TOPIC: NanoAVR HDA Noise Floor

Hello zmaile,

thanks for your helpful reply!
We have in fact very good equipment at work (I am an analog electronics engineer), including spectrum analyzers and 4GHz MSOs, but none of them is audio-related, so "my" Keysight MSOS 404A does decode the I2C, UART and SPI but not the I2S protocol. So there is some effort to prove the HDA's behaviour at work, for example an appropriate hdmi source is missing.

On the other hand I am very interested to find the real source of these disturbances. The I2S protocol seems to be straight so it should be easy to observe as you stated.

The USB protocol includes 1ms frames or 125us microframes (full speed), so this could be a source. Otherwise the HDA should't generate these frames as it does not act as a master and the host (PC) was connected via LAN, not via USB.

Cheers, Timo

Hello,

here are some additional nanoAVR HDA measurements regarding the noise floor:
link to the measurements



It would be nice to read a comment from devteam.
- Is there a possibility to change the filter from fast to slow rolloff? Would this be helpful for lower noise?
- Do you know any other possible changes in the future to get lower noise?

The nanoAVR HDA is a very nice solution for my requirements of course, at least the DSP-part including the filters. Thank you for that development!

Cheers,
Timo

Hello,
because of requests for pictures I put some insights of the nanoAVR HDA here:
https://ibtk.de/project/amplifier/nanoAVR_HDA/Fotos/20180411_MiniDSP_nanoAVR_HDA_fotos.html
The device uses the miniDAC8 board, which is available on the miniDSPs website too. So it should be possible to replace it with a DAC/balanced output amplifier board with better SNR data in principle.
There exist some ideas, LTSpice simulation files and Eagle files using the ES9038pro and OPA1612 already but it's still a lot of work.
Is there anybody out there, interested in the realization of an alternative DAC board together with me (would need some experiences in low noise analog design and especially µC design and programming)?
Cheers, Timo