1 (edited by abtr 2019-02-10 14:03:13)

Topic: ADI-2 DAC USB input stopped working (again)

Well, this s*cks. sad 2 months ago I had the same problem and I sent back my unit for repair. Apparently the whole main board was replaced and the USB worked again. Today I changed the USB cable connecting a laptop to the ADI-2 DAC and when I plugged the cable into the ADI-2 I heard a low level tick through the speakers and the USB had stopped working again (the display says: USB disconnected).

I must have swapped USB cables hundreds of times in my setup with different USB DACs and DDCs and I never had a problem with any of them. Is this a known issue with some batch of ADI-2 main boards or am I the only one who encountered this (twice)? Note that USB should be save to disconnect and reconnect without first powering down the device..

2 (edited by ramses 2019-02-10 14:32:45)

Re: ADI-2 DAC USB input stopped working (again)

If this would be a general weakness of the ADI-2 DAC, then you would find more users here with the same issue, but this is not the case.

I remember that with Firewire 400 there was a danger of damaging the circuits when plugging in or out if the plug got twisted or something like that. You may experience a similar effect from a defective cable or USB port on your laptop.
I can't imagine that the ADI-2 DAC should be the problem, especially if it was freshly repaired. I'd rather guess a bad USB cable or a bad USB port on your laptop. At least I wouldn't rule that out.

Otherwise I fully agree with you, that plugging and unplugging USB devices should not cause any issues.

BR
Ramses
Win7 Prof, CubPro9.5, UFX+, XTC, ADI-2 Pro FS/DAC, RayDAT, ARC USB, Sonnet USB3-PRO-4PM-E

3 (edited by abtr 2019-02-10 23:06:05)

Re: ADI-2 DAC USB input stopped working (again)

If I'm the only ADI-2 DAC owner that blew the USB input of 2 units, then I agree that it seems unlikely that the ADI-2 is the problem. When the USB stopped working I used the USB 3.0 output port of a Lenovo laptop. It works fine with other USB DACs and DDCs and it has worked fine with the ADI-2. So I don't think it's faulty, but I will measure its 5V DC output. Could a defective USB  port produce a high voltage and/or current which damages some USB receivers (but not others)? If so, shouldn't there be some protective circuit to prevent this from happening? Considering a bad cable, I can only think of a short circuit, but could a short in a USB cable damage the receiver?

Another possibility is that when the USB input of the ADI-2 stopped working, I had some problems with the RME driver and I was swapping USB cables and connecting and disconnecting different PCs and an Intona to find out what the problem is. This is exactly what I was doing when I blew the first USB receiver two months ago. Could some buildup of static charge have caused this (twice)?

4

Re: ADI-2 DAC USB input stopped working (again)

While mostly known from FireWire, static electricity and very different ground levels between two USB devices can also damage the USB receiver chip. Every USB unit (should) has a protective circuit to prevent that - these are standard components build for exactly that application.

In case a dangerous voltage occurs the protective component can short that voltage and thus protect the USB receiver. It now depends on the amount of voltage and the power (time) of higher voltage if a) the dangerous voltage is just collapsing and that's it, b) the protective component is destroyed, c) protective component and USB receiver are destroyed.

In your case it seems that you have a very high floating voltage on your notebook, which is shorted to ground over the ADI and the units connected to its analog outputs. You should make sure the laptop is properly grounded, same with your monitors/amps. And maybe get someone with a voltage meter to check the current situation.

It also seems when you don't change the setup the next ADI will die soon...

Regards
Matthias Carstens
RME

5 (edited by abtr 2019-02-11 22:13:02)

Re: ADI-2 DAC USB input stopped working (again)

MC wrote:

While mostly known from FireWire, static electricity and very different ground levels between two USB devices can also damage the USB receiver chip. Every USB unit (should) has a protective circuit to prevent that - these are standard components build for exactly that application.

In case a dangerous voltage occurs the protective component can short that voltage and thus protect the USB receiver. It now depends on the amount of voltage and the power (time) of higher voltage if a) the dangerous voltage is just collapsing and that's it, b) the protective component is destroyed, c) protective component and USB receiver are destroyed.

In your case it seems that you have a very high floating voltage on your notebook, which is shorted to ground over the ADI and the units connected to its analog outputs. You should make sure the laptop is properly grounded, same with your monitors/amps. And maybe get someone with a voltage meter to check the current situation.

It also seems when you don't change the setup the next ADI will die soon...

Thanks! I checked and the voltage difference between the USB ground of the Lenovo laptop (pin 4) and the ground of my audio system was 59V! The laptop uses a 2 prong SMPS (wallwart) without a ground connection. I grounded it with a wire that connects the negative output of the SMPS (usually the outer jacket of the power plug) to mains ground. Now the voltage difference is exactly 0.000 smile

OK, mystery solved. But the ADI-2 DAC seems to be more susceptible to this problem than average. My other DACs survived the Lenovo USB output thus far. So who is to blame, Lenovo or RME? Anyway, it's a good heads-up for checking this with each computer I connect to my audio system!

Oh, and I use a (grounded) linear 12V DC power supply for the ADI-2; not the standard wallwart..

6

Re: ADI-2 DAC USB input stopped working (again)

So there is the reason it broke two times. The ADI's power supply is ungrounded/floating, thus no problem plugging it into your ungrounded notebook...

Regards
Matthias Carstens
RME

Re: ADI-2 DAC USB input stopped working (again)

I'm sorry about what happened to your device. But am I reading this right? You bought one of these allegedly better (audiophile) power supplies for the ADI and at the end damaged the ADI-2 DAC with it ?

BR
Ramses
Win7 Prof, CubPro9.5, UFX+, XTC, ADI-2 Pro FS/DAC, RayDAT, ARC USB, Sonnet USB3-PRO-4PM-E

Re: ADI-2 DAC USB input stopped working (again)

ramses wrote:

I'm sorry about what happened to your device. But am I reading this right? You bought one of these allegedly better (audiophile) power supplies for the ADI and at the end damaged the ADI-2 DAC with it ?

I think that's what Matthias suggests. But nothing in the manual implies that you shouldn't use a grounded power supply. In fact, it states on page 10: "the choice of power supply is not critical." Moreover, with the floating standard SMPS the ADI-2 is still grounded via the connected power amp and the voltage difference between the floating USB ground of the laptop and the ADI-2 USB remains a whopping 59V. So I don't see how my linear power supply is the problem..

9 (edited by abtr 2019-02-12 22:47:51)

Re: ADI-2 DAC USB input stopped working (again)

MC wrote:

So there is the reason it broke two times. The ADI's power supply is ungrounded/floating, thus no problem plugging it into your ungrounded notebook...

I use a well regulated so called linear power supply for all my (USB) DACs and it is quite common among audiophiles to do so. The idea is that a SMPS may be well regulated and suppress line noise, but it also throws back HF noise and LF leakage current into the mains which ends up in other audio components.

Anyway, could you elaborate on why you think my non-floating LPS broke the ADI-2 USB? As said, both with the LPS and with the standard SMPS the potential between the USB grounds of the Lenovo and the ADI-2 is 59 Volts which seems to be the problem. Thnx.

Oh, and I use a low capacitance mains isolation transformer to separate the DAC and amps from SMPSs and other noisy devices that may be plugged into the mains power.

10

Re: ADI-2 DAC USB input stopped working (again)

I can't proove that. It is just a thought. Yours broke two times in that setup, thousands of others never have a problem. As I said the real cause of the issue is unclear. Thinking that ground here and there must be the same might be right for audio, but not for static sparks and such stuff.

The rest of what you said is correct and it is good to see a user who  knows what he is doing, and optimizes his setup on a factual base instead of hearsay and believe.

Regards
Matthias Carstens
RME

Re: ADI-2 DAC USB input stopped working (again)

Last October I had the same problem with my ADI-2 Pro and, on 2018-10-23 15:47:12, I started the topic "Lost USB connectivity." Topic remained unnoticed for a while but eventually MC noticed it and recommended to unplug the unit power supply and any analog connections when plugging and unplugging USB cable  to/from my other piece of equipment (a streamer/renderer) suspect of causing the problem. At that time there was no discussion of solution by fixing voltage/ground issues. I have been following MC's advice when connecting USB cable to the replacement unit I got from the US Distributor--unbelievable quick response and service from them, by the way!!

dr.larkos

12 (edited by abtr 2019-02-15 22:17:26)

Re: ADI-2 DAC USB input stopped working (again)

MC wrote:

I can't proove that. It is just a thought. Yours broke two times in that setup, thousands of others never have a problem. As I said the real cause of the issue is unclear. Thinking that ground here and there must be the same might be right for audio, but not for static sparks and such stuff.

The rest of what you said is correct and it is good to see a user who  knows what he is doing, and optimizes his setup on a factual base instead of hearsay and believe.

I may have found the culprit in my setup. My mains isolation transformer is a balanced toroid type that doesn't like mains DC-offset. So I installed a (Rod Elliott) DC-blocker on the (single phase) AC input of the transformer. But the mains ground must still be connected to the secondary center tap of the transformer, which is the 'new' ground for the powered equipment. In my home/system this introduced a DC voltage which audibly messed with the balanced zero or null. So I installed a capacitor (18μF 400V MKP) in the mains ground connection to the balanced center tap. This completely solved the audible DC problem but it introduced another; the capacitor may get charged enough to kill a ADI-2 USB chip.

Without this series capacitor, the mains ground connection introduces at least 5mV DC-offset/skew into the balanced output. To remedy any future static discharges into USB receivers, I bridged the capacitor with a 25KOhm resistor. Now the DC component of the balanced ground is around 0.01mV and I think it sounds even better. smile

The question remains why the ADI-2 died and my other DACs survived in the same setup. I did use the Intona isolator most of the time. When I blew the ADI-2 USB I connected it directly to an ungrounded laptop..

13 (edited by dr.larkos Yesterday 17:24:20)

Re: ADI-2 DAC USB input stopped working (again)

abtr, the Intona galvanic isolator (that you mention) was not in use during any of the two instances when you blew the ADI-2 USB port, right?

I am asking because I am trying to ascertain if the Intona is a worthwhile acquisition.

Thanks,
dr.larkos

14

Re: ADI-2 DAC USB input stopped working (again)

Correct. With the Intona in the USB chain this could not have happened because it galvanically/electrically isolates USB ground and signal connections. I use the non-industrial version (up to 1000V protection) which is cheaper.

Re: ADI-2 DAC USB input stopped working (again)

Thanks, abtr.