# Subwoofer hum



## rickcst (Jan 20, 2015)

Hi,

I did some research on this, and I can't seem to find a good answer under these circumstances.

I just bought a brand new Pinnacle Subsonic subwoofer, and I'm noticing a hum/buzz from the unit. Even if I unplug all rca connections and keep the volume down it is still present. It seems to be quieter on one different wall outlet (and I've tried all outlets in the apartment). Also, it seems to be louder when I put the sub on its intended shelf.

One more thing, I also bought a small guitar amplifier a couple of months ago. I mention this because I also have the same problem with this amp- there is a low hum/buzz with no inputs plugged in and the volume all the way down, on any outlets in the apartment.

Is it possible the problem lies with the apartment building? It's old, built in 1920. 

Any input would be appreciated-

Thanks.


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## Peter Loeser (Aug 11, 2012)

Does the hum get louder if you turn the volume up? Can you tell if the hum is coming from the speaker or the amp? Have you tried using a power conditioner with either of the devices that produced the hum?


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## rickcst (Jan 20, 2015)

Hi Peter,

The hum is at the same level no matter what I do with the volume. And I believe the hum is coming from the amp.

Honestly, I don't even know what a power conditioner is... might it be a possible solution?


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## tcarcio (Jun 27, 2007)

It is not a permenant solution but try a 3 prong to 2 prong adaptor on the subwoofer power chord and see if the hum goes away. That will at least let you now if it is a 60cycle hum from a bad ground or the amp on the sub.


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## rickcst (Jan 20, 2015)

Hey tcarcio,

Actually, the sub has a 2 prong power cord.


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## tcarcio (Jun 27, 2007)

OK Then try a 2 prong to an adaptor with a ground on it.


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## willis7469 (Jan 31, 2014)

Built in 1920. Full of knob and tube. I would try a conditioner also.


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## rickcst (Jan 20, 2015)

Thanks for your replies.

I tried a plug adapter with a ground, and it did not help.

So, it looks like trying a power conditioner might be a solution. Any recommendations on one? Maybe any one will do? I looked on Amazon and saw one made by Furman for around $50- The reviews are good.


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## rkeman (Jan 24, 2014)

Is the hum emanating from the speaker or the amplifier? If the former, it is probably a ground fault or power supply problem in the amplifier. If the latter, the amplifier transformer is probably the source and could be due to DC on the power line.


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## rickcst (Jan 20, 2015)

Hi rkeman,

I believe the hum is emanating from the amplifier. Could you explain more about what you mean by 'DC on the powerline'?

Thanks.


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## NBPk402 (Feb 21, 2012)

rickcst said:


> Hi rkeman,
> 
> I believe the hum is emanating from the amplifier. Could you explain more about what you mean by 'DC on the powerline'?
> 
> Thanks.


If it is coming from the amp... You can disconnect the inputs, and outputs and it should still make the noise, I believe.


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## rickcst (Jan 20, 2015)

Oh thanks. Yes, that is the case. 

So, possibly it could be the amplifier transformer, or the fact that I live in a very old building and have had other hum issues with a guitar amplifier. So, I'm still thinking about the power conditioner solution that a couple of you guys have mentioned. Hopefully that will clear it up... unless anyone else wants to chime in about this issue.

Thank you-


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## rkeman (Jan 24, 2014)

Direct current (DC) on a power line can overload (oversaturate) a transformer and cause the coils to vibrate. This results in the hum. If the transformer is loose, poorly damped mechanically, or is wound too loosely a hum may also occur. The latter will not respond well, if at all, to line conditioning. Relatively few power conditioner block DC and the least expensive one that I have experience with is sold by Emotiva. An internet search is sure to yield other possibilities. Good luck!


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## tcarcio (Jun 27, 2007)

I have this one and I love it. It gives you much more control over your HT like turning things on one source at a time which I like because I have seperete amps. It is a bit more expensive but I beleive it is worth it. https://www.google.com/url?sa=t&rct...hvo38qNI0qrI0l0ENmWgglA&bvm=bv.84349003,d.cWc


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## rickcst (Jan 20, 2015)

Thanks for the info, guys. I learned some new things... I really appreciate it!


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## istvan (Jul 5, 2013)

One thing not mentioned here. You may want to buy a receptacle tester. They cost less than 20$. They have diagnostic LED's and what they mean right on the plug. I found my wall plugs to be wired wrong and some without grounding in my old house.


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## NBPk402 (Feb 21, 2012)

rickcst said:


> Oh thanks. Yes, that is the case.
> 
> So, possibly it could be the amplifier transformer, or the fact that I live in a very old building and have had other hum issues with a guitar amplifier. So, I'm still thinking about the power conditioner solution that a couple of you guys have mentioned. Hopefully that will clear it up... unless anyone else wants to chime in about this issue.
> 
> Thank you-


Any chance you could plug the amp in another outlet to see if it is that outlet causing the problem... Or better yet take it to a friends house and see if you have the same noise?


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## willis7469 (Jan 31, 2014)

istvan said:


> One thing not mentioned here. You may want to buy a receptacle tester. They cost less than 20$. They have diagnostic LED's and what they mean right on the plug. I found my wall plugs to be wired wrong and some without grounding in my old house.





ellisr63 said:


> Any chance you could plug the amp in another outlet to see if it is that outlet causing the problem... Or better yet take it to a friends house and see if you have the same noise?


 +1 
And +1


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## istvan (Jul 5, 2013)

I should add its important to test the entire circuit. Your circuit breakers will let you know which plugs are on the same circuit. The plug you are using might be wired right but that doesn't mean the others are right. Plugs without grounds are still polarized snd that wider prong serves as the "ground" electrically. If some receptacles are reversed then the items plugged into them will "ground" into the live connection at the other receptacle. Finally - having all the audio equipment on the same circuit helps. When connecting low level lines, as you do for a sub, if the amps are on different power circuits there is a greater chance of humming and noise as you are effectively creating a bridge between two high power circuits using a thin wire thats carrying just a couple of volts.


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## Insearchof (Oct 21, 2014)

I had to get a cable ground loop isolator. It's an in-line device that cut my nasty hum in an older home.


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## istvan (Jul 5, 2013)

Insearchof said:


> I had to get a cable ground loop isolator. It's an in-line device that cut my nasty hum in an older home.


In this case the hum is still there when there is no audio input, which leads me to believe its something in the power line and not the signal input. There are ground isolators for audio applications but I don't think they would help here.


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## rickcst (Jan 20, 2015)

I do own a receptacle tester, and have checked my outlets- all seems good. And yes, I've tried the sub in all outlets, same issue. I don't think I can bring it to a friend's place, because I have no car, and my friends live pretty far away.

So, I put some thick felt pads under the metal isolation cones that support the sub (the sub is on a shelf). This has helped the hum quiet down, and it's really only noticeable if I get really close to it. 

I'm going to do some research on all the advice I've gotten and take it a step at a time. If all else fails, I'll live with it (the felt pads really have helped). 

Thanks again for all the help, guys.


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## NBPk402 (Feb 21, 2012)

rickcst said:


> I do own a receptacle tester, and have checked my outlets- all seems good. And yes, I've tried the sub in all outlets, same issue. I don't think I can bring it to a friend's place, because I have no car, and my friends live pretty far away.
> 
> So, I put some thick felt pads under the metal isolation cones that support the sub (the sub is on a shelf). This has helped the hum quiet down, and it's really only noticeable if I get really close to it.
> 
> ...


It makes me think it might be a mechanical noise (maybe a transformer noise?), and not an electrical outlet problem.


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## Rick R (Dec 3, 2013)

ellisr63 said:


> It makes me think it might be a mechanical noise (maybe a transformer noise?), and not an electrical outlet problem.


Ron I think you are spot on, I have read all through this post and all indications are that it is a noisy transformer. I would suggest the OP return it to the place of purchase for testing and if necessary replacement. If it is transformer noise it ain't going to get better, it will with time just get worse. The sub should actually make no noise at all, at least to people with normal hearing, with no inputs and just a mains supply.


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## FargateOne (Mar 3, 2015)

Hello,
I think that I am at the right thread for help.
Since I add Anti-mode dual core 2.0 between my receiver and my sub ( see my system left corner here) I must raise the sub volume which is normal. To give you an idea let say the arrow was at 8 o'clock now it is at 11 o'clock

At this new level I hear a humm and it varies with the volume. Is it normal? Is it the transformer of AM ?


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