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Microserver noise being picked up by DAC


Edward
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Grateful for any help here please?

 

Yesterday I spent some hours trying to diagnose (and then fix) an issue I have with a Microserver. Basically my USB DAC is picking up constant hiss from the Microserver.

 

The miscroserver is doing HTPC (more specifically audio) duties. Configured minimally: one HDD, Windows 7 and JRiver Media Centre with audio out via USB DAC (Musiland Monitor 01) Streaming files from a different Microserver over Ethernet.

 

The hiss is present even if the Microserver has no drive, no memory, no HDMI card, nothing connected, and everything conceivable switched off in BIOS (e.g. ethernet).

 

The same hiss is present with another Microserver I have and indeed another HP machine (old Pavilion). However the hiss is not present when I use it on a spare notebook (Compaq).

 

I only became aware of this constant hiss when I changed over to a new amp. I guess the hiss was always there but my previous amp was not so sensitive.

 

Any ideas?  I simply have run out of ideas as to what I can try next.

 

Unfortunately I don't have a spare DAC and am loathe to buy a spare just to discover the hiss is still there. I'd rather build a new HTPC

 

I beginning to think that the HP is simply very noisy (poor quality control) as compared to say the Compaq I tried. But then again there must be thousands of people who use a Microserver as an audio device.

 

cheers

Edward

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Hi schoondoggy,

 

Wow that is such a fast response, it was only minutes ago when I posted. :)

 

Yes it is a USB powered DAC and yes indeed I tried the front and back USB ports (all of them) I also disabled the front ports, tried on the back ones and vice versa. No joy.

 

I did think the USB power may be the hiss, however the hiss is not there when I use the same DAC on a different machine (the compaq). In fact I initially thought there was something wrong with the Compaq as I heard absolutely nothing from the speakers ( I was a few inches away), until I played a track. In fact playing via the Compaq really showed how well everything was (sadly I can't use the compaq permanently, for example as no HDMI etc).

 

regards

Edward

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thanks again,  I will see if I can pick up a (low profile) USB card on the way home from work.

 

I tried the USB DAC in a HP Pavilion desktop, same problem of hiss.

 

Maybe portables are shielded better?

 

I would love not having to throw away the Microserver.

 

Edward

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Laptops are all DC power, the AC to DC conversion takes place in the power brick, so some of the noise is isolated.

Can the DAC be powered by a power supply? 

Some have had to go to USB Isolators to clean things up;

https://www.google.com/search?q=usb+isolator&oq=usb+is&aqs=chrome.2.69i57j0l5.7228j0j4&sourceid=chrome&espv=210&es_sm=122&ie=UTF-8

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Ah yes, good point about the external power brick.

 

Your useful thoughts has got me putting my thinking cap on again. Maybe an external USB hub with its own power supply will do the trick.  I'm pretty sure I have one lying around, so i will try that. If that does not work (or a USB card) then I will look at an USB isolator as you suggest. I'm in the UK so will need to research local sources.

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update:

 

externally powered usb hub is no good. Simply picks up the existing noise generated by the Microserver (presumably noise from the internal PSU).

 

I will look at USB isolator or a ground loop isolator.

 

Alternatively I wonder if I get an external power supply of some sort and retrofit it to the Microserver. Maybe something like a pico psu?

 

E

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update:

 

externally powered usb hub is no good. Simply picks up the existing noise generated by the Microserver (presumably noise from the internal PSU).

 

I will look at USB isolator or a ground loop isolator.

 

Alternatively I wonder if I get an external power supply of some sort and retrofit it to the Microserver. Maybe something like a pico psu?

 

E

PICO supply you ask....and we deliver....http://homeservershow.com/forums/index.php?/topic/6955-installing-picopsu-in-microserver-gen8-including-power-usage/

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