Connection on Antipodes - Master Thread - #9 by MarkCole). This is exactly the difference between Type 1 and Type 3, and should disambiguate, and/or clear up what the jumpers do and why Metrum/Sonnet advises to go with the Type 3 setting when playing with Antipodes streaming products.
More info on I2S and what it does: Metrum Newsletter - January 2024 - Metrum Acoustics
Happy listening!
Roelof,
Team Metrum