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  #16  
Old 06-30-2022, 06:42 PM
phcorrigan phcorrigan is offline
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Originally Posted by jonfields45 View Post
I take it you don't test 9 volt batteries by tasting them :~)!
Typically not, but in any case there's not enough current to kill you. Probably not enough current from most external power supplies either, but I tend to err on the side of caution.
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  #17  
Old 07-01-2022, 09:19 AM
necrome necrome is offline
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The place I live at uses UK plugs so I'll try figure something similar out, thanks again for letting me know how to go about it!
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  #18  
Old 07-01-2022, 04:40 PM
phcorrigan phcorrigan is offline
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Originally Posted by necrome View Post
The place I live at uses UK plugs so I'll try figure something similar out, thanks again for letting me know how to go about it!
My understanding is that grounding on UK electrical systems is pretty much the same as on U.S. systems. That is, the neutral side of the circuit and the ground (earth) are bonded together at the building's main electrical panel.

Everything that has been said here about ground loops should, AFAIK, apply to UK and European electrical systems. I would suspect that basic circuit polarity testers and ground loop hum eliminators are available there as well.

A little about ground loops, which are a specific cause of hum (60Hz in the US and Canada, 50Hz in the UK and Europe). Current should only flow on the "hot" and "neutral" lines, not on the ground or earth line. When current is flowing on the ground it is usually the result of an issue with the wiring itself or some other device on the circuit causing current to flow on the ground. The best solution to the problem of ground loops is to fix whatever is causing the problem. A ground loop hum eliminator is the next best thing, and likely the only thing you can do when plugging in to an electrical system that is not yours.

If you can't find one to buy, or don't want to spend the money, this article will show you how to build one, with instructions for both 120V and 240V electrical systems:

https://circuitcellar.com/resources/...-ground-loops/

I built one like this and it is mounted inside my amplifier case.

I hope this helps.
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2012 Martin HD-28V
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2018 Gretsch G5420TG
Oscar Schmidt Autoharp, unknown vintage
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  #19  
Old 07-02-2022, 08:08 PM
jonfields45 jonfields45 is offline
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While I don't think I can eliminate a ground loop, I think his problem is more likely common mode noise between two devices each using their own switching power supply.

When he takes the AC33 off batteries and onto its wall power adapter, he is making it solidly grounded which exposes the PC's much more powerful common mode noise.

The right solution is a DI between the AC33 and PC. The cheap solution might be floating the wall adapter's ground to the AC33. However it is only a cheap experiment and no guarantee.
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  #20  
Old 07-02-2022, 10:10 PM
phcorrigan phcorrigan is offline
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Quote:
Originally Posted by jonfields45 View Post
While I don't think I can eliminate a ground loop, I think his problem is more likely common mode noise between two devices each using their own switching power supply.

When he takes the AC33 off batteries and onto its wall power adapter, he is making it solidly grounded which exposes the PC's much more powerful common mode noise.

The right solution is a DI between the AC33 and PC. The cheap solution might be floating the wall adapter's ground to the AC33. However it is only a cheap experiment and no guarantee.
I had a noise issue trying to use an A/B switch to switch headphones between my PC and mixer. I used something similar to this:

https://www.amazon.com/Xinsany-Compa...%2C131&sr=8-76

I built mine using a component that had two isolation transformers on a PC board, but I suspect this device works in a similar fashion. Unfortunately I can't find a link to the component I used.
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2012 Martin HD-28V
1984 Martin Shenandoah D-2832
2018 Gretsch G5420TG
Oscar Schmidt Autoharp, unknown vintage
ToneDexter
Bugera V22 Infinium
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  #21  
Old 07-03-2022, 01:51 PM
phcorrigan phcorrigan is offline
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Quote:
Originally Posted by phcorrigan View Post
I had a noise issue trying to use an A/B switch to switch headphones between my PC and mixer. I used something similar to this:

https://www.amazon.com/Xinsany-Compa...%2C131&sr=8-76

I built mine using a component that had two isolation transformers on a PC board, but I suspect this device works in a similar fashion. Unfortunately I can't find a link to the component I used.
Here's the component I used, along with two jacks and a plastic box:

https://www.ebay.com/itm/402539446545?hash=item5db9388111:gCgAAOSwbYJfpsb s&amdata=enc%3AAQAHAAAA4Mv3Jr7nsfVuImdiq3BYmoc9nKu kmlp%2FJNreVcKoMZUSMuJyHJOVAFHrmBMkRJJxRTyKCO0saW6 i39GcOr2SHGU2BWoss%2FrsrsRo0u%2B%2BwgdW1p35KHJHpeP %2BVeHzR14vqsxSy6YvN4Jli1J2oWdvnL24%2FSTOSt3HVs2rN 7f8FUTRNVoIbHfueX%2FYhjLgw%2FguKF%2BJifXuweDbQKeA8 9L1CEOBalOiCMYqzRPAwYmxHDK3WagtJfzViKZXZQm3xezPpK8 ymUwnSFnwq33GBuv2xhGRbVy5lmypuH8e3NvoIO1z%7Ctkp%3A BFBM-JbN2bhg

A similar item is available on Ali Express.
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Patrick

2012 Martin HD-28V
1984 Martin Shenandoah D-2832
2018 Gretsch G5420TG
Oscar Schmidt Autoharp, unknown vintage
ToneDexter
Bugera V22 Infinium
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