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mcamelo

HX Stomp - very noisy power supply?

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I get a lot of hum coming from the amp's speakers when I use my HX Stomp. Through careful elimination, I've found it to be caused by the Stomp's power supply.

 

I initially thought it was the Stomp itself but then noticed that it happens even with the unit turned off, as long as the power supply is connected.

 

As a matter of fact, simply bringing the cable (the one plugged to the amp) close to the power supply or its lead is enough to bring the hum back. They don't even need to touch and the power supply doesn't need to be connected to the stomp either.

 

As long as the power supply is plugged to the wall, bringing the cable near the power supply's unconnected plug is enough to cause the hum. Unfortunately the hum is also there when everything is connected and turned on. 

 

If I unplug the power supply from the wall, the hum stops. 

 

I cannot replicate the problem with any one of my other two power supplies (for pedals and a preamp, respectively).

 

Has anybody experienced anything similar? The Stomp stock supply can't be that noisy, can it? Maybe mine has got a problem? 

 

Any tips would be much appreciated. 

 

Thank you, 

Marcelo 

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Sounds like a classic ground loop where your power supply is on a circuit that has a differential in grounding with the circuit something else it's connected to (like an amp).  Get everything plugged into the same circuit or get a HumX for your power supply.

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All devices are connected to the same power strip. Forgot to add that bit. How could it be a ground loop it there is no physical contact between the two devices other than via the power strip? And isn't the stomp not grounded? Thanks for replying. 

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48 minutes ago, mcamelo said:

All devices are connected to the same power strip. Forgot to add that bit. How could it be a ground loop it there is no physical contact between the two devices other than via the power strip? And isn't the stomp not grounded? Thanks for replying. 

 

If everything is on a power strip it doesn't apply.  But in a ground loop situation ANY connection can cause the differential in ground to cause interference.  Your guitar connected to the Helix via a cord, the Helix connected to an amp via a cord or the computer via USB, etc.  Even your body can cause the ground differential to be balanced.  Just ask how many electric guitar playing singers have gotten the shock of their life when their lips touched a microphone.

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Here is a simplistic schematic of my setup. Amp and power supply connected to the same power strip. No HX Stomp involved. No other equipment connected to the strip or wall power socket. Guitar cable on one end connected to the amp and, on the other, simply hovering near the DC-3G power plug (without touching it). That's enough to cause the loud hum. If I plug the cable to a guitar, instead, I can play it with only minimal amount of buzz.

 

 

2BKOWQ.png

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The plot thickens!

 

Today I've discovered that if I plug my amp into the OUTPUT-RIGHT jack the noise/hum becomes close to negligible (somewhere in between the hum of a humbucker pickup and that of a single coil).

 

It does not make a difference which input jack I plug my guitar into, left or right.

 

I am using a completely empty preset (no blocks).

 

If I go back to the OUTPUT-LEFT jack, the hum is clearly audible (and annoying) even at practice volumes.

 

I've the tried Behringer Hum Destroyer and that helped a bit. It about halved the loud hum from the OUTPUT-LEFT jack. Interestingly, it has no discernible effect on the (quieter) hum I get from the OUTPUT-RIGHT jack. 

 

I've tried an AC filter and that made no difference whatsoever.

 

Although using OUTPUT-RIGHT is a good solution most of the time, I would like to use the Stomp on my stereo rig, so I am very keen to fix this issue. Could it possibly be a problem with my unit?

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Maybe also worth noting that the buzz is there  even before I turn the Stomp on (on the left output only). 

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Pretty shure the left output jack of your HX Stomp is not connected to ground. Accidentally stepped on the plug of a connected cable to the left output jack so it broke off?

 

If you have a multimeter at hand you can check whether it is defective:

Unplug everything from the HX Stomp. Only connect two cables: one to the left and one to the right output jack. Then measure the resistance between both sleeves, it should be 0 Ohms when ok and a high value when faulty.

 

Your power supply is not faulty. It just connects the amps ground with the HX Stomp ground with high impedance. You hear amplified mains hum.

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Thank you for the tip. Yes, the multimeter tells me that ground has been broken. But it gets worse, I've opened it to check for a possible broken wire and made the worst possible discovery: blown components:

PXL_20200923_113750830_MP.jpg

 

Would Line 6 service be able to repair something like this or will I have to get used to my mono HX Stomp. 

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I get noise from my stomp with high gain presets until i plug the usb in to my pc, can't really have my pc next to my pedals on stage. I may stomp my computer!

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On 9/23/2020 at 6:57 AM, mcamelo said:

But it gets worse, I've opened it to check for a possible broken wire and made the worst possible discovery: blown components:

 

I don't see that as a negative.... it's obvious! 

 

On 9/23/2020 at 6:57 AM, mcamelo said:

Would Line 6 service be able to repair something like this or will I have to get used to my mono HX Stomp. 

 

If it's just a few blown components it will be a very easy fix for an authorized service depot. Of course.... the real question is "what damage can't we see"? 

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