Hello,

Here is an explanation on ground loops at ePanorama:
http://www.epanorama.net/documents/groundloop/basics.html

Bertus

Hello Bertus,
Thank you for this article, very informative.
So can you Or any One reading this post please suggest a proper grounding scheme for my Project/Amp?

 

Hello,

There is an other page with a "how to get rid of ground loops" at ePanorama:
http://www.epanorama.net/documents/groundloop/

Bertus

 

Hello,

There is an other page with a "how to get rid of ground loops" at ePanorama:
http://www.epanorama.net/documents/groundloop/

Bertus

Hello,
Thank you for the Useful Info. So, is it advisable to Completely disconnect just the ground from left channel's transformer, and ground the left channel amp board with Ground from right channel's Transformer?
Plz refer to the diagram i have attached which shows the GND scheme I intend to do.
Just want to be confident before I try this.
Best Regards

 

Greetings to all Readers,
First of all thank you for reading this post.

I have recently built a Stereo Power amplifier, Both L & R channels uses independent amp boards, independent power supplies (transformers) are used for each channel amp boards, best quality and shielded cables are used, But unfortunately there is a humming sound in the speakers connected to this amp and i hope there is a simple solution for the same.

Description of the problem:-

- No Audio (RCA) inputs connected = No humming at all (FINE)

- If LEFT Audio Input (RCA) connected but RIGHT (RCA) Not connected= NO HUMMING and crystal clear (music) sound from the left channel speaker. (FINE)

- If RIGHT Audio Input (RCA) connected but LEFT (RCA) Not connected= NO HUMMING and crystal clear (music) sound from the right channel speaker. (FINE)

- Now this is when the problem occurs, when Both (R & L RCA) inputs are connected = Humming sound from both the channel speakers. (PROBLEM)
Note: During humming if either one of the RCA L or R input is disconnected, then the humming sound simply stops in both the speakers.

I tried using a different preamp, Mp3 and CD players, but the problem is the same as mentioned above.

I'll deeply appreciate any help, comments and advises, Thank you.

Best Regards.

Hi guys... I have exactly the same simptoms. My amp and power supply design is much the same but share one transformer. Thus I cannot lift common (0V) from ground of one transformer like lubnaan90 did. Any suggestions please!

Thanx alot.

 

I would like to give an update from my previous post in case someone else reads this thread and this might help.

I have solved 90% of the hummm / buzzz problem. What is left is almost not audible. It was a gnd loop problem.

Two mono amps to create stereo each with its own power supply. Now picture the problem. Common point is the transformer, split into two directions left and right channel, the amp inputs running from RCA all the way from the source (CD player).
Picture the 0V point on the transformer secondary as the starting point, everything runs in a big loop from left channel through the left interconnect through the CD player back all the way around through the right interconnect to the right channel back to the transformer secondary 0V. That is the problem.
It was fixed by literary removing all ground connections and connecting them all together at one star point in the amplifier. I made a star point between the two power supplies. Everything is connected to ground there; the transformer 0V, the case (chassis gnd), the AC inlet earth, the RCA input grounds, each (left and right) amplifier ground. The only loop that is left is from the RCA Left input though the CD player to the RCA right input. Not much I can do about that as my CD player and I think most CD players, do not have a gnd connection to real earth.

 

For the benefit of all here are some words of wisdom from Mullard.