HT in a small 10x12 room at around Rs 3.5L

[k-pad]

So, been gwtt

 

[k-pad]

Just noticed my fat fingers screwed up the previous post. And here I was wondering why no help from FMs

So, have recently started getting a very annoying audible hum from the subwoofer, mostly not upon starting the system, but a fair way into a viewing session, say 30 minutes.

It just doesn't go away till I shut the sub and restart again.

After a while of peace, it's all rinse and repeat again.

Checked online, and the consensus seems to be that it is electrical interference.

Now, all my cables are indeed at close proximity to each other and I don't know where to start the troubleshoot.

The subwoofer cable?

Would be much grateful for suggestions.

Thanks

 

[Nitin K]

Just noticed my fat fingers screwed up the previous post. And here I was wondering why no help from FMs

So, have recently started getting a very annoying audible hum from the subwoofer, mostly not upon starting the system, but a fair way into a viewing session, say 30 minutes.

It just doesn't go away till I shut the sub and restart again.

After a while of peace, it's all rinse and repeat again.

Checked online, and the consensus seems to be that it is electrical interference.

Now, all my cables are indeed at close proximity to each other and I don't know where to start the troubleshoot.

The subwoofer cable?

Would be much grateful for suggestions.

Thanks

Hi Kpad,
I am not an electrical expert but pls check if any of the options in the link works.

How to Fix or Eliminate Subwoofer Hum

Learn how to stop subwoofer hum, which is a low-level noise that can be present whenever the subwoofer is turned on, whether or not it is playing.

www.lifewire.com

 

[insane79]

Just noticed my fat fingers screwed up the previous post. And here I was wondering why no help from FMs

So, have recently started getting a very annoying audible hum from the subwoofer, mostly not upon starting the system, but a fair way into a viewing session, say 30 minutes.

It just doesn't go away till I shut the sub and restart again.

After a while of peace, it's all rinse and repeat again.

Checked online, and the consensus seems to be that it is electrical interference.

Now, all my cables are indeed at close proximity to each other and I don't know where to start the troubleshoot.

The subwoofer cable?

Would be much grateful for suggestions.

Thanks

Well, first switch the subwoofer On with only the power cable connected. Disconnect the sub cable & whatever else is connected to it.

If there is a hum then try another power cable, if still present then try another power socket at home for the sub.

With only the power cable connected there is no hum then mostly the culprit is your subwoofer cable.

All the best.

 

[Yelamanchili manohar]

Well, first switch the subwoofer On with only the power cable connected. Disconnect the sub cable & whatever else is connected to it.

If there is a hum then try another power cable, if still present then try another power socket at home for the sub.

With only the power cable connected there is no hum then mostly the culprit is your subwoofer cable.

All the best.

Very good advise. This is the best way to chase hum issues. Connecting only one cable at a time to identify the culprit.

 

[k-pad]

Thanks a ton, @Nitin K, @insane79 brothers.

Tried all the things suggested. The wall unit seems to be the culprit, unfortunately.

Running the sub plugged into the opposite wall using an extension cord for now, while i fix the plug points.

Thanks again.

 

[k-pad]

Thanks a ton, @Nitin K, @insane79 brothers.

Tried all the things suggested. The wall unit seems to be the culprit, unfortunately.

Running the sub plugged into the opposite wall using an extension cord for now, while i fix the plug points.

Thanks again.

Edit: Humming, which wasn't there in the morning over a couple of hours, started around 30 minutes into switching it on now in the night.

Will try a new power cord next, before looking into the wall socket.

 

[Yelamanchili manohar]

Edit: Humming, which wasn't there in the morning over a couple of hours, started around 30 minutes into switching it on now in the night.

Will try a new power cord next, before looking into the wall socket.

There is something coming into your powerline intermittently. Is the hum coming from inside the sub, like from the amp, or is it the sub driver humming. Can you touch the driver when it is humming and can you feel it vibrating.

Since there is no RCA cable connected to the sub, and it is still humming just over the power line, then its :

1. Either a 50hz hum over the power line. Do you have any app on your phone that can measure the frequency of the hum like audio spectrum analyzer or something. If the hum is centered on 50hz, then a power conditioner can help.

2. Otherwise it is DC on the mains and really difficult to get rid off. Many of the claimed DC blockers are hit and miss, and you might have to experiment with a few

I have to rush now, will await your findings. All the best

P.S : If the sub RCA cable is not connected, then it is not a ground loop atleast.

 

[k-pad]

There is something coming into your powerline intermittently. Is the hum coming from inside the sub, like from the amp, or is it the sub driver humming. Can you touch the driver when it is humming and can you feel it vibrating.

Since there is no RCA cable connected to the sub, and it is still humming just over the power line, then its :

1. Either a 50hz hum over the power line. Do you have any app on your phone that can measure the frequency of the hum like audio spectrum analyzer or something. If the hum is centered on 50hz, then a power conditioner can help.

2. Otherwise it is DC on the mains and really difficult to get rid off. Many of the claimed DC blockers are hit and miss, and you might have to experiment with a few

I have to rush now, will await your findings. All the best

P.S : If the sub RCA cable is not connected, then it is not a ground loop atleast.

So, did it again, and was more thorough this time.

Left the power on, and fully detached the RCA cable. No hum with just the power on.

Tried different sockets over three days.

(Also, as you suggested, no driver vibes or hum. It's the amp, most likely. To my ears, sounds like a motor.)

So, veering towards an RCA interference.

Should I try a better interconnect? Current one is some cheap one off Amazon, Blue Rigger or something.

@insane79 @Nitin K

 

[mbhangui]

Just noticed my fat fingers screwed up the previous post. And here I was wondering why no help from FMs

So, have recently started getting a very annoying audible hum from the subwoofer, mostly not upon starting the system, but a fair way into a viewing session, say 30 minutes.

It just doesn't go away till I shut the sub and restart again.

After a while of peace, it's all rinse and repeat again.

Checked online, and the consensus seems to be that it is electrical interference.

Now, all my cables are indeed at close proximity to each other and I don't know where to start the troubleshoot.

The subwoofer cable?

Would be much grateful for suggestions.

Thanks

One quick way to eliminate if the hum is being fed into the RCA input is to remove the RCA cable. Let the subwoofer run without any input. You shouldn't be getting any hum. If your subwoofer runs without any hum for an hour or so, then the problem is not your subwoofer.

EDIT: I just noticed you tried this. Then it is coming from the AMP.

 

[k-pad]

One quick way to eliminate if the hum is being fed into the RCA input is to remove the RCA cable. Let the subwoofer run without any input. You shouldn't be getting any hum. If your subwoofer runs without any hum for an hour or so, then the problem is not your subwoofer.

EDIT: I just noticed you tried this. Then it is coming from the AMP.

Thanks, MB!
It definitely has something to do with the amp. There's a heavy thump when i power off the sub.

Will changing the RCA help?
Or, do i need to write to REL?

 

[Yelamanchili manohar]

So, did it again, and was more thorough this time.

Left the power on, and fully detached the RCA cable. No hum with just the power on.

Tried different sockets over three days.

(Also, as you suggested, no driver vibes or hum. It's the amp, most likely. To my ears, sounds like a motor.)

So, veering towards an RCA interference.

Should I try a better interconnect? Current one is some cheap one off Amazon, Blue Rigger or something.

@insane79 @Nitin K

Great...we are making progress then

If there was no hum for three days with the RCA disconnected, and we are getting hum only after connecting the RCA, then it is definitely a ground loop issue. We have two solutions :

1. Plug the subwoofer into the same main outlet as the other gear.
2. If you dont have an extra socket free, then try to power the subwoofer with a 2 prong pin plug which doesnt have a ground pin from any other available socket in the room.

Either of the above should work in my opinion.

 

[k-pad]

There is something coming into your powerline intermittently. Is the hum coming from inside the sub, like from the amp, or is it the sub driver humming. Can you touch the driver when it is humming and can you feel it vibrating.

Since there is no RCA cable connected to the sub, and it is still humming just over the power line, then its :

1. Either a 50hz hum over the power line. Do you have any app on your phone that can measure the frequency of the hum like audio spectrum analyzer or something. If the hum is centered on 50hz, then a power conditioner can help.

2. Otherwise it is DC on the mains and really difficult to get rid off. Many of the claimed DC blockers are hit and miss, and you might have to experiment with a few

I have to rush now, will await your findings. All the best

P.S : If the sub RCA cable is not connected, then it is not a ground loop atleast.

Not a 50 Hz hum either. More like 170ish.

 

[k-pad]

Great...we are making progress then

If there was no hum for three days with the RCA disconnected, and we are getting hum only after connecting the RCA, then it is definitely a ground loop issue. We have two solutions :

1. Plug the subwoofer into the same main outlet as the other gear.
2. If you dont have an extra socket free, then try to power the subwoofer with a 2 prong pin plug which doesnt have a ground pin from any other available socket in the room.

Either of the above should work in my opinion.

Thanks, Sir.
Will give it a shot soon.

 

[Yelamanchili manohar]

@k-pad ..usually ground loops cause audible hum through the drivers itself. And DC on mains will cause internal hum from transformers. This is mostly 80% of the times. I find the current situation peculiar, in that we are having a transformer hum coming through a RCA cable, which is usually caused by DC. If the above change of power plugs doesnt help, I would suspect some issue with the internal amp and will probably need a thorough checkup by a qualified techie.

 

[Yelamanchili manohar]

@k-pad ..usually ground loops cause audible hum through the drivers itself. And DC on mains will cause internal hum from transformers. This is mostly 80% of the times. I find the current situation peculiar, in that we are having a transformer hum coming through a RCA cable, which is usually caused by DC. If the above change of power plugs doesnt help, I would suspect some issue with the internal amp and will probably need a thorough checkup by a qualified techie.

Thinking further, the last possibility is the subwoofer RCA cable picking up something, probably due to close proximity with another power cord.

 

[Nitin K]

So, did it again, and was more thorough this time.

Left the power on, and fully detached the RCA cable. No hum with just the power on.

Tried different sockets over three days.

(Also, as you suggested, no driver vibes or hum. It's the amp, most likely. To my ears, sounds like a motor.)

So, veering towards an RCA interference.

Should I try a better interconnect? Current one is some cheap one off Amazon, Blue Rigger or something.

@insane79 @Nitin K

Hi K-pad,
Apparently from what I have heard Blue Rigger cables are very tight fitting. You can try Ugreen which is decent for the price & finish. I have a Ugreen HDMI cable & is quite good.
Kabeldirekt is also a good German co. if available at a reasonable price (have this too for the cd player). I have been using Mediabridge Ultra cable for the subwoofer since 2019 and so far no issues at all.

 

[mbhangui]

Thanks, Sir.
Will give it a shot soon.

This looks more like problem in the subwoofer internal amp. When the problems starts happening, leave the subwoofer on and disconnect the RCA cable. What happens then?

 

[k-pad]

This looks more like problem in the subwoofer internal amp. When the problems starts happening, leave the subwoofer on and disconnect the RCA cable. What happens then?

Yes, tried this too, last night.
If I disconnect the RCA cable when the humming begins, it still persists till I power off the sub.

 

[mbhangui]

Yes, tried this too, last night.
If I disconnect the RCA cable when the humming begins, it still persists till I power off the sub.

Is the subwoofer under warranty? I see you are in Mumbai. Both Mumbai and Pune are notorious for stable but constant high voltage due to lowering of voltage standards. I see mostly voltages hovering between 240 to 250 volts. New equipments being imported have to undergo tests for the new standards (in the new standard voltage can go upto 264 volts). Near the power cable inlet what voltage range do you see? The voltage range will also be in your subwoofer manual.

Put a stabilizer before your precious equipments. The standards for voltage regulation in our country has been lowered since 2014 to help few private power companies to install cheaper equipment with lower tolerances. But the actual implementation happened during the covid lockdown. It is now 240 +- 10%. So the stabilizer is the most important equipment as the voltage can be as high as 264 volts. The reason stated is "economic reason" Here is the link https://www.myelectrical2015.com/2019/04/standard-alternating-voltage-and.html. Check this post too https://www.hifivision.com/threads/nad-owners-thread.69476/post-1010431 and See page 25 of the document https://law.resource.org/pub/in/bis/S05/is.sp.30.2011.pdf