Amplifier hum... loud!! [Archive]

Lowell_M

01-03-2009, 12:20 PM

I am demoing DGK999's Marsh A200s amp this weekend and first hooked it up yesterday. All I did was take my ADCOM amp out of the rack and replaced it with the Marsh with the same IC's, etc. When I powered on the amp, both channels hummed at an uncomfortable level.

If I used a cheater plug from the outlet so that the ground wasn't connected, the hum went away.

I tried to search about this and couldn't find anything and it has happened before at our local get togethers, but I thought I would see what others have to say. What the hell is going on here?

The amp sounds freaking sweet, by the way, after you get rid of the hum.

strider

01-03-2009, 12:27 PM

Sounds like a typical ground loop hum. I'm not certain if there's a downside to using a cheater plug or not, but I've been doing the same thing with my amp for years.

Lowell_M

01-03-2009, 12:30 PM

Yea... finally found some ground loop hum info thanks to FACE. Why would I have the problem with the Marsh and not my ADCOM? Wait a minute!!!!!!!!! let me look at something.... There's no ground on the ADCOM power cord!!

Sorry for the waste of a thread. Problem solved.

MillerLiteScott

01-03-2009, 12:47 PM

Does the Marsh have a ground lug on the back? I have a ground lug on the back of my cd player, integrated, power conditioner and turntable. I have all of them connected to one isolated point. It got rid of the hum I was getting when I played my turntable. Worth a try. Prior to this I had a hum from my CD player and I broke the ground prong off of the plug after I figured out that was my problem by using a cheater plug. YMMV.

Scott

ShinAce

01-03-2009, 12:59 PM

This is why old equipment had the 'ground' screw on the back so you could tie equipment together and get rid of hums.

It has little to do with 2 prong vs 3 prong and more to do with how the equipment is designed. It's possible that a balanced signal wouldn't have this problem, but I haven't taken the time to think it through.

snow

01-03-2009, 03:19 PM

This is why old equipment had the 'ground' screw on the back so you could tie equipment together and get rid of hums.

It has little to do with 2 prong vs 3 prong and more to do with how the equipment is designed. It's possible that a balanced signal wouldn't have this problem, but I haven't taken the time to think it through.Yes if you are using balanced in's and out's you wont have the hum.

REGARDS SNOW