Humming in my M&K sub -what can I do?

[Jedi Master]

Unplug the audio cable from the sub and see of the hum goes away. If it does, you have a ground loop and need to use an isolation device for the audio.

Did you connect the ground tab from the cheater to the screw on the electrical box? That needs to be connected for anything to be grounded.

You really should go through the house and check all of the circuits for correct polarity, grounds, etc, and then install grounded receptacles.

Thanks. Update: tried connecting the ground screw from the cheater to the outlet -same problem. Tried plugging into another outlet in a different room, hums like a humming bird.

After reviewing the above comments, I'm leaning toward aforementioned grounding/polarity issues in the outlets, i.e., "earth ground", polarity, dedicated circuit... OR simply internal sub amp issues. At this point I'll take the amp to a shop, plug it in to one of their outlets, and if it hums: service time. If it doesn't, then electrician time. This sucks

 

[mperfct]

After reviewing the above comments, I'm leaning toward aforementioned grounding/polarity issues in the outlets, i.e., "earth ground", polarity, dedicated circuit... OR simply internal sub amp issues. At this point I'll take the amp to a shop, plug it in to one of their outlets, and if it hums: service time. If it doesn't, then electrician time. This sucks

It's better than getting lit up like a Christmas tree due to some electrical abnormalities, right?

 

[zumbo]

Thanks. Update: tried connecting the ground screw from the cheater to the outlet -same problem. Tried plugging into another outlet in a different room, hums like a humming bird.

After reviewing the above comments, I'm leaning toward aforementioned grounding/polarity issues in the outlets, i.e., "earth ground", polarity, dedicated circuit... OR simply internal sub amp issues. At this point I'll take the amp to a shop, plug it in to one of their outlets, and if it hums: service time. If it doesn't, then electrician time. This sucks

To check if you have an earth ground, just go to your electric meter. If it has a wire coming out of it connected to a rod stuck down in the ground, you have an earth ground.

I was not recommending the 20amp outlet/circuit with the earth ground to solve your problem, I was recommending that because your system needs it to protect your investment. A 15amp outlet/circuit will do, but the earth ground is a must.

However, if you are going to invest in a new outlet/circuit, I would go with a 20amp.

 

[Jedi Master]

...Another thing: I can faintly hear a radio (or tv?) broadcast through the subwoofer when NOTHING is plugged into it and it's plugged into an outlet clear in the kitchen! Hmm...is this because the sub doesn't come with a 3-prong plug & therefore, without ground? Are the two issues (humming & radio interference) related?

 

[zumbo]

...Another thing: I can faintly hear a radio (or tv?) broadcast through the subwoofer when NOTHING is plugged into it and it's plugged into an outlet clear in the kitchen! Hmm...is this because the sub doesn't come with a 3-prong plug & therefore, without ground? Are the two issues (humming & radio interference) related?

I am fairly certain a dedicated circuit will eliminate this.

A line enhancer just may as well.

Sending PM.

 

[highfigh]

I should try that, even though I'm happy with things now.

Also, the HumX is a outlet-based solution. Here's a pic...

I hadn't seen that one. I have seen some of their units for guitar amps and effects.

Want to take it apart and tell us what's inside?

 

[highfigh]

To check if you have an earth ground, just go to your electric meter. If it has a wire coming out of it connected to a rod stuck down in the ground, you have an earth ground.

I was not recommending the 20amp outlet/circuit with the earth ground to solve your problem, I was recommending that because your system needs it to protect your investment. A 15amp outlet/circuit will do, but the earth ground is a must.

However, if you are going to invest in a new outlet/circuit, I would go with a 20amp.

The ground rod is probably/usually connected to the panel. Lazy electricians will sometimes use the conduit from the meter to the panel and it eventually erodes from galvanic corrosion.

 

[highfigh]

Thanks. Update: tried connecting the ground screw from the cheater to the outlet -same problem. Tried plugging into another outlet in a different room, hums like a humming bird.

After reviewing the above comments, I'm leaning toward aforementioned grounding/polarity issues in the outlets, i.e., "earth ground", polarity, dedicated circuit... OR simply internal sub amp issues. At this point I'll take the amp to a shop, plug it in to one of their outlets, and if it hums: service time. If it doesn't, then electrician time. This sucks

Get the circuit tester I linked to and you'll at least know which ones are wrong.

 

[TLS Guy]

...Another thing: I can faintly hear a radio (or tv?) broadcast through the subwoofer when NOTHING is plugged into it and it's plugged into an outlet clear in the kitchen! Hmm...is this because the sub doesn't come with a 3-prong plug & therefore, without ground? Are the two issues (humming & radio interference) related?

The TV interference, (RF interference) is a well known problem with class D switching amps, especially poor ones. Those same amps also generate a lot of RF. You are convincing me more and more, that those subs should never have seen the light of day. I would counsel against a repair. A repaired piece of junk is still a piece of junk. I would advise putting you hard earned money into something more worthwhile.

 

[highfigh]

I am fairly certain a dedicated circuit will eliminate this.

A line enhancer just may as well.

Sending PM.

With the sub plugged in but not connected to the rest of the system, I don't know why a dedicated circuit would help. If it was connected to the system, I would agree and do think all of the equipment should be on the same one but in this case, it shouldn't matter unless that leg has a problem.

 

[zumbo]

With the sub plugged in but not connected to the rest of the system, I don't know why a dedicated circuit would help. If it was connected to the system, I would agree and do think all of the equipment should be on the same one but in this case, it shouldn't matter unless that leg has a problem.

Couldn't the interference be coming through the electrical outlet itself? Not sure, just asking.

If there is nothing connected to the sub, it has to be from there, right?

 

[TLS Guy]

Couldn't the interference be coming through the electrical outlet itself? Not sure, just asking.

If there is nothing connected to the sub, it has to be from there, right?

Its not that simple. There are a lot of places were RF can penetrate, including and often the cables to the speaker, in this case the woofer.

 

[zumbo]

Its not that simple. There are a lot of places were RF can penetrate, including and often the cables to the speaker, in this case the woofer.

A line enhancer just may help this, right?

 

[TLS Guy]

A line enhancer just may help this, right?

No! A line enhancer would probably not help. For RF penetrating the mains supply, a simple RF inductor in the mains lead as close to the power supply as possible would be effective, but only for RF penetrating through the mains. It will do nothing for other points of penetration.

 

[mtrycrafts]

I had the same problem with my M&K sub and it was a ground in the interconnect running from the receiver to the sub. Leave the sub plugged in and disconnect the interconnect. If the buzz goes away the problem is probably in the interconnect. Try a new interconnect.

Mike

Mike, that would be true if he had the rest of the system plugged into his sub through the sub interconnect; howere, in that case he could also have a ground loop caused by the cable TV also being connected to a component and nothing being wrong with the interconnect cable.
But, I think he said that everything was disconnected from the sub.