Mac Mini 2012 via Decible to NAD M51 - High pitch noise!

[autyharley]

Setup

Source:

Mac Mini i7 2.6ghz 2012

Decible 1.2.8 and Amarra 2.4.1

 

Dac:

Via USB (old printer cable - new one in the post to try as I don't think this will cause this)

Nad M51.

 

Amps:

Rotel RHA-10

Rotel RHB-10x2 Bi-amped

 

Music:

96khz/24 bit flacs, 192khz/24 flacs, and standard rips.

 

Problem:

 

Playback at 96khz/24 bit is perfect but when I play or set the output to anything above, 176khz or 192khz I get a high pitch tone constantly in the back ground. It does not change with volume, just the frequency increasing. I am think it may also be there at 96khz but very quiet.

 

My thoughts are that it could be a earthing issue?

Doubt it would be cable interference? or poor quality of cable as it is from an old printer.

Would it be safe in thinking that changing the frequency output, can alter the sound level of a earth loops noise??????

 

I tried different software, Amarra was hopeless at managing the outputs, but both made not difference to the "digital noise/earth hum???"

 

Anyone had similar issues?

Cheers Harley

[iago]

I tried different software, Amarra was hopeless at managing the outputs, but both made not difference to the "digital noise/earth hum???"

 

Anyone had similar issues?

Cheers Harley

 

If it is a faint 'screeching' noise (not unlike the noise modems used to make over the phone wire) that varies with processor load, it might be crossfeed from the computer. I had the same issue with a monitor containing internal speakers connected to the desktop computer. I had to lift the monitor's ground to mitigate the problem.

 

Try to use a shorter USB cable (printer cables are normally longish) and put all devices' power connectors as closely together as possible on the power strip. If your power outlet is symmetric, and you have not already phase-aligned your plugs, try reversing (turn 180 degrees) the power connector of the computer. Check if your noise varies with CPU load by playing silence and stressing the computer (normally moving the mouse and opening / closing / moving a few windows should suffice). If it does not change, the noise might have a different cause.

[mav52]

Setup

Source:

Mac Mini i7 2.6ghz 2012

Decible 1.2.8 and Amarra 2.4.1

 

Dac:

Via USB (old printer cable - new one in the post to try as I don't think this will cause this)

Nad M51.

 

Amps:

Rotel RHA-10

Rotel RHB-10x2 Bi-amped

 

Music:

96khz/24 bit flacs, 192khz/24 flacs, and standard rips.

 

Problem:

 

Playback at 96khz/24 bit is perfect but when I play or set the output to anything above, 176khz or 192khz I get a high pitch tone constantly in the back ground. It does not change with volume, just the frequency increasing. I am think it may also be there at 96khz but very quiet.

 

My thoughts are that it could be a earthing issue?

Doubt it would be cable interference? or poor quality of cable as it is from an old printer.

Would it be safe in thinking that changing the frequency output, can alter the sound level of a earth loops noise??????

 

I tried different software, Amarra was hopeless at managing the outputs, but both made not difference to the "digital noise/earth hum???"

 

Anyone had similar issues?

Cheers Harley

 

It looks like from the picture that you have some connection from the Mini to the Yamaha AVR

 

Also I would clean up your cable runs, as it looks like you have power cables, signalling cables crossing in all sort of directions

 

Have you tired the M51 directly to your amp since the M51 can be used as a pre

[autyharley]

If it is a faint 'screeching' noise (not unlike the noise modems used to make over the phone wire) that varies with processor load, it might be crossfeed from the computer. I had the same issue with a monitor containing internal speakers connected to the desktop computer. I had to lift the monitor's ground to mitigate the problem.

 

Cheers for the reply! I wouldn't describe it as like a modem noise but more like the old transformers on laptops and cellphones that used to produce a high pitch noise, much like the noise you may get with a minor ear infection....One thing i did notice under load was a pop on the rear right speaker via my amp when connected multi channel. It seams to be when I load the USB hdd external...so I think maybe a build up is happening there?

(Try to use a shorter USB cable (printer cables are normally longish) and put all devices' power connectors as closely together as possible on the power strip. If your power outlet is symmetric, and you have not already phase-aligned your plugs, try reversing (turn 180 degrees) the power connector of the computer. Check if your noise varies with CPU load by playing silence and stressing the computer (normally moving the mouse and opening / closing / moving a few windows should suffice). If it does not change, the noise might have a different cause.

 

I will definitely try these too! In my photo the setup is very messy as I am in the process of building and Elm unit for it all with four shelves. So I have it all over the place to measure the cable lengths and distances required for the shelves. I hope to have them finished this or maybe next week depending on how much I get done on my day off. All this info will help and I will let you know how I go! Thanks for that!

[autyharley]

It looks like from the picture that you have some connection from the Mini to the Yamaha AVR

 

Also I would clean up your cable runs, as it looks like you have power cables, signalling cables crossing in all sort of directions

 

Have you tired the M51 directly to your amp since the M51 can be used as a pre

 

As per the other post, totally agree with the mess of the cables but this is intentional at the moment as I am building an elm unit for it all. It is connected the the Yamaha via HDMI video, optical audio, then it is also connected via Coax 6 via router as well as having an external hdd (which i think maybe the problem) with an ac power connector. At the moment I am talking to some people to build me a customised power grid but not getting very far.

 

The NAD would be great but only 1 set of outputs, need two to run both amps.

 

Whats your thoughts on the external hdd?? It spins loud and you can hear it through the speakers. Also when testing loads it was werse when I was using the ext hdd.

Cheers

[autyharley]

Right I have reset up my whole kit, cables sorted, external hdd removed. But I have not rotated the power cable. But now with some testing I can say that the tone is constant and there in the background the whole time for 192khz 172khz. 96khz is algood as well as all below.

 

Has anyone had a similar problem that they have resolved?

I will reverse the polarity of the power connector too.

[mav52]

Right I have reset up my whole kit, cables sorted, external hdd removed. But I have not rotated the power cable. But now with some testing I can say that the tone is constant and there in the background the whole time for 192khz 172khz. 96khz is algood as well as all below.

 

Has anyone had a similar problem that they have resolved?

I will reverse the polarity of the power connector too. [ATTACH=CONFIG]3138[/ATTACH]

very clean looking... Before I would start reversing polarity get your multi meter and check the connections... not saying the problem is noted but during their test the author had to make a few changes. NAD M51 Direct Digital D/A converter Measurements | Stereophile.com

[avta]

If you have not yet done so try putting all connections into the same power strip. You may be dealing with ground loop noise and this is one way to avoid it.

[autyharley]

If you have not yet done so try putting all connections into the same power strip. You may be dealing with ground loop noise and this is one way to avoid it.

 

Yeah I have done that, unfortunately I think it maybe coming from the mini! Plugged in my Colorfly via coax and had no trouble, but struggling to find some 192/24 wav files to really test it.

[autyharley]

very clean looking... Before I would start reversing polarity get your multi meter and check the connections... not saying the problem is noted but during their test the author had to make a few changes. NAD M51 Direct Digital D/A converter Measurements | Stereophile.com

 

Cheers, I have printed it off and will have a good read of this!

[edpadden]

I have resolved this issue. Internally, I ran a wire from the ground screw over by the power inlet and soldered it to the RCA's ground. This completely removed the high pitch noise I was also hearing.