RobF Posted September 25, 2018 Share Posted September 25, 2018 (edited) So I am getting a humming noise from my speakers when I have my preamp connected to the rca inputs of my MC 275, but when I switch them out to XLR there is no longer a hum. The rca cables are new Blue Jeans. I tried to connect a cheaper rca cable I had laying around and the hum was even louder. I also removed and reinserted all the tubes. That same blue jeans RCA cable works just fine with no hum when hooked up to my MC 2205. One thing that did happen today was that the 275 suddenly turned off out of nowhere while I was playing music. Only now am I noticing this hum from the rca interconnects. Anybody know whats going on? Edited September 25, 2018 by RobF Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted September 25, 2018 Share Posted September 25, 2018 I use something like this for my subs over the past several years. It can also be used for a speaker. https://www.crutchfield.com/p_127SNI1/PAC-SNI-1.html?tp=61807 Quote Link to comment Share on other sites More sharing options...
RobF Posted September 25, 2018 Author Share Posted September 25, 2018 22 minutes ago, derrickdj1 said: I use something like this for my subs over the past several years. It can also be used for a speaker. https://www.crutchfield.com/p_127SNI1/PAC-SNI-1.html?tp=61807 Thanks derrick. So is this not a problem with the amplifier then and rather something normal with the MC275? Also to note, The humming noise goes away when I disconnect it from the preamp. Quote Link to comment Share on other sites More sharing options...
USNRET Posted September 25, 2018 Share Posted September 25, 2018 Do a search for ground loop. Quote Link to comment Share on other sites More sharing options...
MEH Synergy Posted September 25, 2018 Share Posted September 25, 2018 First things first plug all equipment into same outlet. Use a ground plug lifter ($2 from home depot). With a bit of patience and trying same outlet, different outlet, one ground lifted, both grounds lifted, you will find a magic combo (if there are no problems with your gear; it doesn't sound like it if cables solve the problem). I had a LARGE PA system. It was almost silent when I lived in one place. When I moved into another, CRAZY GROUND LOOP. Took me 2 hours, patience and less than $10 to solve the problem there.... Quote Link to comment Share on other sites More sharing options...
MEH Synergy Posted September 25, 2018 Share Posted September 25, 2018 It usually isn't very expensive if you are comfortable with wiring up your own electrical, to get a DEDICATED 30 amp outlet and split it into a dual duplex setup and then all current, noise and other problems will vanish. I highly advise that and you will notice a difference IMO. I'm sure others would be happy to say otherwise, but this has been my experience (even currently). Quote Link to comment Share on other sites More sharing options...
RobF Posted September 25, 2018 Author Share Posted September 25, 2018 (edited) Thanks for the replies. Given the layout of my home and space I have the amp connected to one outlet in the hallway and my preamp and turntables hooked up to another outlet in the dining room and my la scalas are placed in my living room 🙄. I got an extension cord and hooked up the amp to the same outlet as the other equipment and the hum is gone thanks Westcoastdrums. Next question is there any modifications I can make that will allow me to keep the amp hooked up to its own individual outlet away from the preamp and turntables and still get quality sound? Edited September 25, 2018 by RobF 1 Quote Link to comment Share on other sites More sharing options...
MEH Synergy Posted September 25, 2018 Share Posted September 25, 2018 Like I said, modify the outlet(isolated) . It is CHEAP. Tap into what you have available on your electrical box. Dedicated 20 amp is more than enough for most people. Buy a cheap used line conditioner. Problem solved. Sounds great. Audio advisor has a relatively affordable Pangea line. I always run amps and Preamp straight into the wall". Everything else goes into the same outlet isolated on the line conditioner so as to not interfere. Hope that helps. Quote Link to comment Share on other sites More sharing options...
RobF Posted September 25, 2018 Author Share Posted September 25, 2018 Helps a bunch thank you! Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted September 25, 2018 Share Posted September 25, 2018 You probably need isolation transformers on the RCA side. http://www.jensen-transformers.com/what-is-a-ground-loop/ Quote Link to comment Share on other sites More sharing options...
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