• Registered: 2023-12-16
  • Posts: 2

Topic: A strange signal appears on the analog input - ADI 2 PRO FS R BE

Hello!

I usually send a DSD signal to the PRO FS R. (From HQPLAYER/ROON or Audirvana Studio) A strange signal appears on the analog input when the conversion type of the line input is set to DSD. It doesn't matter whether the Direct DSD mode is on or not. It's strange that it doesn't appear on the "summary" screen. If I switch the line input conversion to PCM, that signal appears on the summary screen. hmm

There is currently nothing connected to the analog inputs!
A Jack/RCA converter is connected to the line outputs, which goes to an amplifier, and the signal also goes to a headphone amplifier via an XLR cable.

When sending a PCM signal, e.g. from the Amazon Music application, there is no strange signal on the analog input. Mac OS: Sonoma 14.1.2 (23B92).

I made a video, so maybe it will be more understandable. Could this be a bug in the firmware?

https://youtu.be/ObMLBKzQA2A?si=72QOu9-whXObOgPL

I updated to the latest firmware version yesterday.

Thanks for your help! smile

2 Reply by KaiS (edited by KaiS 2023-12-16 23:05:11)

  • KaiS
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  • Registered: 2020-02-05
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Re: A strange signal appears on the analog input - ADI 2 PRO FS R BE

item1979 wrote:

…There is currently nothing connected to the analog inputs!…

That’s exactly the point.

Without termination and screening, the open input catches crosstalk from the high frequency DSD signal, or anything else.

Without anything connected it finally doesn’t matter.

KaiS's Website

3 Reply by MC

  • MC
  • MC
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  • Registered: 2007-04-06
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Re: A strange signal appears on the analog input - ADI 2 PRO FS R BE

KaiS wrote:

Without termination and screening, the open input catches crosstalk from the high frequency DSD signal, or anything else.

There is no crosstalk whatsoever, and shorting the inputs does not change the effect.

The reason is a different one: In PCM mode the vertical input level meters show audio up to 40 kHz. High-frequency noise is not much visible on the meter. In DSD mode the DSP converts DSD audio data to PCM level meter data, to be able to show the audio level. The bandwidth here is 80 kHz. The higher bandwidth causes a higher level (of inaudible noise) shown on the meter.

For the OP: don't forget that the numbers shown are peak. RMS would be much lower.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2023-12-16
  • Posts: 2

Re: A strange signal appears on the analog input - ADI 2 PRO FS R BE

MC wrote:
KaiS wrote:

Without termination and screening, the open input catches crosstalk from the high frequency DSD signal, or anything else.

There is no crosstalk whatsoever, and shorting the inputs does not change the effect.

The reason is a different one: In PCM mode the vertical input level meters show audio up to 40 kHz. High-frequency noise is not much visible on the meter. In DSD mode the DSP converts DSD audio data to PCM level meter data, to be able to show the audio level. The bandwidth here is 80 kHz. The higher bandwidth causes a higher level (of inaudible noise) shown on the meter.

For the OP: don't forget that the numbers shown are peak. RMS would be much lower.

Thank you very much for the quick and detailed answer! smile