Question about Jensen JHT525 System

1 Answer

Hum in subwoofer

Hum when i plug inline cable

Posted by on

  • Anonymous Apr 17, 2008

    When I plug in the JHT525 powered subwoofer all I get is a loud hum. I dont even turn the volume on. I haven't even plugged the any cables into it, just the power cord and it just hums



1 Answer

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that hasĀ over 10 points.


    An expert whose answer gotĀ voted for 2 times.

  • Contributor
  • 53 Answers

If you have cables hooked up and have not installed them to the components when turned on the speaker will hum.
If your electrical outlet is not grounded properly you speaker will hum.
Personally I'd take it back and get a new one. if you just purchased it.
If this happens again try a grounded curcit first then go from there.

Posted on Jun 24, 2008


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

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="">
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

How do I eliminate the humming on my Vizio VHT-510 system

see this instruction and fix it. God bless you

    • 1
      Disconnect the coaxial cable at the back of the satellite receiver or cable box by unscrewing the coupler on the cable end.

    • 2
      Attach the cable to the RF IN jack on a surge protector and tighten the coupler clockwise.

    • Sponsored Links

    • 3
      Connect a second coaxial cable from the RF OUT jack on the surge protector to the input on the cable box or satellite receiver. If this stops the hum, congratulations: You're done.

    • 4
      Unplug the subwoofer's electrical cord from the power strip or wall outlet if it is connected to the same circuit as the AV receiver. The amp in the AV receiver and the amp in the subwoofer are in conflict over the grounding of the electrical circuit.

    • 5
      Plug the subwoofer into its own surge protector and connect the surge protector to a different wall outlet than the AV receiver uses.

    • 6
      Disconnect the subwoofer cable from the back of the sub and the AV receiver if all other measures fail to stop the humming. Reverse the plug connections so the plug that had been connected to the receiver is now connected to the subwoofer. Turning the cable around may solve a problem known as ground-loop hum by reversing the shielding wire inside the cable.

Read more:

Jul 20, 2013 | Vizio Vht210 2.1 Home Theater Soundbar...

1 Answer

My Velodyne DPS-10 subwoofer hums when you plug in the RCA cable. The hum increases in volume when you touch the rear metal panel.

You have to check the RCA cable to the sub woofer. The RCA cabe have two connections inside it, one is for gain and the other is for ground sheild. If the ground sheild is broken then there will be hum from the sub woofer and it will increase if you touch the ground (rear metal pannel is connected to the ground). Replace the cable and check it again.

Jul 17, 2011 | Velodyne DPS-10 Subwoofer

1 Answer

Have an older (6 + Yrs) VX-10A model, that's worked fine up until now. I recently moved, hooked up the same stereo and surround sound speakers, which worked fine, but the subwoofer made a loud hum as...

Disconnect the input and see if it hums in the absence of an audio source. A bad audio cable shield or unwisely-routed audio cables will allow entrance of unwanted signals from external power sources, magnetic fields, even dimmer-controlled track lights. Sometimes, simply reversing the orientation of the ac power plug can eliminate humming.

Mar 03, 2011 | Velodyne VX-10 Subwoofer

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

Sunfire MK II Subwoofer hum. I have a Sunfire MK II subwoofer that hums when it is plugged in (it even hums when no signal is connected). I've tried multiple outlets on different circuits, but hum...

you have a ground loop issue you could purchase a ground loop isolator, jensen makes them for about 40 bucks.I have discovered that if you have cable tv, unplug the incoming cable in your cable box and see if hum disappears.

Nov 25, 2010 | Sunfire True Sub MK II Subwoofer

1 Answer

How to get rid of the hum

Check your cabling to make sure you dont have a ground fault. if you still have humming, buy a "groundless" adapter for your power plug (takes the ground away) and plug it back into the power outlet and I bet your humming will be gone

May 10, 2010 | Sunfire True Sub MK II Subwoofer

2 Answers

Humming sound in subwoofer after it's been playing for a while

It sounds like you are describing an earth loop problem. I won't go into detail in this post, but try an isolation test first. disconnect everything from the reciever except the sub and try connecting say a BATTERY powered mp3 player or cd player to minimise connections to the electrical mains earth. you could also isolate things by taking your sub to a friend's house and trying it on their system.
If it is an earth loop use a process of elimination to find out which two pieces of equipment causes the earth loop. then apply filtering.
you can buy earth loop isolation transformers for about AU$26 and I've used one on my sub myself. Theyhave RCA (phono)plugs on each end and they connect inline with the signal cable to the sub amp.

as for the thumping sound it might be the speaker protection circuitry cutting off the amp to protect the subwoofer speaker from damaged. This might be triggered if the earth loop sound is causing the sub amp to overload and clip.

Failing this there might be a dried out overheated electro capacitor in the amp circuit causing the hum. Hav a chat to your local electronics person, who should be able to spot it!
Hope this puts you on the right track
Happy Hunting!

Jan 07, 2010 | Sunfire Audio Players & Recorders

2 Answers

When i plug in my subwoofer it has a constant hum

Sounds like you have a bad connection somewhere. Make sure all of your connections are secure. If theres anything that is a little loose you'll get that hum. You might also try replacing your cable too. If it became pinched somewhere it could cause that problem

-Captain Jake

Feb 11, 2009 | JBL PB10 Subwoofer

Not finding what you are looking for?
Jensen JHT525 System Logo

Related Topics:

256 people viewed this question

Ask a Question

Usually answered in minutes!

Top Jensen Audio Players & Recorders Experts


Level 3 Expert

5318 Answers

Don Hart

Level 2 Expert

108 Answers

The Knight
The Knight

Level 3 Expert

74999 Answers

Are you a Jensen Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides