or Connect
Head-Fi.org › Forums › Equipment Forums › Computer Audio › USB DAC Suspected Ground Loop Issue
New Posts  All Forums:Forum Nav:

USB DAC Suspected Ground Loop Issue - Page 2

post #16 of 25
Quote:
Originally Posted by One and a half View Post
 

The butcher guitarist, idea of the shield is to keep the noise out, there;s still a lousy grounding system happening on his AC lines

 

Hello One and a half!

 

I was reading up on the Ifi USB and the grounding option ISOEarth seems like just what I need.

 

My question is, should I buy the iFi or should I get the Russ Andrews PSU for the irDAC to eliminate the ground loop?

post #17 of 25
Quote:
Originally Posted by Bloodflowerz View Post
 

 

Hello One and a half!

 

I was reading up on the Ifi USB and the grounding option ISOEarth seems like just what I need.

 

My question is, should I buy the iFi or should I get the Russ Andrews PSU for the irDAC to eliminate the ground loop?

Now that's a good question. I would have more faith with the ifi and you can use it for other DACs you purchase in the future. Many people have used the ifi with a lot of success, I bought one, but it didn't do anything for noise reduction, so this is really a system, especially the AC side dependent. The Russ Andrews supply is good only for the irDac and any other DAC that has that input connector and power requirement.

 

Both solutions "isolate" the break between the AC power and the USB signal, so the objective is reached either way. The Russ Andrews would be providing cleaner DC to the DAC, so the analog to your amplifier would improve also and this has to be taken into account as important. Buy both?

post #18 of 25

Hi,

 

Once I received my Emotiva Mini Amp, to complete this chain, Computer > Dac > Amp > headphones, my expectations of sound quality wasn't as high as I hoped.  After reading around looking for potential diy improvements I ended up cutting the 5v and Gnd wires on the Usb cable.

 

Cutting the 5v is supposed to help clean up the signal somewhat as it's coming from a noisy computer, and it did help - more on that later, however, I found after cutting the ground wire there was a sine wave noise leaking through the headphones, similar to ground loop noise, but didn't fluctuate at all, just one leveled beep.  I tried switching between all usb ports, to no avail and tried lots of different combinations which didn't work.  I wanted to find a way to remove the noise without having to patch the wires back up again. Cutting both wires in the Usb cable yielded improvements to the sound quality.

 

With both wires cut on the Usb, I found plugging my active studio monitors into the same outlet and turning them on made the sine wave noise disappear, how odd!, Leaving them switched off didn't help at all, they had to be plugged in and turned on. Not ideal if i'm going to be listening to my headphones for the remainder of the night.

 

In the end, I got fed up of leaving the speakers on just to clear up the sine wave noise.  One thing is certainly clear, cutting the 5v and Gnd on the Usb made a huge difference in sound quality,  I had done blind tests back and forth. But with the Gnd and 5v not sitting in the middle this sine wave noise was there, still intruding and obviously having an impact on the sound.

 

I found even though I disconnected both ground and 5v of the Usb cable as to Isolate the Dac from the Computer, I had not truly stopped all unwanted noise/distortion from travelling from the computer through the cable to the Dac, there was only two data wires connected! How can this be?

 

I started to fiddle with the Usb connection at the back, low and behold, with a slight tug as to not pull the wire completely out, the sine wave noise had gone!

 

My immediate thought was, once I try listening to some music the sound is going to be messed up, missing a channel or something, lol, nope, sound was clear as day, and my god it sounded much better than before, and before that. 

 

I can't believe a £400 dac, async Usb n all, has been affected by the lack of galvanic isolation in such a huge way.  To describe the difference would be easy.. Each sound has its own natural characteristic and is supposed have its own space so you can identify where it is, create a perfect picture, right? Well, out the box, using Usb, My M1 Dac couldn't provide an accurate detailed analogue reproduction of each sound, music was slightly blurry, lacked natural binding across the spectrum.  Yes, at first I thought the sound was fab, or so I thought.  

 

Now I have some sort of galvanic isolation working (Usb slightly pulled out), i'm shocked at how good everything sounds, especially 24/96 material, I didn't know my He-500 headphones could sound this good. I was missing out on detail, and now there is lots of it, lots of attack, energy and great synergy.  Something the M1 dac is supposedly renowned for, but I never knew until just recently! 

 

I blame the computer.

 

Just to clarify its not my imagination, If I plug that Usb cable all the way into the Usb port, the sine wave noise instantly reappears, of course, as mentioned above patching up the ground and 5v wires would eliminate the noise too yet defaults to mediocre quality. 

 

I've been reading up on my motherboard, and found many have run into noise leakage issues with x58 chipset motherboards, something to do with cpu vaoltage leakage?? - I've tried disabling settings in the bios, to no avail. 

 

For the time being my work is done.   Will be looking into testing a Usb Isolator out in the near future so the Usb cable isn't half hanging out. 

 

Update : My apologies for the amount of edits. Impulse writer. 


Edited by fluidz - 11/17/13 at 7:43pm
post #19 of 25
Quote:
Originally Posted by fluidz View Post
 

Hi,

 

Once I received my Emotiva Mini Amp, to complete this chain, Computer > Dac > Amp > headphones, my expectations of sound quality wasn't as high as I hoped.  After reading around looking for potential diy improvements I ended up cutting the 5v and Gnd wires on the Usb cable.

 

Cutting the 5v is supposed to help clean up the signal somewhat as it's coming from a noisy computer, and it did help - more on that later, however, I found after cutting the ground wire there was a sine wave noise leaking through the headphones, similar to ground loop noise, but didn't fluctuate at all, just one leveled beep.  I tried switching between all usb ports, to no avail and tried lots of different combinations which didn't work.  I wanted to find a way to remove the noise without having to patch the wires back up again. Cutting both wires in the Usb cable yielded improvements to the sound quality.

 

With both wires cut on the Usb, I found plugging my active studio monitors into the same outlet and turning them on made the sine wave noise disappear, how odd!, Leaving them switched off didn't help at all, they had to be plugged in and turned on. Not ideal if i'm going to be listening to my headphones for the remainder of the night.

 

In the end, I got fed up of leaving the speakers on just to clear up the sine wave noise.  One thing is certainly clear, cutting the 5v and Gnd on the Usb made a huge difference in sound quality,  I had done blind tests back and forth. But with the Gnd and 5v not sitting in the middle this sine wave noise was there, still intruding and obviously having an impact on the sound.

 

I found even though I disconnected both ground and 5v of the Usb cable as to Isolate the Dac from the Computer, I had not truly stopped all unwanted noise/distortion from travelling from the computer through the cable to the Dac, there was only two data wires connected! How can this be?

 

I started to fiddle with the Usb connection at the back, low and behold, with a slight tug as to not pull the wire completely out, the sine wave noise had gone!

 

My immediate thought was, once I try listening to some music the sound is going to be messed up, missing a channel or something, lol, nope, sound was clear as day, and my god it sounded much better than before, and before that. 

 

I can't believe a £400 dac, async Usb n all, has been affected by the lack of galvanic isolation in such a huge way.  To describe the difference would be easy.. Each sound has its own natural characteristic and is supposed have its own space so you can identify where it is, create a perfect picture, right? Well, out the box, using Usb, My M1 Dac couldn't provide an accurate detailed analogue reproduction of each sound, music was slightly blurry, lacked natural binding across the spectrum.  Yes, at first I thought the sound was fab, or so I thought.  

 

Now I have some sort of galvanic isolation working (Usb slightly pulled out), i'm shocked at how good everything sounds, especially 24/96 material, I didn't know my He-500 headphones could sound this good. I was missing out on detail, and now there is lots of it, lots of attack, energy and great synergy.  Something the M1 dac is supposedly renowned for, but I never knew until just recently! 

 

I blame the computer.

 

 

You could use one of these

 

Try another USB cable, this time don't cut the cables, but pull out enough to make the noise go away. Is it the same effect? Also not sure what you mean by a sine wave noise, is it hum or hash?

post #20 of 25

This isolator works wonder for less than 30$/22€. At least as long as you pass 16bits/44.1khz audio, since isolators based on adum4160 chips don't have enough bandwidth for high-res.

post #21 of 25
Quote:
Originally Posted by One and a half View Post

You could use one of these

Try another USB cable, this time don't cut the cables, but pull out enough to make the noise go away. Is it the same effect? Also not sure what you mean by a sine wave noise, is it hum or hash?

Ringing sound. Like beeeeeeeep.

Let me be clear here, using an untouched Usb cable causes no ringing noise to begin with, so I cant pull it out enough to eliminate the ringing if it doesn't exist.
The ringing sound only appears when I cut the GND wire on the Usb cable.

Having just slept for 8 hours, fresh ears, I've just switched back and forth again with my modded usb cable, 5v and gnd cut, slightly tugged out, flawless quality!
A/B tests between the two usb cables, massive difference!

The only issue here is every now and then my Dac like to handshake with the computer, Jriver fails to initialize the device, so I need to reboot (standby button pressed twice) the M1 Dac and all is working again.

With my M1dac, when I pull the usb cable slightly out of the computers usb, i hear a couple of high pitch beeps. If music is playing, momentarily I loose sound, so I reboot the Dac, sound returns, and the ringing noise has gone too.

Apparently tugging the usb cable out half way is supposed to cut the data lines on the usb cable, leaving the power intact, for some unknown reason its the other way round here!

Thanks
Edited by fluidz - 11/18/13 at 7:25am
post #22 of 25
Quote:
Originally Posted by 00940 View Post

This isolator works wonder for less than 30$/22€. At least as long as you pass 16bits/44.1khz audio, since isolators based on adum4160 chips don't have enough bandwidth for high-res.

I'm finding myself listening to 24/96 Pink Floyd more often than not, I don't think that usb 1.1 cable will suffice.

Thanks.
post #23 of 25

Another thing..

 

Instead of pulling the usb cable slightly out, if I plug in my active monitors to the same outlet, and turn them on, the ringing is lowered greatly and can only be heard if I squeeze my open headphones against my head to isolate any background noise.

 

To put things into perspective. Bear in mind the ringing noise is only caused by the Gnd being cut, cutting the 5v makes no difference here.

 

Usb cable - Gnd cut - studio monitors not plugged in the wall, ringing noise.

Usb cable - Gnd cut - studio monitors plugged in the wall and turned on, ringing noise is lowered and can hardly be heard.

Usb cable - Gnd cut - studio monitors not plugged in the wall/plugged in at the wall, usb cable slightly tugged out, ringing noise disappears completely.

 

It may very well be that I have a faulty psu/motherboard, bad grounding in my house - countless possibilities for the diminished quality to begin with but at least I've found a solution. I think I'll try using my sisters laptop and install Jriver, unplugged at the wall, and see if that yields the same result without tinkering with the usb cable. 

 

Using a usb isolator will probably just do the same thing, but the sound will be travelling through a foreign circuit, god knows what will be happening to the signature. 

 

Before purchasing a new amp for the headphones and external dac, I already had issues with my Yamaha hs80m speakers.  When plugged directly into a Titanium HD internal sound card I heard the effects of ground loop, the noise leaking into my speakers was crazy and the only solution was to use an isolation transformer between the speakers and computer. 

 

There must be a lot of noise travelling around my computer causing voltage fluctuations, and having an impact on the quality of sound produced by my Dac. I can see why these isolators exist. Why haven't all usb dacs got them built in to begin with? To make money selling expensive isolators perhaps? 

 

I just tried listening to music via jriver using optical, and my god it sounds congested in comparison to what I've achieved here.  


Edited by fluidz - 11/18/13 at 8:12am
post #24 of 25
Quote:
Using a usb isolator will probably just do the same thing, but the sound will be travelling through a foreign circuit, god knows what will be happening to the signature. 

Isn't the sound in digital format when it is in your usb cable? 

 

Thus it would make no difference sound wise to have usb isolator between computer and the DAC.

post #25 of 25
Quote:
Originally Posted by Headzone View Post
 

Isn't the sound in digital format when it is in your usb cable? 

 

Thus it would make no difference sound wise to have usb isolator between computer and the DAC.

The USB digital signal is a string of (hopefully) square waveforms of 5V amplitude plus noise residing on the 0V and the peak of the waveform. This is an analog waveform, it's a voltage, no mystical digital signal! See also : Audiostream Industry voice Parts 1 and 2

 

The DAC's USB Differential circuits, the A & B lines, only work on the difference between the two compared to the 0V line, like an XLR, ignore the noise, so that's how the digital circuits in the DAC work, and much of the rest of the computer.

The noise levels are still there and couple to the analog output stages via the 0V and or an earth from the mains power supply. This noise is the clarity hit that Fluidz reports. Noise tries to find its way back to the source (the computer), but has found an easier path to annoy in the DAC circuits. 

 

The isolators work (example : iFi USB), since filtration is attempted over mainly the RF bandwidth and to lift the shield of the USB cable. A popular method is to divorce the +5V from the computer, and create a fresh clean 5V supply (Example: AQVOX). The 5V is used only to handshake with the DAC to start to lock on to the A&B signals, or use that power for the USB input stage, it depends on the DAC design how the 5V is used. Some DACs totally ignore the 5V.

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Computer Audio
Head-Fi.org › Forums › Equipment Forums › Computer Audio › USB DAC Suspected Ground Loop Issue