Question about Eltax Atomic A-8.2 Subwoofer

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I have atomic A-8 subwoofer and philips FR740 receiver. when i turn the amplifier and the subwoofer "on", the subwoofer starts to hum loudly and it is wery annoying. i made all the connections perfectly i.e the sub is connected via RCA-cable from amplifier "subwoofer pre-out" to subwoofer.it has been working well, but yesterday evening it started to hum when the amplifier and the sub are "on". volume setting doesn` t help

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David Dunn

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The symptom sounds like an open signal shield somewhere and the cable is acting like an antenna for airborne electrical noise.

Disconnect the RCA cable at the sub. Is it still humming? NO? Problem is external to it. YES? Internal. Broken ground somewhere.

Recheck all connections making sure to twist the RCA head as you install it so oxides will be worn off.

Consider what may have changed in the environment regarding electrical devices, motors, magnetic sources. Ensure signal and speaker wires as ar not running are as non-parallel to any power cords as practicable.

Posted on Apr 23, 2011

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Infinity tss 750 sub-woofer when powered on immediately pulls speaker in and has loud humming. no inputs hooked up, only plugged in to ac power source.


The loud humming is the sound of AC mains - clearly your amplifier is receiving an input from somewhere and possibly into the front end.

The hum could be induced by radiated energy from nearby unshielded equipment, it could be the result of an accidental hum-loop or could be because the amplifier power supply has a fault.

It is usual practice with amplifier construction to ensure unused inputs are shorted to ground by switching or by additional contacts and wiring at the input sockets. High gain high impedance inputs can cause a great deal of unwanted noise if they are not shorted.

I suggest you read the instruction manual and perhaps Google a few hints and tips about amplifiers and stuff.

Mar 28, 2016 | Infinity Audio Players & Recorders

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Klh powered subwoofer model ASW10-120B... when you plug in to power... it makes a loud buzzing/humming noise


I would check the caps on the power supply. They are rather large electrolytic capacitors that will look like they burst and/or leaking. When these die, the caps ground and the sub will make a loud buzzing sound. If you are handy with a soldering iron you can replace them yourself. Replace them with the same voltage or a little bigger and same with the size.

If the cap. says 16v 4700pF on it, for example, a 20v 5300pF or a 16v 6200mF cap. will work for this application.

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Jan 05, 2016 | Audio Players & Recorders

1 Answer

Loud hum from subwoofer


The number-one cause of subwoofer/speaker hum is the coaxial cable connecting your cable or satellite receiver to your provider (either through an inground run to a cable box or through a satellite dish). Here is how you test for this:
  1. Turn your system on and get it to produce the hum by watching a movie. Pause your DVD or videotape so that the hum is all you hear.
    TIPDon't use a normal cable or satellite program for this; you're about to disconnect the cable that provides the audio and video for your cable/satellite feed.
  2. Find the coaxial cable running from your cable or satellite receiver to your service provider, and while listening to the hum, unscrew the connector and disconnect the cable.
Did the hum stop or reduce by a large amount? If so, the cable you disconnected is the source of the noise. If this is the problem, you have several ways to fix the issue permanently (if not, jump ahead to the next section):
  1. Call your cable or satellite company and ask for a service call. Sometimes you get a smart cable guy, and if you demonstrate the problem he can do something upstream to ground the coaxial cable and remove or reduce the hum.
  2. Buy a power strip that has F connectors as part of its surge protection. Plug the strip into the AC outlet and feed your main coaxial signal through these connectors. This ties the shielding of the coax (the source of the noise) to your AC ground and sometimes can solve the problem.
    WARNINGOddly enough, this solution (surge protection) can sometimes increase the humming.
  3. Go to your local RadioShack store and buy three inexpensive items: a Matching Transformer (part #15-1253), an Indoor/Outdoor Matching Transformer (#15-1140), and a Cable Coupler (#278-304). Connect your coaxial cable to the cable coupler, and then to the first matching transformer. The output is two screws for the old two-wire antenna wire. Your indoor/outdoor matching transformer has two connectors for the screws, and the other end is a coaxial connector. Hook your cable or satellite receiver into this connector and see if the hum goes away.
Here is why this trick works: the first transformer converts your 75-ohm coax into a 300-ohm antenna connector. The second transformer converts the 300-ohm back to a 75-ohm connector. The humming, which usually is at around 60 Hz, can't pass through these conversions.

Ground Loop Hum

The second cause of hum is called a ground loop, and it almost always shows up right after you bring home a brand-new, self-powered subwoofer, or perhaps an external amplifier.
Take a look at all the plugs on the power cords on your home theater equipment. In most systems, the receiver (or amplifier) has a three-prong power plug, but most of your other devices have only two-prong plugs. This is not by accident; the device with the three-prong power plug is grounded. This means that device "owns" the ground. As long as no other power device has a three-prong plug, everything works well.
When you bring home a self-powered subwoofer and plug it in, though, you might notice it has a three-prong plug; this is for safety reasons. However, when you connect an RCA cable from your receiver to your subwoofer and turn everything on, you suddenly notice a loud hum.
The external amplifier in your subwoofer is now fighting with the amplifier in your receiver for possession of the ground. Both devices want to define 0.00 volts. But because the wiring in the two amplifiers to your household AC ground is different, one device is really using 0.001 volt and the other device uses something closer to 0.003 volts. The subwoofer cable connects the two, and the fighting begins.
You have to stop these two devices from trying to own the ground, or get them to not "see" each other. First, make your system produce the humming noise. Disconnect the single RCA cable between your receiver and subwoofer. Did the noise stop? If so, you have a ground loop issue.
The proper, safest way to solve this problem is to buy a special subwoofer cable with little arrows on the wire to show the signal direction (see ).
[img src="http://oreilly.com/images/hacks/htheaterhks/figs/htheaterhks_0601.jpg">
Figure 1. Subwoofer cable with directional arrowUnfortunately, many people have been ridiculed when asking about these sorts of cables at their local electronics store: "But cables don't really have a direction. My expert friend at work laughed at me when I asked about this!" Yes, your friend is right. Cables don't have a direction, but these little arrows indicate that this cable will prevent or solve your ground loop problem.
Remember when I said the hum started when you connected the RCA cable? That RCA cable really contains two wires: the center wire and something called the shield. The center wire carries the audio signal, but the shield tries to define 0.00 volts. The shield is the wire that lets the two different components (the receiver or amplifier, and the subwoofer) see each other's ground, and causes the fight. What if you took your subwoofer cable and disconnected the shielding from just one end? Wouldn't that solve the problem? Yes, it would. This is exactly what a subwoofer cable with little arrows does. The shield is not connected at both ends. The shield has to be connected at one end, for connecting to your receiver or amp, so you should run the cable so that the arrows show the flow from the receiver to the subwoofer.
WARNINGIt is unsafe to use a two-prong to three-prong "cheater" plug on the subwoofer power cord to solve the hum problem. Even if the subwoofer came with a cheater plug in the box, it's REALLY not safe to do. Don't do it.

Sep 01, 2013 | Denon Audio Players & Recorders

1 Answer

The subwoofer makes a humming noise when powered on


Humming , these depends on what kind? or how loud is the humming.

On most it is from faulty regulator or worst from the amplifier and preamp

These may needs further troubleshooting, have a tech to guide you.

Let us know what you find or needs further assistance.

Oct 31, 2012 | Audio Players & Recorders

1 Answer

Subwoofer will not produce sound. Connections are correct. I do hear a hum or a crackel as I pull the connection on and off. AVR-689 model


In order to ensure output to your subwoofer: make sure the subwoofer is connected to the subwoofer out of your amplifier and make sure that your amplifier/receiver is set to output multi channel sound

May 07, 2011 | Denon AVR-689 Receiver

1 Answer

After a power outage I have a loud hum.


Hi, The Ground Rules Of all the annoyances that can afflict any audio/video home theater or even a simple stereo installation, the notorious "ground loop" may well be the most difficult and persistent one to track down and eliminate. A "ground loop" is caused by the difference in electrical potential at different grounding points in an audio/video system. (All the grounds in an A/V system should ideally be at "0" potential.) A ground loop typically adds a loud low-frequency hum or buzz as soon as you plug in any of various audio or video components, including subwoofers, cable-TV outboard boxes, satellite-TV feeds, TV displays, amplifiers, A/V receivers or turntables. The buzz/hum is a byproduct of the multiple power supply cables and a ground voltage differential within your system and its network of interconnecting cables.

Here are some methods to help you get rid of ground loops. Try these first and don't waste money on a power "conditioner" which, in most cases, won't help. (There is no need to "condition" the AC power for your system. Your receiver or amplifier already has a power supply with its own filters and transformers. No further filtering is normally required.)

If you get your system up and running and hear an audible buzz or hum, the first culprit to look at is either the powered subwoofer or your cable-TV or satellite-box feed at the entry point to your system.

First, the subwoofer: unplug the coaxial cable that connects to your powered subwoofer to see if the ground-loop hum disappears. If it does, it's likely coming in through your cable/satellite TV feed.

Reconnect your subwoofer's coaxial cable from the subwoofer input to your receiver's subwoofer output and disconnect the cable-TV feed (or satellite feed) from your outboard set-top cable box or satellite tuner. Be sure and disconnect the cable before any splitters. Now see if the hum/buzz from your subwoofer stops.

If that eliminates the hum, you can install one of these inexpensive in-line ground isolators from Parts Express or Bass Home. Note that these transformer-based ground isolators will work fine with analog cable-TV feeds, but depending on their design they may interfere with or block reception of HDTV signals via a digital cable or satellite dish feed.

Install the ground isolator between the cable-TV feed and the input of your outboard cable-TV box or satellite tuner (or the TV display's antenna or cable input if you have a set with a built-in TV tuner or a cable-card ready set). In many cases, the ground isolator will "break" the loop and remove the annoying hum or buzz by isolating the TV-cable ground.

If a hum remains with the TV cable completely disconnected from your system, or you don't want to risk degrading reception of HD signals from a cable or satellite system, then you may have to add a ground isolator like this Radio Shack Model 270-054 between the line-level coaxial subwoofer cable from your A/V receiver and the line-level input jack on your powered subwoofer.

In all cases, if your subwoofer has a ground-lift screw like some of Axiom's subwoofers, try first removing the screw (or replacing it) to see if it increases or eliminates the hum. It may or may not make a difference.

If you do not have easy access to the aforementioned ground isolators, here are a few more tips:

Try plugging the subwoofer into a different AC outlet in the room, one that isn't supplying power to your components (A/V receiver, TV, cable box, etc.). That might fix it.

Try reversing the AC plug for your A/V receiver or the powered subwoofer. If it's a 3-wire plug or a polarized plug, which has one prong wider than the other, you won't be able to reverse the plug. For safety, do not use a "cheater plug" to bypass the 3-wire plug.

With the power OFF, reverse the AC plugs one by one of any other components that have a standard 2-prong AC plug that isn't polarized. Each time you reverse a plug, turn on the system with the attached component and your subwoofer and see if the hum disappears. In some cases, reversing one or more plugs will eliminate the hum.

If you have a turntable, try connecting a separate ground wire to a chassis screw on your preamp or receiver and see if the hum disappears. If you already have a turntable ground wire, try removing it from the preamp. One or the other may eliminate the hum.

Finally, here is another solution that worked well for a member of our message boards who decided to discard his ground-loop isolator on his subwoofer: "I took off the ground-loop isolator I'd been using and connected a plain 14-gauge wire to chassis screws on the sub and the receiver then powered everything on. Although hum was still there, it was far lower than before. Next I unscrewed the ground-loop screw on the back of the sub and that took care of the hum completely."

Almost certainly sounds like an earth loop to me, but can be caused by a poorly made transformer or phase shifts on the mains supply. Visit some power conditioner web-sites like Isotek or Isol-8 (or google "earth loop") where there's plenty of advice on how to reduce/eliminate earth loops and other causes of mains-induced hum (transformer problems etc).

Hum on the speakers usually indicates that there is a DC voltage on the speaker line. DC voltage on the output lines would be caused by a shorted output transistor.


Have a nice day...

Feb 16, 2011 | Cambridge Soundworks BassCube 12 Speaker

1 Answer

Sub has started humming with amp turned off. just turned on at wall switch.nothing running


If the hum is from the back of the unit around the amplifier, it may be the transformer. It could be that the mounting is loose.
It could also be that the transformer is going out.

Disconnect all the inputs to the unit, Still hum?

If the hum stops you have something causing noise to the input.

If you have it on a switched circuit, try moving the power plug to a different outlet that is not on a switch. If hum stops, then you have something on that circuit causing the problem

if all inputs are disconnected and it still humms good chance it is the transformer.

Nov 12, 2009 | Velodyne CHT-8 Subwoofer

1 Answer

Subwoofer hum -MTX12" connected to a Aiwa Surround sound. No problems first 10 months, then suddenly all the subwoofer will do is humm loudly and not play music. Changed cables, no change, changed where it...


I assume this is an active sub. The amplifier has most likely failed. You have proved the signal source is not the problem, well almost if you can sucessfully connect the aiwa sub to another amp then we will know for sure. Usually amplifiers fail with an output device short circuit. The hum you here is the power supply direct on the speaker, I would not leave it on for long or speaker damage may ensue.

Sep 21, 2009 | MTX 12" 2-Way Professional Loudspeaker...

1 Answer

No output to subwoofer.


no that is normal if it does it wile using and ur not touching it make sure power plug isnt touching the coard. and some anps do that when they r turned up to loud. or worn input or output plug

Sep 10, 2009 | Onkyo TX-SR601 Receiver

1 Answer

Loud humming sound from subwoofer


just try leaving it unplugged for a while thats what i did and it fixed it

Sep 21, 2008 | KLH PSW8100-8 Subwoofer

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