Interference through speakers

[grizzlyman]

I just bought a APC H15 and I'm still getting interference through my speakers. I do have florescent lightning near by, is that the problem? Also I ran my cable through it and I still have a bad picture it kinda of looks pixeley and it's not the tv.

 

[grizzlyman]

Starting to run out of ideas

Ok i tried my cable, subwoofer, computer, unplugging and turning off florescent lights, i unplugged everything including tv, XBOX 360, digital cable box nothing has worked yet. It sounds like a buzzing sound coming out of only the tweeters. I have unhooked everything except the receiver meaning I unplugged every other component and all my audio wires going into the back of my receiver and I still have it. Its 66db right at the tweeter.

 

[Davemcc]

Do your speaker wires run near any electrical cables? If there are no sources (esp. cable box) plugged into the receiver, I am also at a loss. What happens when you remove the APC from the system entirely and just have the receiver plugged in directly to the wall with no sources connected?

 

[grizzlyman]

Ok tried just hooking the reciever into outlets. still a buzz. Yes my speaker wires do cross so electrical cords but even with the only thing with power is the reciever which the cord wasn't even close to the speaker wires i still got a buzz.

 

[Davemcc]

Have you disconnected the cable coax line feed from the back of the cable box? Just going through any potential culprits here.

 

[grizzlyman]

Removed cable box completely. Even plugged the receiver it in to a dedicated plug and still a buzz. If this ain't a hair puller, head banger I don't know what is. Heres might be a dumb question. Could my receiver be causing the trouble? The reason I say this is when I turn it on it takes anywhere from 10 to 15 seconds until I hear a click and thats when the audio or buzz will start playing through my speakers. All the lights and screen come on as soon as I turn it on but nothing comes out of the speakers until the click. I think its 4 or 5 years old. Its a Sony STR-DE485

 

[Rickster71]

Could my receiver be causing the trouble? The reason I say this is when I turn it on it takes anywhere from 10 to 15 seconds until I hear a click and thats when the audio or buzz will start playing through my speakers.

Yes. It's starting to seem that way.
Do you have a spare, or a receiver you could borrow for a test?

 

[TLS Guy]

I just bought a APC H15 and I'm still getting interference through my speakers. I do have florescent lightning near by, is that the problem? Also I ran my cable through it and I still have a bad picture it kinda of looks pixeley and it's not the tv.

I feel fairly certain that you are picking up RF interference. This believe it or not is usually picked up by the speaker wires. People have a hard time understanding how speaker wires can pick up radio frequency interference and have it come out of the speakers!

Well this is how it happens. The speaker wires pick it up, but how does it get back to the high gain stages, rectified and amplified and appear at the speakers? The answer is through the negative feedback circuits of the power amps. All power amps have negative feedback, where a portion of the amps output is fed back out of phase to the early high gain stages to cancel errors, i.e. distortion products. This is how you get such low distortion from an amp.

Now the first solid state junction that sees this RF signal, usually a high gain base/emitter junction rectifies it, because solid state junctions are rectifiers also. The RF signal is then progressively amplified by all the following stages and comes out of the speakers.

The biggest source of RF interference in the home is light dimmers. The SCRs in those devices radiate a lot. The next source is fluorescent lights, and the next electric motors. Now all those sources are capable of using the entire wiring of your house to radiate that RF noise.

So what are the solutions.

I personally advise putting speaker cables in steel conduit where possible.

Keep all speaker cable as far away from AC mains cables as possible. The interference will go do down by the square of the distance that speaker cables are separated from AC cables.

Control sources of RF. Use high grade dimmer switches, like the Lutron meastro, through out the house.

Put RF blocking caps across motors that are suspect.

If all the above is impractical, then make RF blocking chokes for the speaker leads

Here is how you make an RF choke for the speakers. Take a half inch diameter ferrite rod about 1 to 1 1/2 inches long. Wind round it 10 turns of heavy gauge solid copper wire, with a slight space between each turn. The type of copper wire you scrape the insulation off. Solder one end to the positive speaker cable and connect the other end to the positive speaker terminal of you amp or receiver. You will need to make one for each speaker that is buzzing.

 

[Rickster71]

You need to isolate the problem to either power problems, or components.

To do that:

Get yourself a power strip or your APC H15, plug all your A/V components into it.
What you are after is a single point ground, and common neutral. Using an extension cord, plug into other room receptacles, to see if another circuit causes the hum to dissipate.

 

[TLS Guy]

You need to isolate the problem to either power problems, or components.

To do that:

Get yourself a power strip or your APC H15, plug all your A/V components into it.
What you are after is a single point ground, and common neutral. Using an extension cord, plug into other room receptacles, to see if another circuit causes the hum to dissipate.

The member stated that he heard the buzz when ONLY the receiver and speakers were connected. Also it is stated that it is a buzz and not a hum. Both these pieces of information would indicate that this problem is RF interference rather than a ground loop.

Ground loops are the commonest problem but right behind is RF interference.

As long as the member is correct that the buzz is present with ONLY the speakers connected, and that means no powered subs, then that absolutely excludes a ground loop and your solutions will be useless to solve his problem.

Ground loops can be tough but RF interference problems are worse to track down and solve.

The reason there is a delay between turn on and the appearance of the buzz it that his receiver must have a circuit to disconnect the speakers for about 15 sec or so after turn on, to prevent turn on thumps being passed to the speakers. This is very common practice.

 

[grizzlyman]

IF I do use a RF blocker your just talking about talking a 1'' to 1 1/2'' piece of wire wrapping it and soldering it to on end of the wire than get
another piece of wire and putting in to the other end. Not running the RF blocker from the speaker the whole way back to the receiver. I was serious I literally had every thing unplugged except my front speakers and
receiver which I did try different outlets.

 

[TLS Guy]

Ok i tried my cable, subwoofer, computer, unplugging and turning off florescent lights, i unplugged everything including tv, XBOX 360, digital cable box nothing has worked yet. It sounds like a buzzing sound coming out of only the tweeters. I have unhooked everything except the receiver meaning I unplugged every other component and all my audio wires going into the back of my receiver and I still have it. Its 66db right at the tweeter.

Please clarify for all. Do you still hear this buzz, when only the receiver is plugged in and everything disconnected from the receiver except passive speakers, no powered sub?

Is the sound a rough buzz higher pitched than 60 HZ or 120 Hz?

If the answers are yes, then you are experiencing RF Interference. You can go to the bank with it. Your solutions are given in my first post. However if you share a grid connection with the same phase as a neighbor and both your connections are after the nearest transformer, then you could conceivably be receiving the interference from a neighbor.

 

[grizzlyman]

Yes with everything unplugged except the receiver I still hear the buzz. Its not high pitch I'd have to say medium to soft you can only really hear it if you get close.

 

[TLS Guy]

IF I do use a RF blocker your just talking about talking a 1'' to 1 1/2'' piece of wire wrapping it and soldering it to on end of the wire than get
another piece of wire and putting in to the other end. Not running the RF blocker from the speaker the whole way back to the receiver. I was serious I literally had every thing unplugged except my front speakers and
receiver which I did try different outlets.

This solution should be your last resort. You have misunderstood my instructions. You need to make a ferrite cored RF choke. You can use the ferrite core of the AM antenna of an old portable radio, if you can't find another source. Cut about 1 1/2 inch lengths, one for each speaker. Now get at least 16 AWG copper wire with the varnish insulation and wind 10 turns around the ferrite core, with a very small or no gap between each turn. Do not overlap the turns. Glue the coil to the ferrite core.

Now remove a little bit of the insulation from each end of the coil wires. Connect one end to the positive speaker terminal and the other end to the positive speaker wire. Do this at the receiver end not the speaker end.

So the RF choke will be in series with the positive speaker cable at its origin. Now all these details are important.

One caveat this choke will probably not remove the buzz completely, but it likely will substantially reduce it. That is why I put that solution last.

 

[TLS Guy]

Yes with everything unplugged except the receiver I still hear the buzz. Its not high pitch I'd have to say medium to soft you can only really hear it if you get close.

That is what RF sounds like when picked up by audio gear. It is high pitched because you are hearing it from the tweeters. The wave is what is called a half sine wave with significant distortion products also present. It is very hard to tell the pitch. The fact that you hear it from the tweeters puts the frequency in the higher end of the audio spectrum.

 

[grizzlyman]

It has to be bleeding down from upstairs. I turned all the circurt breakers off that feed down here and ran an extension cord to an outlet with power and I was still picking up RF noise.

 

[TLS Guy]

It has to be bleeding down from upstairs. I turned all the circurt breakers off that feed down here and ran an extension cord to an outlet with power and I was still picking up RF noise.

You are still misunderstanding. This noise is not coming via the mains directly. RF is radiated by your mains wiring into free space. Yes the air of your home, just like a transmitter. This Radio frequency radiation is then picked up by audio circuits. most often the speaker leads, but form by other parts of the audio chain sometimes. However speaker leads are long and usually unshielded antennae ideal for picking up radio waves. As I explained radio waves picked up by the speaker leads can be rectified and amplified by earlier high gain stages and amplified through to the speakers. You have to understand the basic science of radio waves, their transmission and detection to really understand this.
Please look at my first post carefully. Read it slowly several times. All the information you need is there. After careful reading please feel free to pose further questions. Unfortunately it is clear to me you have not grasped the essence of what I said. That is likely because I'm a deficient teacher.

 

[TLS Guy]

You are still misunderstanding. This noise is not coming via the mains directly. RF is radiated by your mains wiring into free space. Yes the air of your home, just like a transmitter. This Radio frequency radiation is then picked up by audio circuits. most often the speaker leads, but form by other parts of the audio chain sometimes. However speaker leads are long and usually unshielded antennae ideal for picking up radio waves. As I explained radio waves picked up by the speaker leads can be rectified and amplified by earlier high gain stages and amplified through to the speakers. You have to understand the basic science of radio waves, their transmission and detection to really understand this.
Please look at my first post carefully. Read it slowly several times. All the information you need is there. After careful reading please feel free to pose further questions. Unfortunately it is clear to me you have not grasped the essence of what I said. That is likely because I'm a deficient teacher.

By the way don't feel too bad. Believe it or not I had to explain all this to the Lutron engineers, who kindly let me help them upgrade their maestro dimmer.

 

[Rickster71]

My intent was to give a fellow member a quick, and free test to help isolate what may, or may not, be his noise problem.

I find that, objective, systematic testing, to be more helpful than assuming one's perception of what constitutes a buzz vs. a hum.

Often a noise problem can be alleviated by something as simple, as moving the noisy circuit to a different phase in the panel.
That is why I asked him to use an extension cord to test other outlets, in a different room, on a different circuit.

 

[jcPanny]

Speaker Buzz problem.

While a noisey dimmer or lighting could be a potintial problem, it would not be a problem when the lighting is switched off.

I would recommend a couple basics checks before jumping to conclusions and trying to build some elaborate RF filter mechanism:

1. Does the buzz come from both speakers? If it only comes from one speaker and the buzz moves when you swap the speaker positions than it is probably a bad tweeter.

2. Check for the correcting phase and ground on your AC outlets using a $2 tester from home depot. If you are missing the ground or the hot and neutral leads are swapped, it could cause a problem.

3. Plug in the receiver and speakers to a different outlet in a different room. If you have the same buzz on the same channel, it is probably the receiver. Start shopping for a new one. RF energy falls off as the square of the distance so unless you have a 30 amp power cord of wireless router right next to your speaker or cable then it is unlikely that is the problem. Also, most RF sources are in the Megahertz frequency range which you can't hear and your speaker cannot reproduce.