Noise in balanced outputs - Parasound - diyAudio
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Old 30th April 2012, 10:07 PM   #1
dalgard is offline dalgard  Denmark
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Default Noise in balanced outputs - Parasound

Since this is about a Parasound I've asked John Curl, but all he could tell me was that it "appears to be a system problem". Can anyone tell me, what he means by that?

Can anyone help me solve my problem? I need the balanced outputs to drive some ICEpower modules in bridged mode.

Thanks!

Quote:
I've recently bought a Parasound Halo C2 via Audiogon and the balanced outputs have a lot of noise - interference from the DSP, FM radio and so on! The RCA outputs are absolutely silent and noise-free. When I touch the cabinet and a radiator I get more voltage than should be expected.

Do you have any idea what's going on?

I would be extremely (!) thankful for some kind of assessment. Parasound support is kind of uninterested and doesn't seem to really have a clue.


P.S. The noise is very obvious and characteristic in these respects:

- There's a medium-high freq hum which changes pitch with different DSP settings, e.g. digital vs. balanced analog input
- I can hear FM radio and general background noise
- The noise level doesn't vary with volume
- It somewhat goes away when DSP is bypassed or the unit is muted
- It is ONLY present when using balanced out, not when using RCA

I have systematically changed all the variables in the system and everything points towards the balanced output being adversely affected by noise from the DSP and other ambient sources. It would have to take place just before it actually becomes balanced but after it is split away from the unbalanced output.

It would appear that either the balanced circuit is broken or it has lost some kind of isolation??
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Old 1st May 2012, 09:59 AM   #2
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Please check the safety earth continuity from the mains plug to the preamp chassis and also those of the equipments you are interconnecting to .......you shouldnt feel ANY voltage between case and a radiator ...
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Old 2nd May 2012, 02:47 AM   #3
Simon B is offline Simon B  United Kingdom
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Quote:
Originally Posted by dalgard View Post
.....When I touch the cabinet and a radiator I get more voltage than should be expected......




Something seriously wrong here. Either in your sound setup or your house wiring. I don't want to be alarmist, but it could kill you, or someone else. Dead.

Do check the safety earths as epicyclic suggests. If you can't find an obvious problem that you are competent to fix, please seek professional assistance immediately.



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Old 2nd May 2012, 04:02 AM   #4
kevinkr is offline kevinkr  United States
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Make sure the balanced connectors are wired correctly and that pins are not swapped! I believe the Parasound uses true balanced outputs, but there are a few products with pseudo balanced outputs - aka unbalanced over XLR.
What are you doing with pin 1?

See the section on 3 pin audio here: XLR connector - Wikipedia, the free encyclopedia

Make sure that the grounding/safety issue is resolved, and the ICE power module inputs are wired correctly. I believe they also need to be earth grounded for safety.
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Old 20th April 2014, 08:18 PM   #5
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How did you contact John Curl? I need a contact to sort out my Parasound also...
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Old 21st April 2014, 09:09 AM   #6
dalgard is offline dalgard  Denmark
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I ended up getting the problem fixed by the importer here in Denmark which is also a repair shop (Lydbutikken ).

Apparently, when they opened the cabinet and turned it on, the transformer burned off, so they were kind enough to replace it for me. I believe the problem was gone after that.
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