1 Topic by dr.larkos (edited by dr.larkos 2024-01-19 06:13:30)

  • Registered: 2017-05-04
  • Posts: 58

Topic: Error message "DC Detected Line Deactivated"

Greetings gentlemen.

My RME ADI-2-Pro FS R BE is showing a permanent error message "DC detected line deactivated. Check source/remove erroneous signal to recover." The error message stays there no matter what control you try to activate (except rotating the large volume control but the error message pops up again, immediately, once you stop rotating that control).

This is despite that no equipment whatsoever is connected to it and the unit ended up being connected directly to the wall outlet, bypassing a set of line conditioners (that are normally in use). The error message first showed up earlier today as I was configuring the unit to switch from Analog to USB source. The error message stayed there, as a permanent fixture, while I started to remove, one at a time, every single piece of peripheral equipment--powering the unit on and off, at each step, until there was nothing connected to it, just the unit connected directly to the wall power outlet!! Looking forward to your thoughts.

Thank you in advance..................... dr.Larkos

2 Reply by KaiS (edited by KaiS 2024-01-19 06:41:33)

  • KaiS
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Re: Error message "DC Detected Line Deactivated"

Not very likely a remedy, still worth to try a reset:


While powering up, push and hold the VOL button (NOT the VOLUME dial) and Encoder 1, until you see the message: “Reset done“.

User Setups and EQ Presets are not deleted.


Or a full factory reset:

While powering up, push and hold the VOL button (NOT the VOLUME dial) and Encoder 1 and Encoder 2, until you see the message: “Reset done“.

All user Setups and EQ Presets are deleted.
Take notes before, or store them through the Remote App, if you want to keep some.


If this doesn‘t help:

There‘s something broken inside ADI-2.
Get it serviced.

KaiS's Website

  • Registered: 2017-05-04
  • Posts: 58

Re: Error message "DC Detected Line Deactivated"

Thank you, Kais. It worked.

dr.larkos

4 Reply by MC

  • MC
  • MC
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Re: Error message "DC Detected Line Deactivated"

Is that unit on the latest firmware?

Regards
Matthias Carstens
RME

MC's Website

5 Reply by dr.larkos (edited by dr.larkos 2024-01-23 06:55:38)

  • Registered: 2017-05-04
  • Posts: 58

Re: Error message "DC Detected Line Deactivated"

Yes, Matthias, the latest one (122) was in use when DC protection was triggered. I surmise the problem was triggered by the interaction of "ultra-high" frequency noise ("phantom" signal) present in the RMR's analog input/outputs--as you explained to me some time ago--when performing A to D conversion at high-resolution sampling rates, more notably, using DSD format. I was doing precisely that, then, when I decided to switch from analog to USB and changed the source configuration, the DC error notice popped out... the thing is, at that instance, I had connected (and turned on) a new very powerful amplifier that I recently acquired. This amp is rated at 750 Watts RMS per channel (4 ohms), capable of 1200 watts peak (1% Distortion), and has a very high bandwidth. I use relatively large electrostatic speakers.

Matthias, could it be the case that an unusual "erroneous signal" was generated when the RME output source control cut off the analog input connection so that the corresponding current surge into such a powerful amplifier happened to trigger the DC protection mode? Now, why the error notice became permanent, requiring a factory reset to be eliminated, is a side question.

Goes without saying, thank you very much for jumping into this interesting issue (...no surprise you did).

Always your happy customer..................dr.larkos

  • KaiS
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Re: Error message "DC Detected Line Deactivated"

dr.larkos wrote:

… I had connected (and turned on) a new very powerful amplifier that I recently acquired. This amp is rated at 750 Watts RMS per channel (4 ohms), capable of 1200 watts peak (10% Distortion), and has a very high bandwidth. I use relatively large electrostatic speakers.

Be careful when overpowering speakers.

Electrostatic speakers are unforgiving in that regard, when a voltage spike caused arcing inside the panel or the step up transformers, they are permanently damaged.

I strongly recommend to either turn down the power amp’s input controls (if exist) or use passive attenuators to reduce that risk.

As a side effect a good level matching gains audio quality.


Here‘s how to find out the best setting, probably Case 2:
https://forum.rme-audio.de/viewtopic.ph … 21#p161721



CASE 2, digital volume control:

If you want to use ADI-2's digital volume control to set listening level, ADI-2 DAC / (Pro) has a clever option that increases the usable dynamic range by 18 / (20) dB: "Auto Reference Level":

• Switch ON ADI-2's "Auto Reference Level".
• Set ADI-2 DAC's (Pro's) volume control to -18 / (-20) dBr.  (1)
• Set ext. amp's volume control (or passive attenuators) slightly above your normal listening level.
• Use ADI-2's volume control to set the final listening level.

Now ADI-2 automatically adapts the reference level for best fit to your loudness demands, while maximizing it's DAC's dynamic range.

If your external amp does not have a volume control, use variable passive attenuators to fit the level:
https://forum.rme-audio.de/viewtopic.ph … 42#p120442

KaiS's Website

7 Reply by dr.larkos (edited by dr.larkos 2024-01-23 06:51:46)

  • Registered: 2017-05-04
  • Posts: 58

Re: Error message "DC Detected Line Deactivated"

Thank you, KaiS, for your thorough response. It is an excellent tutorial on component level-matching and dynamic range optimization issues and solutions. While I have been aware for quite some time of the main points in there, the tutorial provided a clear and complete perspective.
However, it so happens, that level-matching/dynamic range optimization issues and solutions are not quite the subject matter of my previous email (intended for Matthias). The subject matter and my concern are related to the issue dealt with in Chapter 34.9, in the RME ADI-2 Pro's "User's Guide"(version 3.8, the most recent version): "Noise Levels in Hi-Speed Modes," namely, high levels of noise when operating at high sampling rates...notably in DSD. The summary at the beginning of Chapter 34.9 is quoted immediately below.

QUOTE:
The outstanding signal-to-noise ratio of the ADI-2 Pro AD-converters can be verified even without expensive test equipment, by using record level meters of various software. But when activating higher sample rates, the displayed noise level will rise from -120 dBFS to -114 dBFS at 96 kHz, and –92 dBFS at 192 kHz. This is not a failure. The software measures the noise of the whole frequency range, at 96 kHz from 0 Hz to 48 kHz (RMS unweighted), and at 192 kHz from 0 Hz to 96 kHz.
When limiting the measurement range from 20 Hz to 20 kHz (so-called audio bandpass) the value would be -120 dB again. This can be verified with RME's DIGICheck. The function Bit Statistic & Noise measures the noise floor as Limited Bandwidth, ignoring DC and ultrasound.
UNQUOTE

The Guide's analysis of the rise in noise level stops at 192 kHz (-92 dBFS), I wonder how matters look when operating at 768 kHz, lower DSD territory (I believe). With no analog signal at all being fed, or even with no analog source whatsoever being connected, when the unit is set to perform in AD/DA mode at 768 kHz (PCM or DSD), in the Global Level Meter, the L/R columns for the Analog Input will show a strong ["Phantom," my depiction] signal that reaches about -42dB (peak, I believe, and of course containing no audible frequencies). Does this "phantom" signal contain DC components capable of triggering the Digi-2 Pro's DC protection feature when a very powerful/wide bandwidth amplifier is in the circuit? Particularly if when switching operating mode from AD/DA to USB this happens to generate a significant enough voltage spike? If the DC protection blocked the switching from AD/DA to USB, with a 768 kHz operating sampling rate and the "phantom" analog signal (shaped noise) still locked in, I surmise, that this could have been what kept the DC fault warning screen into a permanent stage...only a factory reset could comply with the demand from the DC protection feature to "remove the
erroneous signal to recover." Well, just surmising...

Cheers and all the best....................dr.larkos

8 Reply by KaiS (edited by KaiS 2024-01-23 10:48:54)

  • KaiS
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Re: Error message "DC Detected Line Deactivated"

1. The fact that if looking at a wider bandwidth, that covers signals far out of the audible band, the noise seen is proportionally greater, is understood?

This happens the exact same with EVERY audio device that is NOT band limited by itself.



2. And here we are at the 2nd question: why no measurement specs above 192 kHz sample rate:

Because ADI-2’s frequency response is in fact purposely band limited at PCM AD: 180 kHz / DA: 109 kHz (-3dB), see specs for 768 kHz sample rate.
So no significant change of outside-audible-band noise above 192 kHz sample rate.

BTW: DSD AD per definition doesn’t use filtering, so a DSD recording contains the full amount of the format’s inherent noise.
At DA this noise is partly filtered out then in the analog domain.

This soft-shaped filtering is urgently needed, even more so with DSD format, which has excessive noise components in a frequency range that typical speaker and headphone power amps can NOT handle at all.

ALL power amps are POWER band limited, usually somewhere around 50-100 kHz.
The reason: high-power transistors for audio are not fast enough to deliver the same power in HF range as in audio band.
Even the drive circuits have their limits which becomes visible in measurements of rising distortions vs. frequency for higher f.

What happens if such an amp is forced to amplify the mentioned noise:
It can’t deliver and distorts, and the intermodulation distortion products partly lay in the audible range.

This has to be avoided for a good sound.



3. If DC is present, it’s clearly visible in ADI-2’s Analyzer’s lowest band, that measures the DC-23 Hz range.

KaiS's Website