Exposing internal i2s signals

[Laniciffo]

Hi All,

After channel decoding AVRs'internal DSPs send i2s signals to multiple discrete DACs that eventually drive the power amplifiers and/or pre-outs.

Has anybody ever tried to extract these signals and feed them to external stand-alone DACs then to signal processors, additional amplifiers, etc... ?

 

[HarmonicTHD]

Hi All,

After channel decoding AVRs'internal DSPs send i2s signals to multiple discrete DACs that eventually drive the power amplifiers and/or pre-outs.

Has anybody ever tried to extract these signals and feed them to external stand-alone DACs then to signal processors, additional amplifiers, etc... ?

This is DIY hardcore and since you have to ask I would discourage you from it.

Alternatively if you get your AVR to first decode and then output multi channel LPCM you can run that via HDMI to a MiniDSP Flex HT.

 

[staticV3]

https://www.audiosciencereview.com/.../adding-post-dsp-spdif-outputs-to-avrs.19468/

https://youtu.be/zkOqmpGewx0

 

[Roland68]

Hi All,

After channel decoding AVRs'internal DSPs send i2s signals to multiple discrete DACs that eventually drive the power amplifiers and/or pre-outs.

Has anybody ever tried to extract these signals and feed them to external stand-alone DACs then to signal processors, additional amplifiers, etc... ?

If you have the technical know-how, it is no problem at all to extract the i2s signals, as long as they are accessible.
If you want to transmit the i2s signal over more than a few cm or externally, you should convert it to an LVDS signal and convert it back directly on the DAC board. You can find boards for this for a few $ on Aliexpress, among other places.
Almost every AVR has service manuals that you should use.
There are two things you should keep in mind. It could be that the AVR has control points somewhere on the signal path, e.g. for DC before or after the power amplifiers and you have to trick the AVR with fake or real signals to unlock it.
In many devices, the volume is controlled digitally, but is regulated on the analog side behind the DAC chips.

 

[Kal Rubinson]

Hi All,

After channel decoding AVRs'internal DSPs send i2s signals to multiple discrete DACs that eventually drive the power amplifiers and/or pre-outs.

Has anybody ever tried to extract these signals and feed them to external stand-alone DACs then to signal processors, additional amplifiers, etc... ?

I wrote a pair of articles for Audio Amateur about how to do this. TAA 3/95 and 1/97 from https://audioxpress.com/. I no longer have them in electronic form.
The key is knowing the pinouts of the relevant chips and that is hard to know if you do not have schematics.

 

[Laniciffo]

Thank you so much to all for your kind support !

I intend to try first on an old AVR to experiment all I can do with that.
My first objective is to get an analog constant line-level 'rec out' signal for whatever input I listen to. The AVR currently does not output anything when I use online audio services.

Second objective would be to record the digital decoded signal.
First just the stereo main channels and next the multi-channel complete set of an Atmos stream, but I guess that will be much more difficult due to synchronization issues. And I do not even know if I could find a multi-channel digital recorder.

 

[restorer-john]

Ask dweeblabs here on ASR. @Weeb Labs