Noise from USB DAC....Earthing Issues......

[nickthechef]

Hi all,

Got another question for you all.
I have a USB DAC (CambAudio DAC Magic100) between my PC and my pre-amp.

I have a high pitched wine/noise coming from the PC (no surprise). When the PC is disconnect the interference goes.

Is there a way to isolate the DAC from the noise from the PC that would not interfere with a 24bit data rate.

[RichB]

http://hifimediy.com/usb-isolator

this should do the trick

[roob]

The DM100 has an earth lift switch on the back panel for usb hum issues, have you tried changing its position to see if that sorts it?

[nickthechef]

The DM100 has an earth lift switch on the back panel for usb hum issues, have you tried changing its position to see if that sorts it?

Hi Andy,

Already have that set to lift, it's worse when in the normal position.
Have had to resort to using a 16bit optical out. No noise there, but not much use for 24bit audio files etc.

[nickthechef]

http://hifimediy.com/usb-isolator

this should do the trick

Seen that as well - not good for 192KHz 24 bit. Max support for 96KHz.
Thanks though

[roob]

Drastic solution get rid of that crappy PC and treat yourself to a Mac:D
Never had any issues using Macs with a variety of usb dacs.

[RichB]

Is it a desktop pc you're using or a laptop.

Laptop psu vary in quality and are often rubbish. A decent Kensington psu can make a world of difference.

[roob]

You could try one of those iFi micro usb power supplies
http://www.amazon.co.uk/iFi-Micro-iUSB-Power-Supply/dp/B00AU07NZA
or a AQVOX
http://www.aqvox.de/usb-power_en.html

[struth]

Is it a desktop pc you're using or a laptop.

Laptop psu vary in quality and are often rubbish. A decent Kensington psu can make a world of difference.

I've got 2 Kensingtn psu's for lappy use and are excellent value

[nickthechef]

I've got 2 Kensingtn psu's for lappy use and are excellent value

Hi,

Well have managed to sort out a fix.
Basically I had a small Intel NUC PC as my digital music source. It is also plugged into the network via Ethernet and and the tv via hdmi and an external drive.
There was, for some reason, some noise on the +5v USB line coming from the PC to the DAC. This noise was either coming from the PC PSU or the tv.

The work around I came up with was to some how isolate the DAC from the noisy PC PSU, or wherever it was coming from.
I got hold of a small USB hub that could take it own external power supply and plugged the DAC in to that. Then I modified the the usb cable running from the hub to the PC by making a small incision in to the cable a cutting the ground and the +5v lines. Transmit and Receive were left intact.

Using a small clean power supply to power the USB hub the +5v line is restored but this time completely isolated from the PC.

Hey presto no more noise. Result!

[struth]

nice work Nick. ingeneous.

[Jankoff]

You could try one of those iFi micro usb power supplies
http://www.amazon.co.uk/iFi-Micro-iUSB-Power-Supply/dp/B00AU07NZA
or a AQVOX
http://www.aqvox.de/usb-power_en.html
Learned today about the Aqvox. Wonder if the iFi given here would bring about a serious improvement over the Aqvox. The idea is to use a Aqvox or a iFi to power up the USB of the old notebook + the hiface evo one trio (given below) I am using to feed my main (hi-endish) setup. Might also try it it with the Asynch-1 I am using with my home PC. Any advice about the possible difference between the Aqvox and the iFi? Thanks in in advance!

[Ammonite Audio]

I'm still very impressed with the Intona USB isolator, which is compatible with 24/196. See http://theartofsound.net/forum/showthread.php?43103-Intona-USB-Isolator

[Jankoff]

I'm still very impressed with the Intona USB isolator, which is compatible with 24/196. See http://theartofsound.net/forum/showthread.php?43103-Intona-USB-Isolator

Very interesting! Another German gadget. Now I am asking myself - if to obtain higher SQ one can add such a filter, don't they actually incorporate filters in those USB interfaces that we know for sure are good? If they do, why have a good USB interface and pay more for a filter?
My experience is the following. I have the HiFace Evo One trio (given below) with a rather old notebook as a source. The signal from the HiFace Evo One interface goes into a valve DAC (costing €1000, additionally upgraded with very good valves), then follows a good analogue section. All cabling and connectors, including 240V ones, are first-class (when DIY, soldering is always WBT Silver Solder or better - it matters a lot!), the mains socket is Furutech platinum, the whole system and each and every component rest on various anti-vibration devices. When the HiFace Evo One trio replaces the transport, costing another €1000, it puts it to shame. I got the HiFace Evo One trio itself for the same price, approximately €1000, but this proved to be a much better investment than the €1000 for the transport.
As to the notebook USB output. Surely, it is not good electrically. But the question is: if SQ is so good now, is it not due to the Evo Power Supply? To put it in another way: doesn't the Evo Power Supply do the same job as Aqvox/iFi? And won't the possible inclusion of Aqvox/iFi filter the current ADDITIONALLY and bring about more SQ?
I was in contact with Mr. Manunta, the designer and owner of M2Tech. I did not ask him this question. And if I do, will he answer? Designers have secrets, and have the right to secrets. But he told me that using an old notebook as a source for the HiFace Evo One trio was perfectly OK. So?
Well, if I go ahead and buy a filter and it adds nothing to SQ, I will find a place for it somewhere else, e.g. with the Asynch-1. But what if Stan, too, has designed and implemented good filtering in the Asynch-1? This €100 or €250 device will add nothing to the quality. It will be a sheer loss of money.
I will add here that I am extremely satisfied with the Asynch-1 and that I am using it with a PC that has a motherboard (Gigabyte G1.Sniper A88X) with a so-called DAC-up USB port: "Featuring a gold plated USB 2.0 port, GIGABYTE USB DAC-UP provides clean, noise-free power delivery to your Digital-to-Analog Converter. DACs can be sensitive to fluctuations in power from the other USB ports, which is why GIGABYTE USB DAC-UP takes advantage of an isolated power source that minimizes potential fluctuations and ensures the best audio experience possible" (quote from the Gigabyte Internet site). So, is my satisfaction entirely due to Stan's work? Or does this special USB port contribute? If yes, how much? I may have an answer to this question soon, when I test the second Asynch-1 (that I got from Stan a couple of days ago) on another PC, without a special USB output.
Of course, being an incurable audiophile, I will never give up tweaking and wasting money ("given life and health", as we say in my language). The only unknown is where exactly it will go. :D :D :D

[Ammonite Audio]

I have not read too deeply into the Intona design, but I believe that its aim is to provide total electrical isolation between USB devices, rather than apply any filtering. Intona did not design it for audio, it seems. Does it turn a relatively cheap laptop source into the equivalent of an expensively specced bespoke audio PC, with SOtM PCIe USB card? Well, that's an experiment that I intend to conduct in due course - I hope that the laptop/Intona does come out as equal, because the combination is a whole lot cheaper and more convenient than a dedicated PC. In the meantime, I find myself listening rather more to music via the computer, so on that basis I'm happy.