Noise coming through speaker changes when plugged into the wall

[johnah5]

Hi I did a search and could not find what I was looking for. I don't understand how this happens so any help appreciated.
System is tube power amplifier and Grimm MU2 player and Devore O/96 10ohm speakers.

Amp and Grimm plugged directly into wall generic power cord = least noise heard from tweeter of speaker
amp and Grimm plugged directly into wall with Audioquest power cord = audible hum
amp and Grimm plugged into panamax power strip/protector = less audible hum but more than directly into the wall.

confused as to how the audioquest power cord would cause a significant hum and why the panamax power strip would cause a hum?

Any thoughts greatly appreciated
jh

 

[sergeauckland]

To me the answer is obvious:- Throw away the branded power cords and power strip and use sensible generic items.

As to why it happens, that would need technical investigation, but I would suspect poor grounding and/or leakage from any filtering.

S

 

[johnah5]

Ha exactly what I did. The least noise is generic copper power cords directly into the wall but I am curious as to why this is happening. I saw Amir's review of the Niagara 1200 which he concluded doesn't do anything to improve the mains so how can these cords/power strip cause the noise to be audible via speaker. jh

 

[Timcognito]

Run an extension cord from another room (kitchen is almost always on another circuit) and re-test. Problem could be in the home, old dimmers and lighting can create havoc.

 

[johnah5]

Tim there is not a problem unless I use the audioquest power cord or plug into the panamax power strip. Directly into the wall is almost silent. Question is why/how does a power cord or power strip create noise coming out of the tweeter?
jh

 

[DVDdoug]

It's most likely related to grounding. Sometimes a ground loop (multiple ground paths) can create a problem and sometimes the lack of a ground can cause a problem.

These problems aren't that common but they can be very difficult to solve.

Typically you get 50/60Hz hum (or related harmonics) but that shouldn't be coming out of the tweeter. The Grimm might have a (higher frequency) switching power supply that's the source of the noise but it also seems to be ground-related. You might try your computer or phone (or TV) instead of the Grimm to see if it goes-away. Or just unplug the Grimm from the amplifier.

 

[Holmz]

Noise or hum?

 

[Speedskater]

Manufactured AC power cords with problems are known to happen.
Defects:
1] Swapped wires.
2] Missing or not connected Safety Ground/Protective Earth wire.
3] Poorly crimped wire strands.
4] Poorly machined contacts.

 

[johnah5]

Noise or hum?

it is a buzz or hum out of the tweeter. I am not sure what the diff is between a noise or a hum. The question is why is it louder when I have the upgraded cord in or when I use the power strip? It is near silent when I plug into the wall. thanks

 

[Holmz]

it is a buzz or hum out of the tweeter. I am not sure what the diff is between a noise or a hum. The question is why is it louder when I have the upgraded cord in or when I use the power strip? It is near silent when I plug into the wall. thanks

If you can capture the sound or describe it, then we can maybe tell you why.

But if it is coming out of the tweeter, then it is not likely to be a 60 or 120 Hz hum.

 

[johnah5]

yes always coming out of the tweeter. it is a constant noise that gets quite audible with the upgraded power cord. So odd that a power cord could cause noise to be audible out of the tweeter. When directly plugged into the wall with no other devices in the outlet you have to place your ear near the tweeter to hear anything. JH

 

[johnah5]

Manufactured AC power cords with problems are known to happen.
Defects:
1] Swapped wires.
2] Missing or not connected Safety Ground/Protective Earth wire.
3] Poorly crimped wire strands.
4] Poorly machined contacts.

Thanks these are high end cables and this is happening on three diff cables so unlikely it is one of the above reasons. The generic cable is not causing this noise. JH

 

[Timcognito]

Do some tests with just the amp and just the Grimm

 

[vddobrev]

Have you checked the phase (the lead wire) if you are in Europe, rotate the schucko plug and see if it helps. Is the plug IEC C13? It has labeled L N and Ground, check to see if it is plugged correctly. Also, I wouldn't call AudioQuest an upgraded wire. Just see for yourself, it has no certificate markings, like UL etc. and has no technical specs, just marketing writing... Just saying, sometimes an expensive cable may be worse, or simply defective.

 

[johnah5]

In US. So to restate the question why would high end cables and/or a power strip cause audible noise out of the tweeter in the speaker?
Using generic cable into the wall socket with nothing else in that socket I get almost zero noise from the tweeter. If I just swap one power cord I get audible noise out of the tweeter. If I just add in the power strip get noise out of the tweeter. Running an EL34 tube amp push/pull and Grimm MU2. Thanks

 

[vddobrev]

In US. So to restate the question why would high end cables and/or a power strip cause audible noise out of the tweeter in the speaker?
Using generic cable into the wall socket with nothing else in that socket I get almost zero noise from the tweeter. If I just swap one power cord I get audible noise out of the tweeter. If I just add in the power strip get noise out of the tweeter. Running an EL34 tube amp push/pull and Grimm MU2. Thanks

Possible causes:
1. Defective power cable, even if it is high end. It could be its shield (I am assuming it is shilded) is not connected properly internally (it should only be connected to N or Ground on the source end, i.e. the power plug at the receptacle), or the L/N could be crossed internally by manufacturing error.
2. Surge protection circuitry in the power strip (if any) could be causing it
Can't think of anything else. As long as I know, in the US the power plug is coded, you can't insert it the oposite way.

Edit: Is there a difference between the power plug of the generic cable and the power strip and AudioQuest cable? Is any of them 3 prong and others 2 prong? I lived in the USA in the past, and I know there are 2 or 3 pin power plugs, where one is the ground....

 

[johnah5]

Possible causes:
1. Defective power cable, even if it is high end. It could be its shield (I am assuming it is shilded) is not connected properly internally (it should only be connected to N on the source end, i.e. the power plug at the receptacle), or the L/N could be crossed internally by manufacturing error.
2. Surge protection circuitry in the power strip (if any) could be causing it
Can't think of anything else. As long as I know, in the US the power plug is coded, you can't insert it the oposite way.

thanks can there be a ground issue with the power cord that interacts with the tube amp? There are three brand new power cords I am testing so I doubt all three have a problem but they are all causing the same noise. Very strange indeed. jh

 

[vddobrev]

thanks can there be a ground issue with the power cord that interacts with the tube amp? There are three brand new power cords I am testing so I doubt all three have a problem but they are all causing the same noise. Very strange indeed. jh

Check my post edit. Can you show picture of the 3 new cables, the power plugs, and the generic one. Ground issue most likely.

 

[Holmz]

Check my post edit. Can you show picture of the 3 new cables, the power plugs, and the generic one. Ground issue most likely.

Why do you say that?

 

[alex-z]

System is tube power amplifier and Grimm MU2 player and Devore O/96 10ohm speakers.

confused as to how the audioquest power cord would cause a significant hum and why the panamax power strip would cause a hum?

This problem potentially has 2-3 parts.

1. Power cables and speaker cables are effective broadband antennas, a lot of "audiophile" brands actually pickup more RF noise than generic OFC or CCA cables.

2. A lot of audio companies producing power strips and conditioners have poor design. For example, star grounding creates equal impedance along each path but is highly susceptible to RF noise pickup. I have never had an issue with high quality units like a Tripp Lite Isobar6Ultra.

3. Your DAC/amp are expected to reject this RF noise, but some models do this poorly and there is often negative quality/price correlation. Try a combo with known good performance, such as a Fosi Z3D + Hypex NC252MP.