Amplifier ground loop

[mafiaahem]

Hi Folks,

Few days ago I installed my new Sherbourn 7/2100A amplifier. I have not connected anything to it; just plugged the two power cords (master and slave) to a surge protector and switched it ON. Immediately I started hearing a low humming sound from the amplifier. From what I have read in the forums and web articles, it appears I am experiencing a ground loop problem. I reconnected the power cords to the wall outlets directly. The hum is still heard. I read that in most cases the ground loop is caused due to the cable box and mostly seen as a low frequency hum coming out of the speakers or seen as lines on video. In my case I do not have the speakers; the hum seems to be coming from the amplifier and easily heard withing few feet from the amplifier. And it is slightly but nauseating.

I have contacted Sherbourn support but would like to know from anyone who is using a 7/2100A what your experience with the amp is. If you have come across this problem, how did you correct it? There are some solutions posted to get rid of ground loops but I would like to know what you did for 7/2100A.

Thanx!

 

[Adam]

My guess is that it is the transformer in the amp that is humming. I get a hum from both of my Emotiva amps (from the boxes themselves...not from the speakers). From what I've read, that is not uncommon in amps.

I don't like the humming either, so I wish you luck in trying to get rid of yours.

 

[Haoleb]

As Adam suggested what you are hearing is transformer Hum. Not a ground loop. You can usually hear it in almost any amplifier when you put your ear right up to the chassis, But from a few feet away could be indicative of possibly a loose transformer mounting bolt. It can also be caused by the power itself. There are times when I can hear my mono blocks humming, But most of the time I cannot.

See what the manufacturer says, Maybe they will replace it because if its that loud it doesnt seem normal.

 

[mtrycrafts]

Do a couple of tests. Plug in just one of the power cords and see if it makes the hum on only one of the sections, then repeat with the other.
Also, since you didn't connect anything to it, try different outlets in the house. Maybe even in the kitchen that has 20A outlets just in case, even though you are not pulling any current.
As was indicated, you have a mechanical hum from the power supply/s.
Best bet right now is the company and tell them that this will not do for you especially if you can hear it so far away.

 

[mafiaahem]

I already tried with just one power cord and I still hear it.

Initially I thought the same: it looked like the mechanical hum from the amp. But reading about ground loops and the fact that there are two power cords made me think otherwise. Your replies give me some relief now. I will wait and see what Sherbourn has to say.

Thanx!

 

[mafiaahem]

Got off the phone with Sherbourn tech support. They say it is not a ground loop situation but actually the mechanical hum from the seven massive transformers that are in there. So looks like I have to move my couch a little away from the amp or just ignore the hum.

BTW friends, I have my first HT setup

This is my gear:

TV: Sony 36" CRT 4:3
Projector system: ---in the works---
DVD: Denon 2930CI
VCR (from the stone age, but still love it): Sony
Preamp: Integra DTC 9.8
Amp: Sherbourn 7/2100A
Speakers: Klipsch RF-82 series
Subwoofer: ---in the works--- (no complaints with RF-82 bass so far)
Cables: monoprice and monster
Gaming: Sony PS2

Thanx!

 

[mtrycrafts]

Got off the phone with Sherbourn tech support. They say it is not a ground loop situation but actually the mechanical hum from the seven massive transformers that are in there. So looks like I have to move my couch a little away from the amp or just ignore the hum.
Thanx!

The reason to try both cables individually is to isolate the sections that may be the cause of the vibration/hum. And since the company indicated the transformer induced hum, perhaps something is resonating. Maybe if you check when you lift it up if it is still there, then maybe pressing on the bottoms of the unit to see if it goes away, isolating a section where it might be resonating, etc.
Or, moving it to another place, out of hearing range

 

[surveyor]

I had a similar problem with my Outlaw audio 770 amp transformers howling. I remedied it by removing any fluorescent lighting from the same room. It's as quiet as can be now.
Kelly

Got off the phone with Sherbourn tech support. They say it is not a ground loop situation but actually the mechanical hum from the seven massive transformers that are in there. So looks like I have to move my couch a little away from the amp or just ignore the hum.

BTW friends, I have my first HT setup

This is my gear:

TV: Sony 36" CRT 4:3
Projector system: ---in the works---
DVD: Denon 2930CI
VCR (from the stone age, but still love it): Sony
Preamp: Integra DTC 9.8
Amp: Sherbourn 7/2100A
Speakers: Klipsch RF-82 series
Subwoofer: ---in the works--- (no complaints with RF-82 bass so far)
Cables: monoprice and monster
Gaming: Sony PS2

Thanx!

 

[mafiaahem]

The reason to try both cables individually is to isolate the sections that may be the cause of the vibration/hum.

I could only try with just the master power cord. The hum is still heard. The manual says the amp should not be switched on with just the slave power cord.

Thanx!

 

[mtrycrafts]

I could only try with just the master power cord. The hum is still heard. The manual says the amp should not be switched on with just the slave power cord.

Thanx!

Yes, as surveyor indicated about the fluorescent light, maybe you can run an extension cord to a room without fluorescent light on or turn the off in the room with that amp and see if that makes a difference.