Short breaks in USB transmision

[jerryx4]

Hello,

 

I am using the Audionet ART G2 CD-player together with MAC Mini connected by means of a USB cable, using ART G2 as a DAC only. I am very satisfied with the effects, however, there seems to be one problem.

 

After turning the system on there are a few short (a fraction of a second, but audible) discontinuities/breaks of sound.

Those breaks are accompanied by the sound of the relay click inside of the ART, and they also occur even when no file is playing.

At the beginning the relay switching occurs every minute on average and becomes less frequent gradually.

 

There one thing I've noticed - when I check the voltage in the power strip, in the socket next to the socket where the Art is plugged in, the moment I touch the phase with the tip of the voltmeter, the relay switches. What is surprising, it switches even when I disconnect the metering wire from the voltmeter and put in in the phase hole in the same plug, the relay still switches.

 

The problem remains with another digital source - I used a Dell laptop and a MacBook Pro, both with power supply and working on battery only - and the problem is still there, even with battery only. However, with the battery, the problem seems to occur less frequently.

 

The Art G2 is connected through the EMI filter, the USB cable that I'm using is audio-dedicated.

 

Has any of you encountered a similar problem or can suggest a possible solution?

 

 

[wgscott]

Is the power strip grounded?

 

If not, that might be the source of the issue.

 

For diagnostic purposes, put a portable GFCI between the mains outlet and the power strip, and see what happens. If it trips, you have a serious problem.

 

[jerryx4]

Yes, the power strip and all devices are grounded.

 

I had the ground resistance checked by a professional company and it turned

out to be correct.

 

 

[wgscott]

This definitely wins the "most baffling question" award.

 

[One and a half]

inside the power strip with the unconnected meter probe, you are generating so much EMC that the ART trips...unlikely.

 

It's possible that disturbing the socket in the power strip with the meter probe is upsetting a mechanical connection in the power strip. If you start the CD player, the inrush current is higher causing heating/pitting effect on the weakened contacts in the power strip. Possibly this inrush keeps the heat on the contact long enough to cause an intermittent open, dropping lots of volts in the first few seconds (minutes) of play. (This is the player's de-thump or power supply startup relay). Since the player's power demand lowers during play, after a time, the contact cools & heals itself.

 

If you wanted to, you could put a power recorder or scope to look at the drop, but unless you're professionally trained working at anything above 24Vdc, I'm not going to tell you how this is done in this forum!

 

I would throw out the power strip and replace it. Power strips are made to a price, even the "expensive" ones.

 

The EMC filter consists of just a wire with toroids and caps to earth. Caps also add to the inrush but really wouldn't contribute to the contact heating in this scenario unless one of them is close to a short circuit.

 

[jerryx4]

that I only accidentally discovered that the breaks in sound can be caused by touching the socket with the meter probe (and it actually is only touching with the tip of the probe, not putting it inside). But this is not the cause of the problem since the problem itself started occurring before I checked the power strip.

 

The problem also occurs when the system has been left on for 24 hours and the USB transmission begins.

 

I've checked the system with and without the EMI filter - there was no difference.

 

But what I am sure about is that when I touch the power strip socket with the tip of the probe, there is a disconnection of sound / relay switch in the ART, or sometimes the ART even stops playing.

It happens even when I touch the phase connection in the power strip next to the one the ART is plugged in.