I get an audio buzz on the hifi even with pure sine wave. Any advice?

[Handmade Matt]

Hi everyone. My system's running really nicely thanks in part to support on here.

However.
My Hifi has a buzz on the audio even with my new pure sine wave inverter.
I have bought a mains filter which can be seen HERE but it's not helped.

Maybe it's importnat that the inverter (and therefor the mains filter) is earthed?
What do you think?
A copper rod stuck in the ground?

Has anyone got experience with this audio buzz?
(With my old modified sine wave inverter the hifi itself used to buzz from the back of the unit as well as the speakers (so did my macbook charger when I held it to my ear,) that has now stopped but the speakers still have interference.) When I run the hifi off the grid it does have a hiss, so it's not the best audio equipment in the world but it's definitely more of a buzz and louder with the inverter.)

Thanks again, and all the best.

[Sunny Solar]

It may help if you connect the amplifier chasies to the battery neg (-)terminal. Dont have any component in the hi fi system connected to another "earth" connection..
You could try running a few loops of the speaker wires through a ferite ring close to the amplifier output.

[inetdog]

Hi everyone. My system's running really nicely thanks in part to support on here.

However.
My Hifi has a buzz on the audio even with my new pure sine wave inverter.
I have bought a mains filter which can be seen HERE but it's not helped.

Maybe it's importnat that the inverter (and therefor the mains filter) is earthed?
What do you think?
A copper rod stuck in the ground?

Has anyone got experience with this audio buzz?
(With my old modified sine wave inverter the hifi itself used to buzz from the back of the unit as well as the speakers (so did my macbook charger when I held it to my ear,) that has now stopped but the speakers still have interference.) When I run the hifi off the grid it does have a hiss, so it's not the best audio equipment in the world but it's definitely more of a buzz and louder with the inverter.)

Thanks again, and all the best.

Is the noise present with the main volume control all the way to zero? If so, then the problem is in the filtering of the mains supply of the audio system.
If the noise varies with the volume, it is coming over an input or is from a lower level stage.

There may be a problem between the external source and the amplifier related to what is called a ground loop.
If the mains filter is not earthed to some common point with the earth terminal of the inverter, there can be problems.

If the unit is self-contained or you do not have any external inputs connected, then it really comes down to poor power-supply filtering, which a mains filter may not help with at all.

[Handmade Matt]

Is the noise present with the main volume control all the way to zero?

Yes, volume does not effect the noise.

I'm up for trying a ferite ring, anyone else second that?

[billvon]

I'm up for trying a ferite ring, anyone else second that?

Seconded. It's an easy and cheap fix if it works. Odds are low based on your description but you might as well try it before you move on to more costly remedies (isolation transformers etc.)

[Naptown]

Are any speaker wires running parallel and close to AC power wiring. this can also cause a 60hz hum

[Sunny Solar]

If you try the ferite rings place them as near as possible to the amplifier output. Loop as many times as possible the speaker wires through each ring..
You can try this its cost free to try.. If the speaker cables are fig 8 type.(the usual ) pull them apart after then emerge from the ferite rings.Then lay the on the floor between the amp and the speakers in an evenly spaced randomly haphazard manner. ie.. as in very untidy.
Alsp do the other thing I suggested make a good connection wire between the amp chasies and the battery neg (-) terminal.. Dont have multiple different "earths"

[Handmade Matt]

It may help if you connect the amplifier chasies to the battery neg (-)terminal. Dont have any component in the hi fi system connected to another "earth" connection..

The chassis is plastic. I don't think it's earthed anywhere else. (We have a three pin system in the UK but I'm running my inverted AC power on just two cores.)

Are any speaker wires running parallel and close to AC power wiring. this can also cause a 60hz hum

No, I think at some point they cross an AC wire from the inverter, but there are none running along side.

I have tried ferite rings. I got a back of five.
I have put one on the lead leaving the inverter, one on the mains lead of the hifi and two on the speaker cables (wrapped through three times each close to the amp output.)

...Ultimately I want to replace the hifi for something more efficient, could replacement be a good solution? Is there anything I should look for to be more tolerant of the inverter buzz maybe?


Thanks everyone!

[Sunny Solar]

There are not many specific things to look for when buying an amplifier or any hi fi component that will show one type is better than another for noise rejection.

But I would be looking for an amp with a metal case and old style power transformer. Also keep speaker leads as short as practical. Same goes for amp input cables.

[Handmade Matt]

I have bought a mains filter which can be seen HERE but it's not helped.

Maybe it's importnat that the inverter (and therefor the mains filter) is earthed?
What do you think?
A copper rod stuck in the ground?

Hi everyone. I have solved the problem. I had earthed the mains filter (above) to the inverter and then earthed in inverter to earth. However, now I have earthed the mains filter directly and the buzz has gone. My inverter is no longer earthed. So in short, for further reference: The problem was solved with the mains filter but it needed to be installed properly and earthed correctly (ie. not through the inverter.)
Thanks for all the help.

[inetdog]

Hi everyone. I have solved the problem. I had earthed the mains filter (above) to the inverter and then earthed in inverter to earth. However, now I have earthed the mains filter directly and the buzz has gone. My inverter is no longer earthed. So in short, for further reference: The problem was solved with the mains filter but it needed to be installed properly and earthed correctly (ie. not through the inverter.)
Thanks for all the help.

Glad it worked out. The rule for grounding is that although you do not expect current to flow in the grounding conductor, it is possible that there will be differences in potential between separated earth grounds if there is in fact current flowing in the grounding wires. To reduce audio noise and other problems, a single earthing point is the recommended way to go, with attention paid to any poorly designed equipment that may be using the grounding wire as a current return path (such as by connecting filter capacitors to ground instead of neutral). Since your mains filter may in fact be running current into the earth ground, when you have a choice it should be installed as close to the singe grounding point as possible.