scottyk
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Jan 25, 2011

Hum when I plug my T1 into a in-house PA

Hi, We've been regularly using our L1 Model II with T1 Tonematch no problem at a number of venues. Recently we've started playing at a small bar with a quality Martin Audio in-house PA. There I use the T1 with separate external power supply, and run the Master out from the T1 to the XLR input of the bar. Unfortunately I get a massive hum as soon as I plug into the XLR port of their PA system. I've tried everything imaginable, switching cables, power points, isolators etc. Nothing works.

However if I power the T1 from the separate base stand of my L1 Model II (ethernet to ethernet cable) the majority of hum disappears. It seems by using the T1 as a standalone mixer with separate power supply I am creating some sort of major hum and I've no idea why.

Would really appreciate any help on this. I've seen other musicians plug in standard mixers to the same bar inputs and never have any of these problems. Thanks, Scott.
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Eric-at-Bose
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May 20, 2020

Re: Hum when I plug my T1 into a in-house PA

Dear Scottyk,

Thank you for the question! It sounds like you are creating whats called a "ground loop". You are hearing the 60hz hum from the AC power line being used in the club. This can usually happen when the audio system that you are plugging into is using a different circuit than your mixer. There is no one best answer as to how to deal with this. Please refer to an excellent resource on our L1 wikipedia page here: http://toonz.ca/bose/wiki/index.php?title=Ground_Loop

That link should provide you some possible things to try to get the hum within manageable terms. As always, feel free to contact us directly at 877-335-2673 for further assistance!

Thank you and have a great day,

Eric-at-Bose
scottyk
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Jan 25, 2011

Re: Hum when I plug my T1 into a in-house PA

Okay thanks Eric, think I've tried most of these options but am going to re-test every possible alternative tomorrow. Cheers from NZ!


quote:
Originally posted by Eric-at-Bose:
Dear Scottyk,

Thank you for the question! It sounds like you are creating whats called a "ground loop". You are hearing the 60hz hum from the AC power line being used in the club. This can usually happen when the audio system that you are plugging into is using a different circuit than your mixer. There is no one best answer as to how to deal with this. Please refer to an excellent resource on our L1 wikipedia page here: http://toonz.ca/bose/wiki/index.php?title=Ground_Loop

That link should provide you some possible things to try to get the hum within manageable terms. As always, feel free to contact us directly at 877-335-2673 for further assistance!

Thank you and have a great day,

Eric-at-Bose