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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => Installed Sound/Contracting FUD Forum Archive => Topic started by: john manson on October 31, 2005, 04:57:58 pm

Title: noisy coffee machine
Post by: john manson on October 31, 2005, 04:57:58 pm
Hi guys, Im hoping someone has a cure for a noise issue I've come across.

I got called out last week to a new bar with a new sound system. The company who did the installation has since tipped over, so I don't know much about the wiring. Anyway the problem is every time the coffee/espresso machine starts porring (ie: the motor starts) it makes a loud click/thump through the PA. Im unsure if they are on the same power so I ran an extention from another fuse but it still made the same noise. I then went through and isolated each unit to find the it only made this clicking/thump noise when the cd player is plugged into the rest of the system via a line mixer. I then tried a transformer between the cd-player and the mixer, this did quieten it down somewhat at the start but now ( a week) later seems louder than before.

Is this a power issue or maybe EMF(sp?) ? Any suggestions would be great.

Thanks in advance
John
Title: Re: noisy coffee machine
Post by: Hal Bissinger/COMSYSTEC on October 31, 2005, 10:22:00 pm
I'm going to assume that the CD player is with and derives its power with the rest of the audio equipment from the same receptacle. What kind of transformer are you talking about? Power isolation (what kind?) or in the audio lines?

How close is the coffee machine to the CD player? If it is EMI moving the CD player temporarily will change it's effect.

I'm much more inclined to believe that this is a power or ground problem even though you did try powering the coffee maker with an extension cord from another circuit. That circuit could still be on the same phase. You mention fuses, that's a little scary. I hope you meant circuit breakers. Even so there could be problems with the panel or the way the circuits were run.

So if the coffee machine is close to the audio system move one of them and see what happens. If nothing then investigate the power.

-Hal
Title: Re: noisy coffee machine
Post by: john manson on October 31, 2005, 10:43:48 pm
Thanks for the reply. And yes it was a line level transformer. I'll try moving the cd player and see what happens. I just thought it strange that if only effected the cd player and not the amps.

I'll let you know how I get on with moving it.

John