Topic: ADI-2 DAC: DC detected warning screen

Apologies if this or something similar has been asked before. I could not find it with my searches but I am not very familiar with this forum.

As described below, I get the "Warning exclamation point, DC detected, Phones deactivated, Pull out Phones plug to reset output state" warning message. A paragraph about this screen appears on page 31 of the manual. But why is it happening exactly?

It happened once a couple of months ago, and now again. I am not 100% sure, but I think the first time was the same sequence of events as this evening:

1) I turn on RME ADI-2 DAC FS (owned brand new since Dec 2018, updated to the latest firmware, excellent condition, zero issues)

2) I turn on my tube amp which is connected to RME via RCA cables

3) I plug in headphones and listen for 2-3 hours

4) I unplug from tube amp (zero volume and all that), turn off tube amp

5) I plug headphone jack into RME to listen directly via RME amp... I get the DC warning screen.

6) I try several times, same screen - it's as if it won't change automatically to headphones out from line out?

7) I wait 5 minutes, plug headphones in to the RME, now it works, no DC detected screen.

Does anyone know why this is happening? Someone suggested on the Head-Fi forum that the tube amp (Woo Audio WA3) could somehow be leaking current into the RME? I have zero technical knowledge in this area, so apologies if this is completely impossible. But if it is possible, should I be worried about damage to the RME? The tube amp is in mint condition and I have used it with multiple DACs without issues.

Thanks!

Re: ADI-2 DAC: DC detected warning screen

If this screen comes up on a regular base, e.g. after warmup, there is something broken.
Claim your warranty if possible.

Re: ADI-2 DAC: DC detected warning screen

No, it only came up after switching my headphones from the tube amp jack to the RME jack. I follow carefully the advised procedure for tube amps (mute system, volume 0, unplug headphone, turn off amp, then plug in to RME).

Re: ADI-2 DAC: DC detected warning screen

CaptainFantastic wrote:

No, it only came up after switching my headphones from the tube amp jack to the RME jack. I follow carefully the advised procedure for tube amps (mute system, volume 0, unplug headphone, turn off amp, then plug in to RME).

The tube amp has nothing to do with that.
The headphones cannot carry anything adverse to the ADI-2.

• Either this was a singularly event, caused i.e. by unloading a static electricity charge (like what you get if you wear synthetic cloth).
ADI-2’s fail sensing mechanism was reported to be triggered by that several times here.

• Or something is broken inside, causing DC offset or false alarm when ADI-2 is warmed up.
From you description, that you had to let cool down ADI-2 before you could use it again, I’d tend to this scenario.


If this is repeatable, get ADI-2 serviced.

Re: ADI-2 DAC: DC detected warning screen

Thank you very much for your responses.

Your answer was clear, but at the risk of insistence, you are sure nothing could be happening via the RCA cables from the tube amp to the RME ADI-2? Could current somehow be leaking that way either while the tube amp is running or after I turn it off? I know that RCA cables are clearly not designed for that, but technically it could happen?

I am only double-checking because this has ONLY happened on the two instances (months apart) when I decided my tube listening session was good for the day and it was time to switch to the RME amp.

As for warranty, I can't believe it is only 6 months from the manufacturer. Even with the extension of that to two years in my country, I am out of warranty since I bought it in December 2018. But the unit has been running flawlessly other than this.

6

Re: ADI-2 DAC: DC detected warning screen

The headphone output stage might have a problem. But you might also check if your source material (the playback signal) includes DC. You can do so with DIGICheck or any wave editor out there, but more easily with the ADI's own spectral analyzer. If the lowest band shows no constant level in Line Out mode, then there is no DC.

Regards
Matthias Carstens
RME

Re: ADI-2 DAC: DC detected warning screen

Thanks for the replies. The source is optical in via Asus Essence STX II card. No constant level in Line Out mode in the lowest band.

I guess I will just use it without the tube amp to be safe, or I will always wait a good 30 minutes between switching my headphones from the tube amp to the ADI-2 amp.

8 (edited by KaiS 2021-04-10 16:00:09)

Re: ADI-2 DAC: DC detected warning screen

CaptainFantastic wrote:

Thanks for the replies. The source is optical in via Asus Essence STX II card. No constant level in Line Out mode in the lowest band.

I guess I will just use it without the tube amp to be safe, or I will always wait a good 30 minutes between switching my headphones from the tube amp to the ADI-2 amp.

I can rest a-sure you, the tube amp switching on or off has nothing to do with that, there is no interlink back from ADI-2’s RCA to it’s headphones output, other than ground connection.


It’s a temperature related problem on ADI-2.

Test it without the tube amp connected, let ADI-2 warm up, plug in the headphones ... I guess you get the screen – if it’s a persistent effect.

9 (edited by liquid_mercury 2021-11-04 23:44:19)

Re: ADI-2 DAC: DC detected warning screen

I have had this exact problem today with my brand new RME ADI-2 DAC FS that arrived today. I received the message "DC detected. Phones deactivated, Pull out Phones plug to reset output state" and I thought how could this happen. I use a Beyerdynamic DT880 at 600ohm impedance and Hi Power setting on the dac with about -8dBr and windows sound to max.

As the error occured more frequently during my testing I thought that I need to do a research to find what was causing this error. I experienced the error at most when I played a song in VLC Player and then pressed "Stop" button in the player. As Matthias said above I noticed that on the lowest band in the spectral analyzer the green bar did not move down to zero but instead kept holding it's value. I unplugged several cables to see when the bar was going down. After I unplugged the SPDIF optical cable the bar immediately went down to zero.

Can SPDIF Optical transport a DC to an external device?

To test this issue further I unplugged the SPDIF Optical from my soundcard which is a Xonar Essence STX that has been running for quite some years in the PC and plugged the optical cable into the SPDIF socket of my mainboard instead. After I did so I have not yet received DC inputs to the Dac. I would assume that my xonar essence is slowly dying?? Could this be the case?

Also last time I checked the soundcard's headphone amp the sound was really heavily distorted. It was horrible...

Hopefully my research has fixed this error finally and I hope that my ADI-2 did not get any damage from the DC input.

Since I am not too deep into the technical aspect of sound enginerring, could anybody confirm that my assumption was right? And the soundcard was the one to blame here?

10 (edited by KaiS 2021-11-05 01:31:04)

Re: ADI-2 DAC: DC detected warning screen

liquid_mercury wrote:

.... I received the message "DC detected. Phones deactivated, Pull out Phones plug to reset output state" and I thought how could this happen.
...
I experienced the error at most when I played a song in VLC Player and then pressed "Stop" button in the player. ... I noticed that on the lowest band in the spectral analyzer the green bar did not move down to zero but instead kept holding it's value. I

....After I unplugged the SPDIF optical cable the bar immediately went down to zero.

Can SPDIF Optical transport a DC to an external device?

...I unplugged the SPDIF Optical from my soundcard which is a Xonar Essence STX that has been running for quite some years in the PC and plugged the optical cable into the SPDIF socket of my mainboard instead. After I did so I have not yet received DC inputs to the Dac.

SPDIF can carry DC.

Once you stop playback of an audio file, the last value transfered usually is a random DC signal.
Therefor a “Mute” command needs to be executed on stop, and handled by the driver/hardware.

My guess is, the Xonar Essence either has a driver issue or your assumption is right, it‘s broken.
Install another Xonar driver / firmware.


liquid_mercury wrote:

I use a Beyerdynamic DT880 at 600ohm impedance and Hi Power setting on the dac with about -8dBr and windows sound to max.

You‘re definitely listening way too loud, you permanently damage your hearing capability.

I assume you send 100% level to ADI-2 (check with RME Bittest).

On your Beyerdynamic DT880 600 Ohm you should listen no higher than about -28 dBr with contemporary Popmusic, -24 dBr with typical Jazz, -15 dBr with typical Classical.

Personally I‘m just listening with my DT880 600 Ohm through one of my mixed playlists on -31 dBr, without any feel to need bringing this up.

11 (edited by ning 2021-11-05 06:33:51)

Re: ADI-2 DAC: DC detected warning screen

Take a look at the left most bar in your spectrum analyzer. If you see it having a high value, then listening with a high volume will trigger dc protection.

Sometimes music are not mastered correctly. So it’s not ADI-2’s fault. The design works as intended to protect your headphones. Your music is the problem.


ADI-2 is not perfect though. The DC protection does not work in balanced phone mode at all if the music has DC. I never tried it but based on my understanding of the circuit that should be the case. I hope MC could put a warning in the manual if that is the case.

12 (edited by KSTR 2021-11-05 09:12:50)

Re: ADI-2 DAC: DC detected warning screen

The sensing for DC is done in analog at the output of the HP amp, and L and R channel outputs are summed for simplicity. The DC protection is meant to help in case of a catastrophic failure in the hardware path from DAC chip output to HP jack where it is unlikely that two offsets would appear with identical magnitude but opposite sign.

It of course also reacts to DC in the signal.... unless it's completely canceling in the L + R sum. This means in balanced phones mode on the Pro there is no DC protection for signal DC (but still for hardware DC).

As mentioned, always look at the lowest bar in the spectrogram display first, if it still shows some level with music off/paused then the DAC is receiving a DC signal.

Re: ADI-2 DAC: DC detected warning screen

Right, that's the same conclusion I reached after looking at the circuit. It just happened that DC from music will be doubled in the balanced headphone output architecture but get canceled out in the detection circuit. So it's not protected against ill-mastered music.

I hope MC either document that in the manual, or implement this protection in software.

Re: ADI-2 DAC: DC detected warning screen

liquid_mercury wrote:

I use a Beyerdynamic DT880 at 600ohm impedance and Hi Power setting on the dac with about -8dBr and windows sound to max.

KaiS wrote:

You‘re definitely listening way too loud, you permanently damage your hearing capability.

I assume you send 100% level to ADI-2 (check with RME Bittest).

On your Beyerdynamic DT880 600 Ohm you should listen no higher than about -28 dBr with contemporary Popmusic, -24 dBr with typical Jazz, -15 dBr with typical Classical.

Personally I‘m just listening with my DT880 600 Ohm through one of my mixed playlists on -31 dBr, without any feel to need bringing this up.

Thanks for the heads-up. Yes, windows sound volume is set to 100. SPDIF input to the dac is set to 96khz/24bit. I mostly listen to metal music and I tried your loudness setting on the dac. -30dbr up to -25dbr is okay in Hi Power mode though I was missing the punch at first. After a while of listening you get used to it I guess. I will definitely try to be more cautious not to turn the volume up too loud. I haven't had any issues with my hearing though I will make a professional hearing test just to make sure everything is alright. Thanks again to let me know!

15 (edited by KaiS 2021-11-05 10:03:13)

Re: ADI-2 DAC: DC detected warning screen

ning wrote:

So it's not protected against ill-mastered music.

Even “ill-mastered“ music does not contain enough DC to be of any concern, or to be capable of breaking headphones.
At least I’ve never seen such that is triggering ADI-2’s DC protection.

The case described by liquid_mercury is clearly hardware/driver related, as the same music played through another path does work.

Re: ADI-2 DAC: DC detected warning screen

Is there any way to tell or calculate the outgoing decibel value from the headphones to the ears?

17 (edited by ramses 2021-11-05 15:44:49)

Re: ADI-2 DAC: DC detected warning screen

liquid_mercury wrote:

Is there any way to tell or calculate the outgoing decibel value from the headphones to the ears?

I think not because different speakers of different headphones have different levels of efficiency and thus loudness to the ear.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13

18

Re: ADI-2 DAC: DC detected warning screen

KaiS wrote:
ning wrote:

So it's not protected against ill-mastered music.

Even “ill-mastered“ music does not contain enough DC to be of any concern, or to be capable of breaking headphones.
At least I’ve never seen such that is triggering ADI-2’s DC protection.

That's correct. The worst PCM DC that you find is in recordings from early generation ADCs, like in DAT recorders. It's around -50 dBFS. +28 dBu (max level balanced, highly unrealistic) -50 dB = -22 dBu = + or - 0.085 V DC. That's just 85 millivolt. The protection circuit will not engage because this DC level is irrelevant, even for the most sensitive IEM.

I don't see where out-of-phase DC in significant levels should come from. In case of a hardware defect (the main purpose of this protection circuit) such out-of-phase DC is near impossible to happen.

Regards
Matthias Carstens
RME

19 (edited by ning 2021-11-05 15:06:31)

Re: ADI-2 DAC: DC detected warning screen

Ramses and MC. There surely are albums that is mixed very poorly. Just Google and you will find quite a few notorious ones. See for instance this post:https://www.audiosciencereview.com/foru … ost-776805 and this follow up https://www.audiosciencereview.com/foru … ost-776892

This track can successfully put ADI-2 into protection mode for single ended headphone output. It’s easy to guard against these with software in balanced mode and it won’t take too much effort — as you mentioned here, simple calculation is enough.

20 (edited by ramses 2021-11-05 15:45:53)

Re: ADI-2 DAC: DC detected warning screen

ning wrote:

Ramses and MC. There surely are albums that is mixed very poorly. Just Google and you will find quite a few notorious ones. See for instance this post:https://www.audiosciencereview.com/foru … ost-776805 and this follow up https://www.audiosciencereview.com/foru … ost-776892

This track can successfully put ADI-2 into protection mode for single ended headphone output. It’s easy to guard against these with software in balanced mode and it won’t take too much effort — as you mentioned here, simple calculation is enough.

My answer was regarding post #16, I added a quote now to make it clear.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13

Re: ADI-2 DAC: DC detected warning screen

Oh sorry ramses I misread.  was supposed to reply KaiS and MC. My apologies . I was reading using my smartphone and the screen is too small.

Re: ADI-2 DAC: DC detected warning screen

ning wrote:

Oh sorry ramses I misread.  was supposed to reply KaiS and MC. My apologies . I was reading using my smartphone and the screen is too small.

No problem wink

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13

Re: ADI-2 DAC: DC detected warning screen

To cope with DC in recordings one could simply add a 20Hz HighPass in the EQ section, DC and useless ultra low frequency removed.

24 (edited by ning 2021-11-06 01:59:20)

Re: ADI-2 DAC: DC detected warning screen

that occupies one band of eq. why not just implement a software protection? dc amplitude is already calculated and firmware just needs to add the logic to kick this in.

25 (edited by KaiS 2021-11-06 02:35:34)

Re: ADI-2 DAC: DC detected warning screen

ning wrote:

Ramses and MC. There surely are albums that is mixed very poorly. Just Google and you will find quite a few notorious ones. See for instance this post:https://www.audiosciencereview.com/foru … ost-776805 and this follow up https://www.audiosciencereview.com/foru … ost-776892

This track can successfully put ADI-2 into protection mode for single ended headphone output. It’s easy to guard against these with software in balanced mode and it won’t take too much effort — as you mentioned here, simple calculation is enough.

The track has a huge (and varying) amount of of DC, up to -9 dBFS, even streamed at Tidal,.
Seems you can find all types of stupidity if you only search enough.

ning wrote:

... why not just implement a software protection? dc amplitude is already calculated and firmware just need to add the logic to kick this in.

Why built a compensation for stupidity?

The implementation of DC removal is by no means trivial (aside from a 2 Hz highpass filter).
I.e. on the mentioned track at 0’30” -13dBFS DC kicks in, at 0’51” DC changes to -9 dBFS,  2’30” the DC suddenly disappears.
How to handle this?

26 (edited by ning 2021-11-06 03:18:32)

Re: ADI-2 DAC: DC detected warning screen

KaiS wrote:

Why built a compensation for stupidity?

The implementation of DC removal is by no means trivial (aside from a 2 Hz highpass filter).
I.e. on the mentioned track at 0’30” -13dBFS DC kicks in, at 0’51” DC changes to -9 dBFS,  2’30” the DC suddenly disappears.
How to handle this?

No. I'm NOT calling for a DC removal feature. I'm calling for adding a software solution for DC PROTECTION --- shutting off the headphone output if DC is detected. The current ADI-2 implementation is solely hardware based and while this works well in single ended mode (except for specifically crafted track, such as left has + dc and right has - dc), it failed in balanced headphone mode if music has DC.

Implementing such protection is pretty trivial --- the firmware already calculates the current digital signal's DC amplitude in runtime --- that's how the leftmost bar in the spectrum is calculated.

Then we can calculate the final DC amplitude in dbu after DSP (volume, eq, etc) by simply adding/subtracting. say signal DC is -10dbfs and the volume is at -5dbfs, then dc value is at -15dbfs. for cases where the headphone amp is at high power balanced mode (+28dbu), the dc is  28-15=+13dbu.

If that final dc amplitude is larger than certain value, say 5dbu, then shut off the relay and display the "DC detected" screen.

it doesn't really matter which part of your track has DC. the protection should just kick in when the current digital signal has good amount of DC.

27

Re: ADI-2 DAC: DC detected warning screen

That's not correct. The left bar in the Analyzer is the whole band from 0 to 25 Hz. Mentioned in the manual. It's on near full level on mine most of the time (I like music with a lot of subbass).

The 'DC' in the example catastrophy (unbelievable) is part of the used bass synth. It's indeed a DC error as long as the bass is active.

> that occupies one band of eq.

Sure. But High Pass filter in the PEQ has been added especially for such use cases, so that is no argument in my view.

Regards
Matthias Carstens
RME

Re: ADI-2 DAC: DC detected warning screen

My understanding is if the output is too high and clips, it creates a flat wave top that equals to a DC, that hurts speaker and heaphone......

Pacifist, dumb, not stupid
Listen music out from a box which sounds
Reading words on paper/ screen

29 (edited by KaiS 2021-11-06 08:16:58)

Re: ADI-2 DAC: DC detected warning screen

Johannes AU wrote:

My understanding is if the output is too high and clips, it creates a flat wave top that equals to a DC, that hurts speaker and heaphone......

This flat top audio wave is (steady) DC, but only for a short moment, until it sways back to the opposite polarity.

Same is true for EVERY half-wave of AC (audio).
So in fact it’s not, as you have to watch longer periods of signal to detect DC, at least 0.5-1s for the audio band.


Asymetrical (one sided) clipping causes some amounts of DC with asymmetrical waveforms, typically voice or brass instruments.

But you have to keep in mind, clipping is an untypical state for audio.

30 (edited by Johannes AU 2021-11-06 10:06:23)

Re: ADI-2 DAC: DC detected warning screen

KaiS wrote:
Johannes AU wrote:

My understanding is if the output is too high and clips, it creates a flat wave top that equals to a DC, that hurts speaker and heaphone......

This flat top audio wave is (steady) DC, but only for a short moment, until it sways back to the opposite polarity.

Same is true for EVERY half-wave of AC (audio).
So in fact it’s not, as you have to watch longer periods of signal to detect DC, at least 0.5-1s for the audio band.


Asymetrical (one sided) clipping causes some amounts of DC with asymmetrical waveforms, typically voice or brass instruments.

But you have to keep in mind, clipping is an untypical state for audio.

Thank you for the additional information, KaiS :-)

So, too loud a volume which creates/prolongs the cliping is not a healthy thing, (or in other words, a steady tone which is too high and last more than 0.5-1s is no good) right? Or, may be the RME DC protection does provide further function not only for clipping?

Pacifist, dumb, not stupid
Listen music out from a box which sounds
Reading words on paper/ screen

31 (edited by ning 2021-11-07 02:47:03)

Re: ADI-2 DAC: DC detected warning screen

> So, too loud a volume which creates/prolongs the cliping is not a healthy thing, (or in other words, a steady tone which is too high and last more than 0.5-1s is no good) right?

Clipping will make the signal distorted so it is not good --- it does not sound good in the first place.

> Or, may be the RME DC protection does provide further function not only for clipping?

Clipping has nothing to do with DC. They are two different things... Having a too high steady tone (let's say 50kz sine wave with no DC offset) that last long will not produce DC --- you get square wave instead of DC. The DC offset of that square wave is still 0.

Fried headphone amplifier opamp will also produce DC. Depending on which op amp is broken the result may be different. There is one 1688 driving the other 5. If it's one of the 5, the others can correct it back (but produce a lot of heat, which will trigger overcurrent protection discussed in the next paragraph). but if it's the first one, the whole circuit will produce full DC output and the protection circuit will shut off the output immediately.

RME does offer over current protection. There are thermistors inside the unit (one per rail, so two per channel) which measure the temperature and voltage in real time. There are 8 (in Pro) or 4 (in DAC) channels of comparators working simultaneously, and will either lower your volume or stop the output when you try to play too high level for low impedance headphones.

32 (edited by KSTR 2021-11-06 11:48:42)

Re: ADI-2 DAC: DC detected warning screen

The only correct way to deal with DC in recordings is to remove it (with the 20Hz HighPass, or equivalent filter in your playback software).

Any attempt to trigger a 'fail-safe" DC protection based on signal analysis and knowledge of levels is doomed to fail... you'd need to know all parameters of the connected headphone in all detail to dial in the correct limits and algorithms to protect a phone from DC damage (fried coils) but not overly restrict low frequency / DC max allowable output. And while we're at it, why not use that knowledge to also engage volume limiters to protect the phone from destruction from too high input?

All of that is impossible for reasons immediately obvious.

RME has implemented a scheme which is IMHO a good compromise in all regards.
- The hardware protection features are the last fence and are implemented well (also for brutal overload/shorts). For the pessimists, use outboard AC-coupling caps ;-)
- Set up a digital HighPass filter in the device -- or in the source playback if you don't want to "waste" an onboard filter -- and you're all set and well protected for 99.99% of scenarios. Problem solved.

33 (edited by KaiS 2021-11-06 15:44:08)

Re: ADI-2 DAC: DC detected warning screen

Johannes AU wrote:
KaiS wrote:
Johannes AU wrote:

My understanding is if the output is too high and clips, it creates a flat wave top that equals to a DC, that hurts speaker and heaphone......

This flat top audio wave is (steady) DC, but only for a short moment, until it sways back to the opposite polarity.

Same is true for EVERY half-wave of AC (audio).
So in fact it’s not, as you have to watch longer periods of signal to detect DC, at least 0.5-1s for the audio band.


Asymetrical (one sided) clipping causes some amounts of DC with asymmetrical waveforms, typically voice or brass instruments.

But you have to keep in mind, clipping is an untypical state for audio.

Thank you for the additional information, KaiS :-)

So, too loud a volume which creates/prolongs the cliping is not a healthy thing, (or in other words, a steady tone which is too high and last more than 0.5-1s is no good) right? Or, may be the RME DC protection does provide further function not only for clipping?

You haven’t got me right.
You asked, so my point was to explain how DC can be generated from clipping an audio signal.

Clipping per se hits at a level limit.
It will not damage ADI-2, but being loud enough it can destroy headphones, speakers, and you valuable hearing, with or without extra DC.
And hey - it doesn’t sound good usually!


High value of DC is a problem for headphones and speakers, as the voice coil is heated by the current, but not moving, so there is less air flow cooling happening.


ADI-2 Pro’s DC Protection:
According to my measurements ADI-2’s DC protection protects connected headphones from internal component failure, but not 100% from signals like the stupid track mentioned.

I did NOT measure by connecting headphones smile, but using load resistors and the music track - BLOC PARTY Blue Light (Engineers ‘Anti-Gravity’ Mix) - from 1’00”.
https://tidal.com/track/86125589


Measurement of ADI-2 Pro’s DC Protection characteristics:
Load/Ohm •  DC/V • Time/s •  dBr • Power/mW

No Load • 0.9V • 15s • -14,5 dBr • 0.00mW

47R • 2.4V •  2 s • -6.0 dBr • 122mW
47R • 1.5V •  4 s • -10.0 dBr • 48 mW
47R • 0.9V • 15s • -14.5 dBr • 17 mW
47R • 0.8V • 52s • -15.5 dBr
47R • 0.7V • >100s • -16.5 dBr • 10 mW


16R • 2.4V •  2 s •  -6.0 dBr • 360 mW
16R • 1.5V •  4 s • -10.0 dBr • 140 mW
16R • 0.9V • 15s • -14.5 dBr
16R • 0.8V • 52s • -15.5 dBr

Conclusion:
Most 47 Ohms headphones can stand 122 mW for 2 s, but some more delicate, i.e. 16 Ohms IEMs, can’t stand 360 mW for 2s.

ADI-2 Pro’s DC Protection is DC-Voltage/Time dependent only, the connected headphones impedance has no influence.

Re: ADI-2 DAC: DC detected warning screen

Thank you ning and KaiS, now I got it :-)

Pacifist, dumb, not stupid
Listen music out from a box which sounds
Reading words on paper/ screen

35 (edited by ning 2021-11-07 03:18:29)

Re: ADI-2 DAC: DC detected warning screen

KaiS is right in “ ADI-2 Pro’s DC Protection is DC-Voltage/Time dependent only, the connected headphones impedance has no influence.”

It works by charging a capacitor. When it has enough voltage the three bjts (to make sure it works for both positive and negative) next to it will trigger the protection.  So takes time and enough voltage. The circuit is not connected to the headphone attached so headphone impedance does not matter.

Also, for testing, you don't need that track mentioned earlier in the post. Any DAW or audio programming platform can give you pure DC easily. For instance, in SuperCollider, "{Pulse.ar(0)}.play;" can give you full amplitude DC.
in addition to that, "{Pulse.ar(0.0)*[1,-1]}.play;" should give you full positive amplitude DC in the left channel and full negative amplitude DC in the right channel => A signal that specifically crafted to make DC protection not able to handle.

36

Re: ADI-2 DAC: DC detected warning screen

ADI-2 Pro’s DC Protection:
According to my measurements ADI-2’s DC protection protects connected headphones from internal component failure, but not 100% from signals like the stupid track mentioned.

I did NOT measure by connecting headphones smile, but using load resistors and the music track - BLOC PARTY Blue Light (Engineers ‘Anti-Gravity’ Mix) - from 1’00”.
https://tidal.com/track/86125589


Measurement of ADI-2 Pro’s DC Protection characteristics:
Load/Ohm •  DC/V • Time/s •  dBr • Power/mW

No Load • 0.9V • 15s • -14,5 dBr • 0.00mW

47R • 2.4V •  2 s • -6.0 dBr • 122mW
47R • 1.5V •  4 s • -10.0 dBr • 48 mW
47R • 0.9V • 15s • -14.5 dBr • 17 mW
47R • 0.8V • 52s • -15.5 dBr
47R • 0.7V • >100s • -16.5 dBr • 10 mW


16R • 2.4V •  2 s •  -6.0 dBr • 360 mW
16R • 1.5V •  4 s • -10.0 dBr • 140 mW
16R • 0.9V • 15s • -14.5 dBr
16R • 0.8V • 52s • -15.5 dBr

Conclusion:
Most 47 Ohms headphones can stand 122 mW for 2 s, but some more delicate, i.e. 16 Ohms IEMs, can’t stand 360 mW for 2s.

ADI-2 Pro’s DC Protection is DC-Voltage/Time dependent only, the connected headphones impedance has no influence.

You make it look like there is an issue with DC protection, disregarding that no one in his sane mind would use IEMs in high power mode with volume cranked up! That is a ridiculous use example. Same for the other bold ones - unrealistic volume settings. Low impedance phones are usually super-effcient, so are used at much lower settings or even in low power mode, or they can stand many watts (low sensitivity planars etc).

And that you now give a bluecopy on how to endanger the user's equipment is a really bad idea...

Regards
Matthias Carstens
RME

Re: ADI-2 DAC: DC detected warning screen

Haha calm down, KaiS probably just want to  toy with the device:)

38

Re: ADI-2 DAC: DC detected warning screen

KaiS knows what he does and doesn't need instructions...

Regards
Matthias Carstens
RME

39 (edited by KaiS 2021-11-08 10:42:08)

Re: ADI-2 DAC: DC detected warning screen

I should have written a disclaimer:

DON‘T DO THIS AT HOME
The following was done by experienced professionals under controlled conditons.

As I demonstrated, ADI-2 does a good job protecting typical headphones from DC.

So we have:
• DC protection.
• There is a warning screen when plugging ‘phones with Hi-Power active.
• The level is slowly ramped up once ‘phones are plugged in.
So the user has an option to unplug or stop playback before the level becomes dangerous - for the headphones or the ears!

A lot of protection measures, and much more than other headphone amps do offer.


But - there is such a great variety of headphones out there that it’s not possible baby all of them.

Not to forget, one can simply break headphones or speakers by playing them too loud.


Finally:
I could imagine, an optional 2 Hz (or tuneable) 1st order low cut would be a nice addition.
As ADI-2 is used for mastering, or directly connected to a speaker amp this could i.e. fix tracks like the one above, or protect speakers where no other option exists.

Re: ADI-2 DAC: DC detected warning screen

KaiS wrote:

I should have written a disclaimer:

DON‘T DO THIS AT HOME
The following was done by experienced professionals under controlled conditons.

As I demonstrated, ADI-2 does a good job protecting typical headphones from DC.

So we have:
• DC protection.
• There is a warning screen when plugging ‘phones with Hi-Power active.
• The level is slowly ramped up once ‘phones are plugged in.
So the user has an option to unplug or stop playback before the level becomes dangerous - for the headphones or the ears!

A lot of protection measures, and much more than other headphone amps do offer.


But - there is such a great variety of headphones out there that it’s not possible baby all of them.

Not to forget, one can simply break headphones or speakers by playing them too loud.


Finally:
I could imagine, an optional 2 Hz (or tuneable) 1st order low cut would be a nice addition.
As ADI-2 is used for mastering, or directly connected to a speaker amp this could i.e. fix tracks like the one above, or protect speakers where no other option exists.

True, like one of the gentleman here, I forgot is you or ning or ramses reminds me not to instruct people doing the ground plug too :-)

Pacifist, dumb, not stupid
Listen music out from a box which sounds
Reading words on paper/ screen

Re: ADI-2 DAC: DC detected warning screen

Dear all,
I have had an ADI-2 DAC FS (ESS chip) for a few weeks now. Last night while listening to music I saw the following message appear: DC detected Phones deactivated Pull out phones plug to reset output state.
Since then the ADI has not worked. Whichever headphone I plug in, I always get the same message, even if I am not listening to music and the volume is at 0.
I tried restarting the computer and the ADI, but nothing worked.
I have 2 headphones, HIFIMAN Arya Stealth and a Sennheiser momentum. The problem occurs with both headphones. In fact I will tell you that the problem does not depend on the headphones. All I must do is insert a 3.5 to 6.5 conversion jack into the phones socket and I get the same error.

What can I do to be able to listen to music again?

Thanks for your help.

Gianluca

Re: ADI-2 DAC: DC detected warning screen

gianluca.coppola wrote:

...I saw the following message appear: DC detected Phones deactivated Pull out phones plug to reset output state.
Since then the ADI has not worked. Whichever headphone I plug in, I always get the same message, even if I am not listening to music and the volume is at 0.

Your ADI-2 DAC is broken, send it in for repair.
If you’re under warrenty, ask for a replacement.

BTW: The IEM out should still work, but that’s not a solution.

Re: ADI-2 DAC: DC detected warning screen

KaiS wrote:
gianluca.coppola wrote:

...I saw the following message appear: DC detected Phones deactivated Pull out phones plug to reset output state.
Since then the ADI has not worked. Whichever headphone I plug in, I always get the same message, even if I am not listening to music and the volume is at 0.

Your ADI-2 DAC is broken, send it in for repair.
If you’re under warrenty, ask for a replacement.

BTW: The IEM out should still work, but that’s not a solution.


Thank you for your quick reply.
it's really sad that such an amplifier breaks down after not even 2 weeks doing what it's supposed to do, amplify.
PS: even line out connection with an external amplifier (ROTEL) is not working.
I'm trying to contact the German seller.

44 (edited by KaiS 2022-06-16 23:30:30)

Re: ADI-2 DAC: DC detected warning screen

Just bad luck, not the norm.
May happen.
Don’t go to the Casino these days smile

Electronics tend to have a higher failure rate within the first few month of use, then stabilize, and only when they become very old the failure rate rises again.

Exemption: parts that have to handle high voltages an/or high currents close to their max. specs, like in bad designed Switched Mode Power Supplies.