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Humming?

Hello, I have a Music Hall MMF5.1 going into a Creek OBH-18 phono pre-amp. The thing is, I have a very audible humming noise coming out of my speakers. I am pretty sure it's my turntable to pre-amp connection as as soon as I disconnect the power supply to the turntable, the humming disapears. I have a grounding wire connected from the turntable to the pre-amp, and if I move the grounding wire around, the humming varies in intensity (from almost gone to loud)... Can somebody tell me what needs to be done to get rid of this problem? Thanks.

-Jeff
toufu
dopogue
1,773 posts
 
What cartridge are you using (some carts such as Grado are especially susceptible to hum)? When you say you have a ground wire connected from the turntable to the phono preamp, where is it connected at the turntable end? Do you also have a ground wire running from the tonearm to the Creek? Is there a ground connection on your preamp to which you can run a ground from the Creek to the preamp? Hum problems can be very tricky to solve (as you're finding out). You might try starting from scratch with NO ground wires connected and then add one at a time, in various combinations. Sometimes it works best to leave ground wires DISconnected. Good luck, Dave
toufu OP
83 posts
 
Thanks for the help gents.. I have the stock Goldring 1012GX cartridge that came with my MMF5.1. I grounded my turntable by connecting the grounding wire from the turntable ground connector to my phono preamp ground connector. The humming doesn't stop when I turn off the turntable, but it stops when I unplug the turntable's dc adapter.

How do I ground my phono preamp? Connect the ground connector to the amp chasis?

Thanks again..
-Jeff
dopogue
1,773 posts
 
When you say "turntable ground connector," is this part of the connection from the tonearm or from the turntable itself. You do have a ground wire coming from the tonearm, don't you?
toufu OP
83 posts
 
I meant the grouding connector on the back of the turntable in between the rca connectors... The MMF5.1 came with a RCA cable that has the groud wire attached..
dopogue
1,773 posts
 
Okay, there are several steps you can take. Yes, try grounding the phono preamp to your linestage or receiver. Try repositioning the phonostage relative to the turntable and see if you can find a location that minimizes the hum. Try grounding the turntable itself -- not just the tonearm/cartridge -- if you can find a metal connection point under the turntable.

You should take these steps one at a time. It will help if you get (or make) some ground wires terminated with alligator clips -- Radio Shack sells them.

Don't be surprised if at some point the hum just disappears and you can't figure out why. I just went through this drill and that's what happened to me. Good luck, Dave
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