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I have a phonic powerpod 740plus and have connected it to 2 100volt line transformer to 12 toa 30watt speakers when i turn it on it make a humming noise and when i plug in xlr mic leads which i have made from on the wall sockets to plugs useing red black screen cable it makes a load scweeching noise please help to solve this problem for me thanks

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Hi, a couple of questions for you. What pin connections have you made for the cables in the wall. are you using 2 core plus braid mic cable?

Please let me know and we can go from there.

The loud screeching noise you are experiencing, may be too much gain. Start with everything turned down, and work your way back setting levels to about 5-6 from the master level first. The channel gain at the top of each input strip should be you last adjustment.

regards
robotek

Posted on Jun 09, 2008

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A friend who blind has purchase this item some time ago 2007 I believe. We have a number problems with it. 1/ There is a hum of 50 c/s from the deck (I assume from Mains Transformer) when switched on and...


initially it sounds like a ground hum Something is touching ground inside. have you had it open? Look at the out put SSR's and follow them to the out put jacks. can you replace the jacks if need be? have you tried different cables? Does it do it if you use another deck other than the Onkyo. If all looks good and you think the Onkyo is the issue you may have bad IC SSR(s). Do you have the Tech ability to replace the outputs {solid state relays}?
Let us know what conclusions you have come up with. Other wise the sad part is a $110 dollar repair bill or $189 new amp/deck.

Jun 18, 2015 | Onkyo Audio & Video Receivers

2 Answers

It hums when TV ( cable ) is on.


I do see a "Signal Gnd" connection on the rear of your Sony and you can safely try a physical "chassis-to-chassis" ground connection to see if this helps. Otherwise, it could be a defective cable box as the cheaply manufactured "wall wart" power transformers are notorious for poor RF and DC filtering which in turn causes the cable box to produce a 60 cycles hum. Good luck!

Mar 21, 2015 | Sony STR-DE897 Receiver

1 Answer

The subwoofer output on my Kenwood VR-606 has suddenly stopped working. I have tried the "setup" several times, turning the subwoofer off and back on. Also, when I first power up the system, it emits a low...


It sounds like the problem is not with your VR-606. If you hear a hum from the sub, the problem is more likely to be in the sub's built-in power amplifier. However, it is worth resetting the amplifier to factory presets. To do this, unplug the power cable from the mains supply and reconnect whilst holding down the power on/standby key. If the hum persists, connect any powered speaker to the sub-out socket, power on and listen for the hum. If no hum then suspect the powered sub amp. Turn the sub on with no connection to the Kenwood VR-606. If hum persists, the sub has a problem and will need to be replaced or repaired. By the way, you said there is a low frequency hum through the 'speakers' for about 30 mins. Is that all speakers or just the sub? Hope this helps.
Cheers, Don.

Jul 06, 2014 | Kenwood VR-606 Receiver

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 & Video Receivers

2 Answers

I have a Boston Acoustics VR-500 Subwoofer with a problem. As soon as anything is plugged into the line level RCA jacks, the subwoofer produces a loud buzz/hum. I have tried connecting it to the subwoofer...


I'm thinking you have an open shield ground on the RCA input side. Connecting speaker inputs possibly restores the ground. Try connecting the high level inputs then disconnect the remote end of the cables (floating the grounds).

Then get out an ohmmeter and find that open circuitor or bad solder joint between RCA ground and real ground in the speaker's amplifier. Or.... if speaker ground kills the hum and you want to use RCA Line Level input to the sub, just connect one minus speaker output on your source amp to one minus on the sub's amp.

Mar 01, 2011 | Audio & Video Receivers

1 Answer

I have 6 ceiling speakers 8 ohm,how can i connect to receiver htr-6160. Thanks


One way to connect your ceiling speakers is to have a 70V line system.

These would mean installing a step up transformer and individual

transformer on each.


there is also an option of having a volume control on each speaker

Oct 16, 2010 | Yamaha HTR-6160 Receiver

2 Answers

Pioneer Receiver SX-750: Getting a loud hum through the speakers


The hum you hear from the speakers and from the unit itself originate with 60hz AC power. They may not actually be related. Sometimes a transformer will hum slightly and unnoticeably. That you're getting a loud speaker hum says there is an electrical leak or a grounding issue somewhere.

Do all sources produce the hum or, say, just the phono? How about on headphones? Try rotating the AC plug. In those days they weren't keyed with one large blade as they are now.

May 17, 2009 | Pioneer Audio & Video Receivers

1 Answer

Humming noise from all 5 speakers!


check the type of cable you are using. low end cable lets in a lot of static and distortion, if I were you I would look into some higher end cable.
I find 9 times out of 10 with situations like yours the cabling usually is the culprit.

May 04, 2009 | Yamaha HTR-6030 Receiver

1 Answer

A couple of weeks after initial setup of my brand new Onkyo XT-SR606 receiver, I noticed a loud buzzing noise that starts up approximately 10 min after the receiver is turned on. The buzzing is definitely...


The "buzz" you hear is a power hum made by the power supply transformer. It's technically called "Lamination hum" caused by the revering of electrical current through the power supply transformer. In some cases the hum can vibrate the chassis causing other loose material to vibrate. If you can, go to your dealer and check to see if other units of this same type typically make a hum this loud, and if not, see if he can solve the problem for you.

Feb 27, 2009 | Onkyo TX-SR606 Receiver

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