What would cause this buzz?

Pycroft

Hi all,

I have listened to my new Musical Fidelity m6i integrated, and am loving it. Up until now I have only listened to cDs and no problems. Today I tried a movie. I have my avr pre outs connected to the aux/ht switch on the amp. There is a switch that can make it an aux input, or ht which would bypass the volume control on the amp. When I first tried, there was a buzz once I switched to the ht setting. I turned the bd player, avr, etc. off, and when in switched to the aux/ht setting, it buzzed again. I then moved the switch to the aux setting, and it does not buzz. I'm not sure if this is a problem with the unit, or if there is something I should try.

Tanks in advance for any input/advice.

James

Moose68Bash

I once had a similar problem.

It was a ground loop. The only way I got rid of it was by using an optical digital connection between my VCR/DVD player and the preamp. No direct electrical connection between the components. I was told that it is a common problem when a TV setup has a cable connection.

But, I'm no expert. I'm sure others on the Forum can give you more and better comments.

Pycroft

I had a ground loop issue once before in another home. I assumed that this wasn't the case here since I have no buzz when playing CDs. Maybe im wrong?

James

treitz3

Hello James, do you have a cable box or satellite dish hooked up?

Tom

Pycroft

I have an RCN cable box, but it's plugged directly into the tv, not the audio system. Only thing into the amp is the cd, and avr.

James

treitz3

Okay, let's clarify a bit. Is there any cable or IC that connects the RCN cable box to the audio system at all? Even a shared outlet.

Help me to help you.....what exactly is an RCN cable box?

Tom

txcoastal1

treitz3 wrote: »

Okay, let's clarify a bit. Is there any cable or IC that connects the RCN cable box to the audio system at all? Even a shared outlet.

Help me to help you.....what exactly is an RCN cable box?

Tom

Just a cable box...like comcast or TW

treitz3

Thank you, txcoastal1. So Pycroft, is there any cable or IC that connects the cable box to the audio system at all? Even a shared outlet.

Tom

tonyb

Any audio cable connecting any other piece of gear can transfer the buzz. That's why ground loops are so hard to track down.

First decide if it's the amp, with the amp plugged in and speakers attached and the HT pass thru engaged, nothing else connected, no avr or cdp or tv/cable box....is there still a buzz ? If not, the problem lies elsewhere. Whats everything plugged into ? PC...One wall outlet ? Cables good ?

You can try a cheater plug on the AVR, or try another set of analog cables going from the receiver to the HT pass on the MF.

Pycroft

There is an HDMI wire that goes straight to the tv and does not go to the audio. The cable box is plugged into my monster power conditioner, which is plugged into the same outlet as the amp, which goes directly into the wall. This was the same setup I had for a different amp, and no problems before this.

RCN is the cable company :-)

Thanks for the help

Jmes

cnh

txcoastal1 wrote: »

Just a cable box...like comcast or TW

+1, RCN is one of the local providers of programming in that area.

cnh

cnh

I think treitz3 is on the right track. I've had different equipment hooked up to the same outlet as my TV and cable and on some, no problem. But when I hooked up the Nakamichi pre-amp below it went berserk, had to put a cheater plug on it to stop the noise. BTW the Nak was a NOS piece of equipment, a back up, never used by the original owner on Audiogon. Pristine, not a mark on it.

cnh

Pycroft

Problem found - thanks.

Didn't know you could have a ground loop that affected one piece of equipment and not another.

James

Zentish

Ground loops seem strange until you understand them.

If the incoming cable is at a different ground potential than the local home power, then there's basically a current flow between them. The current flow causes the hum in your system. Any copper interconnects can cause equipment to be affected by the ground loop. You will likely find that equipment with only 2 prong power connectors is unaffected, and equipment with 3-prong grounded power is affected.

You can test this by performing "ground isolation" or "lift the ground" test: disconnect the outlet power ground from all your gear with a 2 to 3 prong adapter - you should not hear the buzz any longer.

It's not recommended to leave your gear un-grounded though. Once you know what it is there are some remedies, including calling the cable company and complaining that there's a ground loop in the line that they need to fix in your neighborhood.

Msabot1

A lot of those CATV companies think that ground is something you grow a garden in...good luck trying to explain a ground loop issue to them...

tonyb

Pycroft wrote: »

Problem found - thanks.

Didn't know you could have a ground loop that affected one piece of equipment and not another.

James

So...what was it ? Dead cat wrapped around a power cord ?