Topic: ADI 2 Pro FS Overload/Short Detected

Hello,

I've been having an issue with my ADI 2 Pro FS that I don't fully understand and hope someone can help me with.

First a quick description of my setup:

PC Mainboard native USB > ADI 2 Pro PH 3/4 > Sennheiser HD800S with included unbalanced cable

Firmware/Drivers are up to date


The issue I have is that when I turn on the DAC and listen to music/watch videos/play games I will get the Overload/Short Detected warning message after about 3 hours of use every time. At that point I have to turn off the DAC and back on. However, the device is quite hot to the touch at this point and if I immediately turn the device back on it will only take a few minutes for the same warning message to re-appear. If I choose to wait for 5-10 minutes before turning it back on then I will be able to use the DAC for about an hour before getting the error. If I end my computer session for the day and return on the next day I will be able to use it for 3 hours before the error message appears.

This is inconvenient for me because I tend to use my PC for 6-8 hours per sitting, meaning the first three hours are fine, but then I need to turn off the DAC every hour, wait 5-10 minutes with no sound/music playing until I end my session.

I don't really understand what causes this problem although if I had to take a guess it seems overheating related, but I'm really not sure.

Does anyone know what causes this issue and how I can fix it? Please let me know if you need me to provide more information.

2

Re: ADI 2 Pro FS Overload/Short Detected

Please return the ADI-2 Pro FS for service or exchange. The phones output is malfunctioning, causing both the heat and the shutdown.

Regards
Matthias Carstens
RME

Re: ADI 2 Pro FS Overload/Short Detected

MC wrote:

Please return the ADI-2 Pro FS for service or exchange. The phones output is malfunctioning, causing both the heat and the shutdown.

Oh I see. Thanks for the quick reply! Should I contact the merchant or RME itself in this case?

4

Re: ADI 2 Pro FS Overload/Short Detected

The merchant.

Regards
Matthias Carstens
RME

Re: ADI 2 Pro FS Overload/Short Detected

MC wrote:

The merchant.

Got it, thanks!

Re: ADI 2 Pro FS Overload/Short Detected

Hello,
I have the same problem here - with 3/4 phones and HD800s sennheiser headphones (Lo-power mode)
@LucidTurtle : did you replace the adi? Is the problem solved?
Thank you.
Best.

Re: ADI 2 Pro FS Overload/Short Detected

dctl wrote:

Hello,
I have the same problem here - with 3/4 phones and HD800s sennheiser headphones (Lo-power mode)
@LucidTurtle : did you replace the adi? Is the problem solved?
Thank you.
Best.


Hey,

Curious to find someone else in the exact same situation, but I'm happy to share my findings with you.

After making this thread and reading the replies, I sent my Adi in for repairs and got a new one. I've been using it for two months now, averaging about 6 hours of use every day on Hi-power mode with the HD800s connected. The unit has never once overheated, or short-circuted or anything. It works flawlessly and it gets way less hot than the previous unit did.
I can't say for sure that the problem won't occur again eventually, but the older device started exhibiting problems after using it for only one month so maybe it was just faulty.
But so far everything works just as it should.

8 (edited by dxmat 2019-07-10 09:48:27)

Re: ADI 2 Pro FS Overload/Short Detected

Same problem here.
I sent back my brand new ADI2 Pro FS as warranty.
Now I wait for a solution.

RayDAT, ADI-2 Pro FS R, UCX

Re: ADI 2 Pro FS Overload/Short Detected

Me too, only in summer in Rome. Probably the ADI is not climate change ready :-)

10

Re: ADI 2 Pro FS Overload/Short Detected

Could be a solution:
https://static.wixstatic.com/media/ea57 … _1534.jpeg

11 (edited by dxmat 2020-01-06 17:28:37)

Re: ADI 2 Pro FS Overload/Short Detected

Mine is back from assistance.
The motherboard has been replaced and now it works well.
The heat is always high. (my room temperature is now 28 ° C = 82.4° F)
I use a very silent fan by Noctua to keep the temperature more acceptable.

RayDAT, ADI-2 Pro FS R, UCX

Re: ADI 2 Pro FS Overload/Short Detected

I am getting the overload error message with my six-month old ADI-2 DAC.  In contrast to the problem described above, the problem with my ADI-2 DAC cropped up while the unit was still cold. 

Now, if I touch anything to the 1/4" jack (I've tried three pairs of headphones and a bare adapter), I get the error.  Powering down the unit, unlpugging, updating firmware, switching from high-power to low-power mode, and taking all other steps I could think of have not resolved the problem.

My kind and responsive dealer, Nice Cans of Austin, TX, is investigating what can be done...

https://lh3.googleusercontent.com/h2TUpixFNTBzG1H5g9F99hxopEpDy1IArnm3AVulALRws4LY6aGjxe4X0fqtzREvlfl23D5d4PQod24MmGPthw-rKYEPENvwvTq5_hcvtG_P-mOnSJ3ccscbYf22XCVF-4yER14PFDJYTOQ844tJ0vEGBBOJnB2vRvuXiAuEJfzokJT1yEI4Y4uBDdNy_runF70qgR0yzdXVrxOTyHXIoHQeaj8VY0FrWf8WfnOSYfY3i0-6GxftBX1ty3zw99gMjpYAf7GAvwIbieH7tB2rzhx1_nmsK7jOczoflPjLaNDosV7QLk5ZrSc1IrADWw6-FfTq2VLWnJhvk92XhtU1GsrQvvmvpgIQj7KxGSY_ibB2E9rEri5E0dd1WjwhIxQ409CPL_iQMDXEPoaT_N01D0VNOGdhPmOFYWxIvU7UHRzPRkDnkA37TGS_4F_tUE-fRtEAe53Z5WuGYX_RKVlT6YykwKS7zJi5de5VXE--w8LrgIWujLxX9eqGYNbEYrTEN1KuINy5D2eYdlTXe4F6csWxT_NBA-B680EUfJhCyCpHCqNSStLv8TcCDZqn1q4Q6lpC_lZEm3OUzQmZngAE_pBlayUmp22ogGH4uDIr4WB94vQVR-K-eQeV5ibgdY-3Rhk624Ey72Mq0JBo9iYbt4f4PGt6QYPFAPLe9hITTJdf8MNAatvDs3xUPzHx8ive3BBOOtKcWrMMq8xXkCOqZGiphBEXn9p37kMyHQPc23T5q8Fl=w1072-h804-no

Re: ADI 2 Pro FS Overload/Short Detected

Ah, I have the same problem now after a year, as the weather gets hotter. It’s now 28C here. I was using my 300ohm HD600 in low gain With volume at -30db. 2.5 hours later it displayed such message and the entire body is untouchable.

Is it because of a bad batch of components?

I will try 1/2 hp out tomorrow and see if problem presents there as well. As far as I remember it’s equally hot as 3/4.

14 (edited by KaiS 2020-06-19 21:45:54)

Re: ADI 2 Pro FS Overload/Short Detected

Had the same problem, appeared suddenly after I had ADI-2 Pro for a longer time.

Turned out that one of the 3 paralleled OPA1688 of one headphone amp's channel was broken.
Nothing that can be serviced DIY, the chip's thermal pad is really hard to solder.

So, this type of error makes the ADI-2 a candidate for factory service.

Re: ADI 2 Pro FS Overload/Short Detected

KaiS wrote:

Had the same problem, appeared suddenly after I had ADI-2 Pro for a longer time.

Turned out that one of the 3 paralleled OPA1688 of one headphone amp's channel was broken..


I doubt if that is the case. Yesterday HP 3/4 shutdown after 2~3 hours running at 28C ambient temperature. Today I tried HP 1/2 and after less than an hour of using at 27C room temperature. the unit display the overcurrent message and runs extremely hot. I almost never used HP 1/2 before, and having issues with both HP outs should be extremely rare...

Running low gain at -30db for 300Ohm headphone shouldn't stress the HP out that much.

16

Re: ADI 2 Pro FS Overload/Short Detected

KaiS is right. Send the unit in and it will be taken care of.

Regards
Matthias Carstens
RME

17 (edited by ning 2020-06-19 16:36:51)

Re: ADI 2 Pro FS Overload/Short Detected

MC wrote:

KaiS is right. Send the unit in and it will be taken care of.

Thank you MC. Just shipped my unit back to the dealer. You'll receive it soon.
oh btw, don't forgot the price https://forum.rme-audio.de/viewtopic.ph … 86#p154486!

Just curious,  is it because those opamps fighting each other which leads to shorter lifespan? (based on online picture I assume the outs are directly summed together without a resistor. the 47.0s seems to be feedback resistor?) No intention to criticize the design. Just want to learn more electronics knowledge.

18 (edited by KaiS 2021-04-15 10:16:25)

Re: ADI 2 Pro FS Overload/Short Detected

No, this "fighting" wouldn't work.
The 6x47Ω per channel are the summing resistors.

The 3 OPA1688 (= 6 amps total per side) are running as voltage follower at unity gain, feedback resistor = 0Ω.
There is an overall negative feedback loop (NFB) over the OPA1688 stack including the 6x47Ω's, bringing the final output impedance from 7.8Ω down to ~0.1Ω.

This way the 6x47Ω serve as load balancers, current limiters and to improve the linearity of the OPA1688.


If one of the OPA1688 channels breaks the "Overload/Short Detected" warning is triggered at relative low output level.

I hadn't investigated how the detection works, didn't need for my fix.


Further explanation on request:

The signal from the OPA1688 stack’s output goes back to the inverted input of the OP-amp that is driving the stack.

One would need to have a look at the basics of OP-amp circuit design to fully understand how that works.

The result is, the OPA1688 stack is “controlled” by another OP-amp configuration, which lowers output resistance, distortion and noise by the negative feedback factor, ca. 1:100 in this case.

Re: ADI 2 Pro FS Overload/Short Detected

Thank you KaiS, I learned a lot!

Re: ADI 2 Pro FS Overload/Short Detected

My ADI-2 Pro fs just started with the same issue. Mine is 3 years old. How can I get it fix?

21 (edited by ning 2022-05-02 07:26:25)

Re: ADI 2 Pro FS Overload/Short Detected

Unfortunately you need to send your device to your dealer (if in warranty) or RME (if not).

It's a 10 layer pcb and the output buffer has thermal pad soldered on board so no way to fix it. Motherboard replacement is required.

Re: ADI 2 Pro FS Overload/Short Detected

Hey Folks,

Do you have an idea of which op Amp is used before the 6 parrallel OP Amp stage?

https://drive.google.com/file/d/1rLkacT … p=drivesdk

Thanks in Advance

Re: ADI 2 Pro FS Overload/Short Detected

it's just a normal opa1602.
it's a pity that it's not configured as the master op amp in the nested feedback configuration. otherwise the noise will be even lower.

24 (edited by KaiS 2022-08-30 22:48:03)

Re: ADI 2 Pro FS Overload/Short Detected

ning wrote:

it's just a normal opa1602.
it's a pity that it's not configured as the master op amp in the nested feedback configuration. otherwise the noise will be even lower.

The 6 OPA1688 channels have their outputs and inverted inputs linked directly, running at a gain of “1”, and have a 47 Ohm output resistor each.
The headphone amp in total has a output impedance close to 0 Ohm.

This means, there must be an overall NFB loop through a “master OPA”.

I did not analyze this part of the schematic further when I replaced an OPA1688.

25 (edited by ning 2022-08-31 00:41:10)

Re: ADI 2 Pro FS Overload/Short Detected

KaiS wrote:
ning wrote:

it's just a normal opa1602.
it's a pity that it's not configured as the master op amp in the nested feedback configuration. otherwise the noise will be even lower.

The 6 OPA1688 channels have their outputs and inverted inputs linked directly, running at a gain of “1”, and have a 47 Ohm output resistor each.
The headphone amp in total has a output impedance close to 0 Ohm.

This means, there must be an overall NFB loop through a “master OPA”.

I did not analyze this part of the schematic further when I replaced an OPA1688.

the feedback path goes back to the first 1688 which is also driving the load (or put it in a fancy way, "feedforward").
Circuit is similar to the "Apheared 47 Headphone amplifier" (https://headwizememorial.wordpress.com/ … scrapbook/) in the DIY community long, long ago (2001).
RME didn't even change the resistor value (47ohm).
The master opa is also applied with a miller compensation to make the full circuit stable.

the above 1602 is just for gain adjust and lpf.

according to the datasheet, 1688 has higher noise than 1602, which makes the noise of the headphone amplifier higher.
Had the feedback path gone through the 1602, with no feedforward path, and the 6 1688s equally in parallel, RME could provide IEM out for Pro for free.

26 (edited by KaiS 2022-08-31 01:44:09)

Re: ADI 2 Pro FS Overload/Short Detected

ning wrote:
KaiS wrote:
ning wrote:

it's just a normal opa1602.
it's a pity that it's not configured as the master op amp in the nested feedback configuration. otherwise the noise will be even lower.

The 6 OPA1688 channels have their outputs and inverted inputs linked directly, running at a gain of “1”, and have a 47 Ohm output resistor each.
The headphone amp in total has a output impedance close to 0 Ohm.

This means, there must be an overall NFB loop through a “master OPA”.

I did not analyze this part of the schematic further when I replaced an OPA1688.

the feedback path goes back to the first 1688 which is also driving the load (or put it in a fancy way, "feedforward").
Circuit is similar to the "Apheared 47 Headphone amplifier" (https://headwizememorial.wordpress.com/ … scrapbook/) in the DIY community long, long ago (2001).
RME didn't even change the resistor value (47ohm).
The master opa is also applied with a miller compensation to make the full circuit stable.

the above 1602 is just for gain adjust and lpf.

according to the datasheet, 1688 has higher noise than 1602, which makes the noise of the headphone amplifier higher.
Had the feedback path gone through the 1602, with no feedforward path, and the 6 1688s equally in parallel, RME could provide IEM out for Pro for free.

Power amps, specially the fast ones, are always a question of stability with a large variety of loads.
More NFB loops - more stability problems.

The 47 Ohm is suggested in the 1688’s datasheet.

Interestingly, the topology of my 1st version ADI-2 Pro seems different, the 3 OPA1688 are all wired as voltage follower, with the non-inverting inputs tied together.
Or I haven’t recognized it, I wasn’t after that.

27 (edited by ning 2022-08-31 02:20:23)

Re: ADI 2 Pro FS Overload/Short Detected

> More NFB loops - more stability problems.

HP Amp stability issues caused by capacitive load are easy to solve and various compensation solutions are available.
Miller compensation used by ADI-2 is a good example.
Recent trend is to also incorporate solutions usually found in speaker amps.
transitional miller compensation, for instance, is now used in many HP amps and achieved good results(such as JDS, Topping, etc).

> The 47 Ohm is suggested in the 1688’s datasheet.

1688 datasheet does not use that. the buffer itself when using alone can drive headphone load stably without compensation such as additional output resistor.

> Interestingly, the topology of my 1st version ADI-2 Pro seems different, the 3 OPA1688 are all wired as voltage follower, with the non-inverting inputs tied together.Or I haven’t recognized it, I wasn’t after that.

based on the images posted by RME and Synthax,
https://synthax.jp/tl_files/images/products/adi-2pro/inside.jpg
The HP amp circuit hasn't been changed across the versions.

The 5 channels close to the headphone jack are in parallel.
The one channel far away from the jack is the master
it's also driving the load, but accepting feedback from the final output.
You can even see the 1K feedback resistor and compensation capacitor behind the first 1688 channel.
(on the picture, the feedback resistor is below the 6 pairs 47ohm resistors. the capacitor is located on left/right of the feedback resistor)

On the clearer image (https://i.postimg.cc/08P9Kk1j/V3.jpg) you can see pcb traces on the left hand side that the 1K feedback resistor connects the output of 6 paris of 47ohm resistors to the first 1688 channel.

28

Re: ADI 2 Pro FS Overload/Short Detected

ning wrote:

Circuit is similar to the "Apheared 47 Headphone amplifier" (https://headwizememorial.wordpress.com/ … scrapbook/) in the DIY community long, long ago (2001).

How old are you? I read about this configuration in 1993, in Burr-Browns App note AB-051. I remember headphone amp circuits that had 10 x 5532 parallel in that configuration.

ning wrote:

RME didn't even change the resistor value (47ohm).

Holy moses - you accuse me of having known and copied that circuit? Seriously?

Regards
Matthias Carstens
RME

29 (edited by ning 2022-08-31 06:25:44)

Re: ADI 2 Pro FS Overload/Short Detected

> How old are you? I read about this configuration in 1993, in Burr-Browns App note AB-051.

The AB-051 paper is linked in the "47 Headphone Amplifier" webpage discussed above as reference.
So I didn't think it would be necessary to link it here again.

> I remember headphone amp circuits that had 10 x 5532 parallel in that configuration.

douglas self published a power amp circuit using 37 x 5532 in parallel each channel.

> Holy moses - you accuse me of having known and copied that circuit? Seriously?

Calm down... Certainly not!

It's public domain knowledge that has existed for a long time.
perhaps 51ohm resistors are hard to find so people just grab whatever easily available, for instance, 47ohm....
the 47 HP Amp is listed above simply because it's widely known in the DIY community.
No offense at all.
As long as RME delivers good performance, using public knowledge should be encouraged.

All I wanna say in the initial post was, using the 1602 for error correction should in theory improve the noise performance.
KaiS deviated the topic to something different and I end up showing him the DIY 47 HP Amp to help him understand the topology in ADI-2.
I should have draw a ADI-2 HP Amp circuit diagram to avoid such confusion.

Re: ADI 2 Pro FS Overload/Short Detected

Does this overheating problem include PRO fs r be. Only pro and pro fs mentioned here. My unit gets awfully hot, but not hotter than described elsewhere in forum.

ADI-2 DAC, ADI-2 PRO, DigifaceUSB, UCXII, ARC, HEGEL.h80, KEF.ls50, HD650, ie400pro _,.\''/.,_

Re: ADI 2 Pro FS Overload/Short Detected

Spec is +5 - +50 C. 75% humidity. Maybe you shouldnt operate in a sauna, but a hot summerday without direct sunlight should be well whitin range.

ADI-2 DAC, ADI-2 PRO, DigifaceUSB, UCXII, ARC, HEGEL.h80, KEF.ls50, HD650, ie400pro _,.\''/.,_

Re: ADI 2 Pro FS Overload/Short Detected

ning wrote:

> More NFB loops - more stability problems.

HP Amp stability issues caused by capacitive load are easy to solve and various compensation solutions are available.
...
> The 47 Ohm is suggested in the 1688’s datasheet.

1688 datasheet does not use that. the buffer itself when using alone can drive headphone load stably without compensation such as additional output resistor.

From OPA1688 datasheet, to reduce overshot with capacitive load:


9.3.3 Capacitive Load and Stability

The dynamic characteristics of the OPA168x are optimized for commonly-used operating conditions. The combination of low closed-loop gain and high capacitive loads decreases the phase margin of the amplifier and may lead to gain peaking or oscillations. As a result, heavier capacitive loads must be isolated from the output.
The simplest way to achieve this isolation is to add a small resistor (for example, R OUT = 50 Ω) in series with the output.
...

33

Re: ADI 2 Pro FS Overload/Short Detected

ning wrote:

It's public domain knowledge that has existed for a long time.
perhaps 51ohm resistors are hard to find so people just grab whatever easily available, for instance, 47ohm....
the 47 HP Amp is listed above simply because it's widely known in the DIY community.

I have spent many hours to find the ideal resisiors for this circuit and the reasons they are in there. I could write an app note about it but won't. Whoever wants to know the background has to find it out himself.

Point is those resistors were neither copied nor just 'grabbed and put in there'. This kind of devaluating speculation is not helping.

Regards
Matthias Carstens
RME

Re: ADI 2 Pro FS Overload/Short Detected

Sorry, but just as an aside. I wonder why RME is kept from work with such unnecessary discussions, there are certainly more important things to do than to discuss something like this and in this way.

BR Ramses
UFX+, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1650v4, Win10Pro22H2, Cub12Pro

Re: ADI 2 Pro FS Overload/Short Detected

I don’t wanted to devaluate your efforts building a great high-power headphone amp that exceeds the quality of the DAC-chip in every regard, being overload protected by a unique circuit etc.

In contrary, I just wanted to point out that it’s not easy to do so, making an amp work stable on widely varying loads.

Re: ADI 2 Pro FS Overload/Short Detected

MC wrote:
ning wrote:

It's public domain knowledge that has existed for a long time.
perhaps 51ohm resistors are hard to find so people just grab whatever easily available, for instance, 47ohm....
the 47 HP Amp is listed above simply because it's widely known in the DIY community.

I have spent many hours to find the ideal resisiors for this circuit and the reasons they are in there. I could write an app note about it but won't. Whoever wants to know the background has to find it out himself.

Point is those resistors were neither copied nor just 'grabbed and put in there'. This kind of devaluating speculation is not helping.

Have you tried to move feedback path from the first 1688 to the 1602 that does gain control and differential->Single ended conversion? That IMHO is more important than resistor value selection.

Re: ADI 2 Pro FS Overload/Short Detected

Happy_amateur wrote:

Does this overheating problem include PRO fs r be. Only pro and pro fs mentioned here. My unit gets awfully hot, but not hotter than described elsewhere in forum.

Yours are probably fine.  An easy way to check is measure the wattage consumption. If it is over 12W when idle something must be fried. If it’s below 12W then it is normal.

38 (edited by KaiS 2022-09-01 12:41:19)

Re: ADI 2 Pro FS Overload/Short Detected

Happy_amateur wrote:

Does this overheating problem include PRO fs r be. Only pro and pro fs mentioned here. My unit gets awfully hot, but not hotter than described elsewhere in forum.

There‘s no overheating problem.

Don‘t worry, the protection circuit keeps track of the temperature.
If you don’t get the „Overload/Short detected...“-screen, nothing‘s wrong anyway.

If you get the screen, in almost all cases the message simply is what it says:
Real overload (too loud, quasi impossible with your headphones on your ears), a plug not all in, wrong or broken cable etc.


When idle, my ADI-2 already get‘s about ca. 15 °C above room temperature, on hot days this can feel hot to the touch, but is perfectly fine from the electronic’s point of view.

Re: ADI 2 Pro FS Overload/Short Detected

KaiS wrote:
Happy_amateur wrote:

Does this overheating problem include PRO fs r be. Only pro and pro fs mentioned here. My unit gets awfully hot, but not hotter than described elsewhere in forum.

There‘s no overheating problem.

Don‘t worry, the protection circuit keeps track of the temperature.
If you don’t get the „Overload/Short detected...“-screen, nothing‘s wrong anyway.

If you get the screen, in almost all cases the message simply is what it says:
Real overload (too loud, quasi impossible with your headphones on your ears), a plug not all in, wrong or broken cable etc.


When idle, my ADI-2 already get‘s about ca. 15 °C above room temperature, on hot days this can feel hot to the touch, but is perfectly fine from the electronic’s point of view.

I did some checking around and Im not worried. smile

That said its no secret that the ADI-2 PRO is a hot, small and crowded box. So its prob OK to be mindfull of ambient temps and air circulation. Not to put it on top of other hot equipment. No direct sunlight etc.

Generally this goes for all electronics

ADI-2 DAC, ADI-2 PRO, DigifaceUSB, UCXII, ARC, HEGEL.h80, KEF.ls50, HD650, ie400pro _,.\''/.,_