Topic: ADI-Pro ADC issue since the 177/87 update

Hi,

I use a lot my ADI-2 Pro units (the "first version") to make some needledrops of vinyl. And I use sometime very high sample rate for some very rare (and full analog) LP (384khz most of the time).

Since the last update (the 177/87), I have an issue with high sample rate files produced by the ADI-2 Pro unit. To reproduce it, I played a cassette (with my Revox B215 going through my analog preamp and going to the ADI-2 Pro through a dedicated Tape output)  and digitalize it at different sample rate as it was played (so this is not always the same segment for the different files, but this do not matter). This means that only the sample rate has been changed between the files, not the audio chains. Here the comparison of the left channels of the produced files in the spectrogram:

https://preview.ibb.co/c9XRoz/Comparaison_left_channel.jpg


As you can see, starting 358.2khz until 768khz, strange ripples starting around 20khz are present where all is fine for the file until 192khz. The most intriguing part is these ripples are only present on the left channel, everything is correct for the Right Channel no matter the sample rate.

Is this issue is specific to my unit? Is it possible to install the previous firmware as it is the last one who create the problem (I checked my previous files at 384khz produced before the installation of the last firmware  and they were perfect)?

Thanks in advance for your support!

2

Re: ADI-Pro ADC issue since the 177/87 update

You can flash back to any version. And in this case you have to do so as you just discovered a bug in FPGA version 177, which adds distortion on the analog recording signal's left channel at sample rates of 352.8 kHz and above. Thanks for finding and reporting this!

The former FUTs with version 174 / 86 are here:

https://archiv.rme-audio.de/download/fu … 174_86.zip

https://archiv.rme-audio.de/download/fu … 174_86.zip

An immediate update is not possible due to summer holidays, so it will take about two weeks until we can provide a fixed version of 177/87, which will have more changes that we finished working on already.

Regards
Matthias Carstens
RME

Re: ADI-Pro ADC issue since the 177/87 update

Thank you very much Matthias for this very quick answer. I was not expecting to have it so soon due to the holidays.

I will so install the previous version as you said.

Thank you very much again for your great support, I really appreciate!

4

Re: ADI-Pro ADC issue since the 177/87 update

Version 180 should fix this:

https://www.forum.rme-audio.de/viewtopic.php?id=27467

Regards
Matthias Carstens
RME