Have my system setup to distribute the video and audio from the Theatre room to the TV in the M Bed room. The audio is using RCA stereo cables and I have to turn the volume way up on the TV to the point that I get a buzz sound also. Is this because the strength of the signal has dropped, it is more on one component then another? What can I do to fix this? My installer just installed a cable that had all 5 cables in one for the component and stereo and is suppose to be able to run this length. Video is fine and the audio is fine from my cable box but not from other components. Audio is fine locally. Is there anything I can do to fix this?
Audio Buzz
- Thread starter Trioxide
- Start date
It may help to know how long is your cable run. A buzz, or hum, is often heard when connecting components via longer cables without shielding. The buzz can be caused by picking up (EMI) signal from the local power supply and devices connected to it. Another potential is a "ground loop" where both sides of the connection are grounded, but there may be some electrical potential between the grounds.
For longer runs of analog audio, it is pretty common to use what is known as "balanced" connections. Such approaches work well to have nice, quiet signals between components. I have used these for runs over 200 feet.
In your case, my first instinct is to ensure you have good, well-shielded cables. This could get expensive, depending on the distance you must run. Another option is to try out one of those wireless interfaces becoming more available at most of the common electronics shops around.
Beyond that, there are interfaces, known as direct boxes, which can convert the line-level signal from (and to) audio and video equipment to the balanced signal described above. I know them as "direct boxes". One near each of the connected devices with a balance run between may very well solve your problem.
Dave X10
Active Member
Are you saying... that it was working correctly... and has since stopped?
Interestingly.. I have had similar mishaps in my own theater. In my case it was merely so many cables in the equipment area that some can get somewhat tight. Then when the equipment area is dusted... the person that does the cleaning can loosen or even disconnect a cable. I would guess it could also be a cable in the bedroom as well.
The cable run is about 70 feet. I had someone install the cable so don't have the specs on the cable, just know it is a combined cable for all 5 lines needed - component and stereo. Some equipment the sound is fine and others I need to turn the volume way up and that is when I hear the buzz much more. Have checked the connections and they are fine.
What I am reading is to use my existing wiring I should look into the "direct boxes"? Is there anything else that can help me? Something to boost the signal so I don't have to turn the volume up so much on the TV?
What I am reading is to use my existing wiring I should look into the "direct boxes"? Is there anything else that can help me? Something to boost the signal so I don't have to turn the volume up so much on the TV?
This description make me, too, suspect that there may be a conncection issue. All connections between audio devices have some level of electrical noise (buzz). I originally missed the point about you having to turn the volume up. Knowing that other equipment works fine tends to point to something other than wiring (but may be a connection issue).
The fact that you are having to turn your volume up until you hear that noise indicates a problem that the signal level (audio signal) is not high enough compare to the noise, known as signal-to-noise ratio. I would expect a proper signal to be able to make it over 70 feet. The problem with wires this long is not loss of signal, but the introduction of electronic noise. Connections can surely be one potential problem here and can cause signal drop where none should exist. Bad connections can also cause additional noise. The fact that your setup works with some equipment and not others would make me consider connections as a likely problem. I would definitely check these, again.
I am also curious about the existing cables. Did your installer put these together himself? Is it possible that there is a connection mid-way, joining two or more shorter cables to make the 70' run? I would make sure that each of the five wires between rooms is a single run, without joints or connections between.
From what in the theater room are you sending the audio/video signal. Is there a way to control volume level from this device? Is it possible that this level is set too low? If you are willing to spend a little money to experiment around, you may consider running to radio shack or fry's and purchasing another long cable (2 wires is enough) to test your connections. Remove the in-house connections from your two audio outputs and temporarily run your new cable to from there to the tv audio inputs. If this solves your problems, then this points to a problem with your cables.
The suggestions to use shielded cable, direct box, balanced connections...all would necessitate replacement of wires. You would not be using your existing wiring. I would consider this to be pretty drastic and would not pursue it until we make sure that simpler solutions don't solve your problem.
FaderJockey
Member
Which source has the low level? Are the outputs switchable between 'fixed' and 'variable'? Does the source have a level control that may have been inadvertently reduced? Has anything been moved or installed that could have pinched an interconnect somewhere?
All my devices, DVD Player, PVR, etc are hooked up to a switch and then travel along the same cable from there to the bedrm. So I know it is not that cable as it works fine for some devices. Therefore it might be the cable running from the device with the problem to the switch. Will try that or it is just that that device has a lower output.
It sure sounds to me like the most likely sources of problems. Based on your latest postings, the lower output seems like a good bet to me.
pete_c
Guru
I have a very old electronic Sima AV switch in the MB which after a period of time develops both audio and video noise. I typically just unplug the power and plug it back in. I have the legacy video/audio TV out to the Sima box. The DC adapter might be the problem.
I remote audio/video/IR from this MB area to an LCD I have mounted in my home office. The "run" was only maybe 20 feet or so but utilize "rapid run" cables for my audio/video feeds and the picture and sound is decent. I also used "rapid run" cables from the family room to one of three LCD's in the kitchen area and the quality of the picture /sound is good.
I remote audio/video/IR from this MB area to an LCD I have mounted in my home office. The "run" was only maybe 20 feet or so but utilize "rapid run" cables for my audio/video feeds and the picture and sound is decent. I also used "rapid run" cables from the family room to one of three LCD's in the kitchen area and the quality of the picture /sound is good.
mdesmarais
Active Member
Yup, low output on one/some devices seems likely. Is it a passive switch? You may be able to fix it by putting in a pre-amp after the switch. If it is an active switch, you might try swapping inputs around, you could have a bad one.
KentDub
Active Member
I agree this sounds like an issue between variable and fixed volume devices, because of the mentions that it used to work. If you indeed confirm it is a variable output, you want to turn the volume up to approx 96% (unity gain) on the source device, and control your televisions volume exclusivly from the television (Make sure the speakers on the source device are off if you turn it up that high!).
It is also very possible that you inadvertantly created a ground loop. These can be created by coupling the grounds from two circuit breakers. These can also be very hard to detect the offending device (For my mixer, which has over 200 cables to/from it, I had a ground loop..... In the end, after rewiring it multiple times, I found it was the damn firewire cable going from my computer to my sound card creating the loop!). Consumer A/V is very subject to ground loops.
One easy thing to try to see if this is indeed a ground loop issue is to 'lift' the ground. You can do this by disconnecting everything from your MB television except for the singal from your HT and power. Get a 2 to 3 prong power adapter from the hardware store and use that to plug in your television (assuming it had a 3-prong power connector to begin with - it may not). That should decouple the ground from the television and prevent any loops. If your TV only had a two prong power outlet to begin with - then it is possible that some other device you had connected was 3 prong, or attached to a 3 prong device (perhaps a x-box360, or local cable tuner). This is not the only way to tell if it is a ground loop, or is it with 100% accuracy, but it is fairly easy to start out with.
+10 on ballanced audio - however I would exhaust other options before going the rewire route (If it is a ground loop and you run ballanced cabling, you'll have the same issue!)
Let us know how it goes,
Kent
It is also very possible that you inadvertantly created a ground loop. These can be created by coupling the grounds from two circuit breakers. These can also be very hard to detect the offending device (For my mixer, which has over 200 cables to/from it, I had a ground loop..... In the end, after rewiring it multiple times, I found it was the damn firewire cable going from my computer to my sound card creating the loop!). Consumer A/V is very subject to ground loops.
One easy thing to try to see if this is indeed a ground loop issue is to 'lift' the ground. You can do this by disconnecting everything from your MB television except for the singal from your HT and power. Get a 2 to 3 prong power adapter from the hardware store and use that to plug in your television (assuming it had a 3-prong power connector to begin with - it may not). That should decouple the ground from the television and prevent any loops. If your TV only had a two prong power outlet to begin with - then it is possible that some other device you had connected was 3 prong, or attached to a 3 prong device (perhaps a x-box360, or local cable tuner). This is not the only way to tell if it is a ground loop, or is it with 100% accuracy, but it is fairly easy to start out with.
+10 on ballanced audio - however I would exhaust other options before going the rewire route (If it is a ground loop and you run ballanced cabling, you'll have the same issue!)
Let us know how it goes,
Kent
Yep. If it's just a device or a few but not most devices on a switch I'd remove the switch from the equation and test direct to the source.
I had my brother complaining that he was getting a "buzz" when he used his PC to send audio to his garage. Turned out that his new PC speakers were really sensitive so he turned down his PC (source) audio. This forced him to crank the amp in the garage which was merely amplifying the noise in the run.
Once I showed him the input adjustment on his PC's speakers his garage "buzz" was essentially gone.
I had my brother complaining that he was getting a "buzz" when he used his PC to send audio to his garage. Turned out that his new PC speakers were really sensitive so he turned down his PC (source) audio. This forced him to crank the amp in the garage which was merely amplifying the noise in the run.
Once I showed him the input adjustment on his PC's speakers his garage "buzz" was essentially gone.