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Isolating Digital Noise, need help.

I'm hearing noise from my ARC CDP thru my speakers presenting as a high frequency "whine" or "soft screeching." I need to isolate my digital from the AC line it shares with my analogue components. Running another dedicated line is not an option at this time.

I was wondering if a power strip with isolated receptacles, such as star-grounding, would be an alternative to a separate AC line.
As a test, I now have the CDP connected to a different outlet in my house and the noise thru my system is eliminated.

Would this type of power strip be an effective solution, and if so, I could use some recommendations. I have several layers of Blue Circle power conditioning, so I would need a strip with surge/EMF/RFI protection.
128x128lowrider57
ptss
1,964 posts
 
Have you tried a cheater plug on your digital-without changing anything else?
lowrider57's avatar
lowrider57 OP
5,417 posts
 
ptss,
yes, using cheater plug on the Audience cable from ARC CD will get noise.
jea48
4,425 posts
 


jea, I hope that's a rhetorical question, because I'm going by what I read in the Whitlock paper.
Ralph thinks my Sunfire amp may have an atypical grounding design.

No, I did not mean it as rhetorical question at all.

(I assume the ICs are not long.)


I understand the principle of ground-loop in this case because they are connected by an unbalanced line.

Not that I doubt you read it. Where did you find that in the white paper? We are not talking about noise.

  
https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

I think Ralph is probably right about the Sunfire grounding design and somehow that is causing a difference of potential, voltage, to exist between the two safety equipment grounded chassis. Thus current flow, 60Hz ground loop hum.

Just curious what happens if the ground cheater is placed on the amp and not on the preamp? Did you ever try it that way?  

When you find your multi meter I would also be curious to know, if from the IEC male ground contact pin on the Surfire amp if there is any measureable resistance  from the IEC ground pin to the metal chassis of the Amp. There should not be any resistance. The meter should read short. (Disconnect the ICs from the preamp when do the test. Shouldn't make any difference but it totally isolates the amp from anything else.) 

lowrider57's avatar
lowrider57 OP
5,417 posts
 
@jea48,
First, thank you for the tip on checking continuity of the two cables. They both test with a beep using the Continuity Setting.
Using the Resistance setting, both test close to zero.

As far as my understanding of ground loop, when two devices are plugged into mains power (both grounded), then connected together by an unbalanced cable, there will be current running thru that cable to each component. Is this correct?
BTW, the section on audio ground-loops in the Whitlock paper starts on page 56.
lowrider57's avatar
lowrider57 OP
5,417 posts
 
jea, I didn't try the cheater on the amp. I didn't think it was a good idea to lift the ground since it is a high power/current amp.

I will test the resistance on the Sunfire tomorrow, good idea. FYI, this amp was built in 1998 and has a fixed 3-prong AC cable. The next generation amp included an IEC cable.
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