1 Topic by m.holmes (edited by m.holmes 2022-01-07 16:44:24)

  • Registered: 2021-06-30
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Topic: Digital DC protection triggering?

Hello forum,

I found a song that triggers the DC protection on ADI-2 DAC when played via usb.
for the curious: it' track 10 from
https://www.discogs.com/release/1001335 … hen-Hippel
which is freely available from here:
https://www.germanremixgroup.de/content … wnload=160

Now, in my case the "fix" was pretty easy: I just recomputed ReplayGain for the song, and it now plays through.
(is this expected?).

However stopping playback entirely seems quite a drastic choice: maybe we could have an option in firmware to just -say- display a huge warning on the screen and keep on playing temporarily in a safe way? e.g. auto-lower the volume or filter some frequencies out?

all the best

2 Reply by Curt962 (edited by Curt962 2022-01-07 17:11:20)

  • Registered: 2019-01-07
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Re: Digital DC protection triggering?

Stopping Playback isn't so drastic when expensive gear downstream is at risk. 

You have the option of turning Digital DCP off, but that is neither advised, nor wise.  *an exception might be in a Lab Test environment where Test Signals may contain DC.

Refer to your User Manual (rev 2.9, Pgs 68/69) for a more thorough explanation of the DCP system.

An easy, and unobtrusive method of dealing with offending sources is to incorporate a simple High Pass Filter at 20hz in your PEQ as described by MC (RME) quite recently.

Curt

Vintage 2018 ADI-2 DAC. "Classic AKM4490 Edition"
Cables:  Red, and White Ones.
Speakers:  Yes
  • waedi
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Re: Digital DC protection triggering?

The song needs remastering process at lower volume.
It is clipping constantly at plus 0.7 dB true peak, measured with Youlean Loudness meter.
you can lower the gain of your play software ?

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue
  • Registered: 2021-06-30
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Re: Digital DC protection triggering?

Curt962 wrote:

Stopping Playback isn't so drastic when expensive gear downstream is at risk.

You definitely don't want to damage your hardware, but you might think of different countermeasures -say- "dim" the volume down to a safe level and keep on playing.


Curt962 wrote:

An easy, and unobtrusive method of dealing with offending sources is to incorporate a simple High Pass Filter at 20hz in your PEQ as described by MC (RME) quite recently.

Right, but I don't want to do that permanently. As the dac knows exactly when to engage the protection, I'd find it quite natural to have an option specifying what the reaction should be (e.g. instead of dc protection on/off, I'd like to have: stop playback / dim volume / high pass filter / off)

  • Registered: 2021-06-30
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Re: Digital DC protection triggering?

waedi wrote:

The song needs remastering process at lower volume.
It is clipping constantly at plus 0.7 dB true peak, measured with Youlean Loudness meter.
you can lower the gain of your play software ?

yes, in fact just applying replaygain is an effective fix.

6 Reply by MC

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Re: Digital DC protection triggering?

The most effective fix is planned for the next firmware update. Until then you can turn off the Digital DC protection and only get the message, but not the mute.

Regards
Matthias Carstens
RME

MC's Website

7 Reply by KSTR (edited by KSTR 2022-01-07 21:17:26)

  • KSTR
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Re: Digital DC protection triggering?

https://abload.de/img/dc-offset6wk40.gif
This what's left when the track is steeply lowpass-filtered at 1Hz! (8th order)

No wonder it triggers the protection as the DC-levels are significant (-27dBFS == 4% of FullScale) plus useless infrasonic content.

Extemely bad recording and mastering at work.

  • KSTR
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Re: Digital DC protection triggering?

MC wrote:

The most effective fix is planned for the next firmware update.

I'm curious... a switchable infrasonic highpass-filter?

  • Registered: 2021-06-30
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Re: Digital DC protection triggering?

KSTR wrote:

No wonder it triggers the protection as the DC-levels are significant (-27dBFS == 4% of FullScale) plus useless infrasonic content.

Extemely bad recording and mastering at work.

Thanks for the analysis.
Let me state explicitly: I'm not saying that this song is a "false positive" of some sort.
My concern is a bit different: after installing the firmware update, it took less than 24 hours to trigger the DC protection warning.
I admit I didn't compute the probability, but from these numbers the issue doesn't seem "uncommon" and -if this is true- I strongly feel that a more "forgiving" workaround is required.
Otherwise users will perceive the "protection" as an annoyance, and just turn it off (which is bad).

  • Registered: 2021-06-30
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Re: Digital DC protection triggering?

KSTR wrote:
MC wrote:

The most effective fix is planned for the next firmware update.

I'm curious... a switchable infrasonic highpass-filter?

No need to say, I'm curious too...

  • KaiS
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Re: Digital DC protection triggering?

m.holmes wrote:
KSTR wrote:
MC wrote:

The most effective fix is planned for the next firmware update.

I'm curious... a switchable infrasonic highpass-filter?

No need to say, I'm curious too...

Usually I don’t like speculations but this time I can’t hesitate to give a bet:

As the new DC protection measures the DC content of the audio signal it might be a DC-servo function that nulls DC output.

KaiS's Website

12 Reply by ning (edited by ning 2022-01-08 07:33:34)

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Re: Digital DC protection triggering?

Yes that’s pretty simple and straightforward to implement.

Here's an example: https://www.xilinx.com/support/document … /wp279.pdf

RME already did the heavy lifting part in the last firmware update. the remaining is simple

13 Reply by Johannes AU (edited by Johannes AU 2022-01-08 10:37:50)

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Re: Digital DC protection triggering?

Good Morning from Hongkong.

Could be I am the first one encountered the Digital DC protection during the pre-test session, within 30-40 minutes of internet radio.

We do not know the recording is bad before, and play it loud, possibly damaged something and never know the cause and live with it, now this new function let us know and can protect downstream equipment, not bad at all. I think that is a good feature, though a bit trouble for some applications.

If let it off, the warning screen still shows, audio goes on, feel even worse after saw the warning screen, who can live with knowing something bad happens and let it stay and keep on listening?

A more forgiving protection or turning it off, it reminds me the name of a tennis star, or put a copper bar instead of a fuse.

Let's wait for the next firmware, I am confident MC and the RME team will find the best way to make it works in a better way.

Use the first aid MC recommended and kindly be patient for the next update. smile

Pacifist, dumb, not stupid
Listen music out from a box which sounds
Reading words on paper/ screen
  • Registered: 2021-06-30
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Re: Digital DC protection triggering?

ning wrote:

RME already did the heavy lifting part in the last firmware update. the remaining is simple

that was my point too.

  • Registered: 2019-02-13
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Re: Digital DC protection triggering?

I also came across a song with the same problem. If you have it downloaded locally, you can use Effect>Normalise in Audacity. First apply the DC offset. If the song keeps triggering the DC warning, keep lowering the gain until the warning disappears. Export the new file and good job, you are better at mastering than the sound engineers themselves.

  • eobet
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Re: Digital DC protection triggering?

Here's a track which triggers it:

https://dimaquiet.bandcamp.com/track/altitude-realtime

(Turns out, quite a number of "chiptune", ie old computer generated music using square, triangle and sawtooth waves in various distorted ways, triggers the DC protection so with that type of music it's apparently not that uncommon.)

17 Reply by KaiS (edited by KaiS 2024-11-26 23:28:37)

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Re: Digital DC protection triggering?

eobet wrote:

Here's a track which triggers it:

https://dimaquiet.bandcamp.com/track/altitude-realtime

(Turns out, quite a number of "chiptune", ie old computer generated music using square, triangle and sawtooth waves in various distorted ways, triggers the DC protection so with that type of music it's apparently not that uncommon.)

Just a reminder:
ADI-2 offers a filter that removes the DC problem before it damages anything:
I/O / xx Output xx/ Settings / Dig, DC Protection: Filter

This way even heavily DC polluted tracks can be played.

The filter is way below the audible range, doesn’t negatively affect the sound.

KaiS's Website