RMB 1095 Hum

[Hoopofficial]

Just received a used RMB 1095. When powered up I notice a faint but audible buzz. Normal? My B&K 200.7 is pretty much silent. Please let me know. Pre-amp is not in yet so I can't run it. I'm sure it is fine but being used I wanted to make sure. Any responses are appreciated. Thanks.

[Kevin D]

Buzz from the speakers or buzz from the amp?

Kevin D.

[Hoopofficial]

Buzz from the amp. No speakers or interconnects are connected. Plugged the amp in and turned it on and there is a buzz.

[Kevin D]

Yes the transformer in some 1095's have been known to buzz. Nothing wrong unless it bothers you.

KEvin D.

[Hoopofficial]

Kevin D, thanks for he response. As long as it does not get worse over time or transmit to my speakers I think I will be OK. It is just irritating that a $2k product (new) has this issue. I'm glad I bought it used and paid much less. I will be connecting when my pre-amp arrives so I will find out soon.

[PewterTA]

You might find as I did that once you connect things, the buzzing stops. If I have nothing connected to mine and power it on, it makes a small buzzing noise, as soon as I connect a speaker and interconnect (doesn't matter which or where) it stops all together. I just assumed it's the fact that it has nothing to drive speaker wise.

[kpodolski]

My friend had a 1095. When he got it home and hooked up the transformer buzzed terribly. We checked all of the usual suspects without change. For shits-and-giggles we metered his wall socket. He was pulling down 140+volts! He had to call the power company and they sent out a tech who could not believe he was getting voltage that high through a 110 circuit. He did something out on the pole which corrected the voltage problem and the buzzing transformer. Food for thought...

[Hoopofficial]

Yes, the transformer buzz stopped buy now I have the dreaded ground hum. What can I do to correct this. The amp is fantastic buy the hum is driving me crazy...HELP!

[Legairre]

Is 1095 plugged into the same outlet as the pre/pro? Also do you have cable running to the pre/pro?

[Hoopofficial]

Yes, everything is plugged into the same strip. Cable is being fed to pre-amp through component connections. The issue is the cable line since when I unplug the cable line from the wall the hum all but dissappears. The interesting thing is when I unplug the component connections from the pre-amp, the hum is still there even though it is not connected to my preamp. I thought that was strange. I'm looking into the Jensen Ground Isolator but looking for other alternatives too. Any ideas. I love the amp but it seems to be very sensitive to ground issues from what I read. It has made my B&W 803n really sing.

[Kevin D]

The coax will ground through the outlet on the cable box, thus still connecting it to the amp. Part-express has an in-expensive isolator you can try before the Jensen. You can always call the cable company and tell them to ground it properly.

Kevin D.

[bigburner]

Make sure that your interconnects are physically separated from your power leads.

I spent months trying to get rid of a nasty hum only to discover that the spaghetti at the back was the cause.

Nigel.

[Hoopofficial]

Looked at the Part Express isolator but it is not recommended for digital channels. I have about every possible channel coming out of the box so I do not want to create channel issues. Has anyone tested it with HDTV channels?

[Hoopofficial]

Nigel, all the interconnects I use are shielded. It is almost impossible to physically seperate the "spaghetti" but will take a look to see what is possible. It is somewhat ugly back there.

[PewterTA]

Do you have a power conditioner, something like an APC surge suppressor/regulator. Those (when you run your cable through it and to your box) tend to eliminate the ground loop humming plus protects your equipment you plug into it.

Just a thought if you happen to have one and can test to see if it works or not.

[Legairre]

Yes, everything is plugged into the same strip. Cable is being fed to pre-amp through component connections. The issue is the cable line since when I unplug the cable line from the wall the hum all but dissappears. The interesting thing is when I unplug the component connections from the pre-amp, the hum is still there even though it is not connected to my preamp. I thought that was strange. I'm looking into the Jensen Ground Isolator but looking for other alternatives too. Any ideas. I love the amp but it seems to be very sensitive to ground issues from what I read. It has made my B&W 803n really sing.

As you said your cable line is the problem. Chances are instead of using the house ground the cable company made their own ground.

I had the exact same problem as you with my 1095 and this worked for me. You need to tie the grounds together to eliminate the hum/loop.

1) Wrap a piece of speaker wire around the cable input that plugs into the back of the cable box. Make sure you tie it right around the coax connector that screws into the cable box(or power strip if your cable goes through the power strip) and not on the actual cable box(or power strip).

2) Connect the other end of the speaker wire to the center screw on the outlet(the one that holds the outlet plate on) that the amp or power strip is plugged into if your amp runs through a power strip.

Mine has been hooked up like this for a loooong time with no hum. If I remove the speakers wire that ties the grounds together it hums like crazy, but with it there every is nice and quiet.

[Hoopofficial]

Legairre, thanks for the input. That sounds like a good solution. I have been reading more than I care to admit on Ground Loops and came to the same conclusion about the electric ground vs cable ground. Im fortunate in that my external cable ground and external electric ground are within 10 feet of each other so I am going to run a external ground wire between the two external grounds using ground clamps to see if that works. Since your solution worked, this one should work too. If it doesn't work, I am going to try your solution. I would like to avoid using a Isolator but I want peace and quiet when the music is over.

[Legairre]

Exactly Hoops you have to tie the grounds together one way or another. Let us know how you make out.

[Hoopofficial]

Problem solved. I ran a new external ground from the cable box on my house to the electrical ground and I'm happy to report that the hum is no more. In all I paid $2.75 for a ground clamp. Sure beats the $60 price tag for the Jensen ground isolator Thank you for all the help this forum provided. First with the transformer buzz then with the ground loop. ;x(

[Legairre]

Glad to help Hoops. It's all about getting the grounds tied together. I know everyone says to use the isolators, but to me it's a lot cheaper to just tie the grounds together with speaker wire from the cable wire to the outlet(or component that buszzes) or like you did with the ground clamp. Glad to hear it worked out for you.