Random high pitch noise (2 seconds long or elongated) whilst watching films

[admin_exported]

3 months ago I moved from my parent's house to a flat in central Manchester. Ever since moving out, when watching films on my 'home cinema' setup, there is an occasional high pitch noise that comes in at random points that either lasts 2 seconds, or lasts an indefinite length of time (never shorter than 2 seconds, never between 2-10 seconds).

This is my setup.

http://farm5.static.flickr.com/4141/4779880963_bf0004b150_b.jpg

This is a very homemade setup - I am using an old Amstrad amp (which is fine), a Panasonic Viera 46" plasma TV,two Fidek studio speakers at the front and 2 Yamaha studio speakers at the back with a sub which also acts as a junction box and powers the left and right rear speakers.

Before moving to this flat my setup was slightly different. The DVD was plugged into the mixer using a short phono cable, not a 15m one, and then the cable between the mixer and the amp was also a short phono cable. The only long 15m phono cable used was to run to the rear speakers at the other side of the room.

I usually have a PC running into the mixer too (as I did at my old house).

I have tried probably about 30 different things to try and eliminate the problem and to diagnose where it is coming from. I am absolutely stumped now.
- It isn't the speakers because I have tried many configurations with headphones only and it happens then too. - It isn't the amp because it happens when I just plug headphones into the mixer and not use the amp at all. - It isn't the mixer because I tried cabling it using a splitter so that the mixer wasn't involved at all, and it happens then. - It isn't the cables, nor their length, because I've tried it with different cables, swapping cables, using only short cables, unplugging cables, using only the front speakers with no long cables involved at all (only short ones), and it still happens then - It isn't the DVD player because there is no high pitch noise if I plug the DVD player audio cables direct into the TV and then plug headphones into the TV - It also happens even when the DVD player is switched off - It happens even if I run the audio cables from the TV to the mixer instead of DVD to mixer - It isn't the power sockets because I've tried plugging the amp, mixer and DVD player into an extension lead plugged in at the other end of the room and it still does it (and it won't be the amp/mixer/DVD causing it because I've already pointed out how none of these are causing the problem) - The long cables were originally running alongside a LAN cable and lots of power sockets - to test if it was interference from these, I moved the cables. It still made the high pitch noise - I have tried unplugging my router and repositioning the router (which usually sits on top of the DVD player and is plugged in at the same wall as the DVD player, TV and amp) to see if it is this that is interferring. The noise still occurs - It isn't the rear speakers because it happens when they're off and it happens with headphones as aforementioned - I have also tried the cable configuration that I had at my previous house - the sound is still there[/list]
Has anybody got any idea what the heck could be causing this problem? It is driving me insane!

Someone suggested it could be interference from cab radios?If it is, then it is interfering in exactly the same way with every element of the setup because as aforementioned I have isolated each element (e.g. the amp,the mixer, the cables) and it occurs on every isolation, so if it is interference, then each element is responding in exactly the same way.

Any help would be greatly appreciated.

Thanks

 

[aliEnRIK]

Id try a TACIMA MAINS CONDITIONER. I suspect its RFI in the mains coming from somewhere

 

[Anonymous]

excellent, will try this. thanks very much.

 

[Anonymous]

Hmm, well, got it in the post today, makes no difference.

I've managed to work out though that it's definitely pre-mixer and the noise disappears if I unplug the 3.5 jack from the TV, so it must be coming through the TV or whatever is providing the audio (because as aforementioned it's not just the TV that it occurs through). So it's happening at the TV/DVD end. It seems to be some sort of power interference but I've tried various sockets around the flat, trying different combinations with just the amp plugged in at one end and everything else at the other, and vice versa, and all together, and so on... still does it.

Really winding me up now.

 

[Anonymous]

another test I just did; unplugging the jack from the TV does indeed remove the noise as does unplugging the mixer, as does unplugging the phono inputs from the rear of the amp, which means it isn't the amp, it's preamp and it's premixer. It doesn't stop if I unplug the TV with the 3.5 still in the headphone jack which makes it seem like some strange sort of interference somewhere.

If I test it with a small TV, (3.5 in the headphone jack of this one), the interference is practically non-existent and the noise doesn't seem to occur.

If the main TV is then switched on, depending on the brightness of the image, there will be a slight buzz that changes in tone as the brightness changes. This is even though the 3.5 jack is in the small tv, not the large tv. Again, seems to be power related...

 

[007L2Thrill]

Years ago I had that problem with a pioneer A400 amp, I found in the end it was the earth connection on the AMP, I have no idea if yours is the same.

Just read your first post, the only earth I can see that may be causing it may be the PC, other then that I have no idea.

Hope you get it sorted

 

[Anonymous]

The weird thing about this is it's pretty much impossible to determine exactly where it's coming from. The fact that I can turn the volume of the interference up and down on the mixer means it must be pre-amp, right? But then I think, maybe it's interference from the power socket the amp is using 'travelling' through to other plug sockets, or something.

When you say it may be the PC, is that in consideration of the fact that when I unplug the 3.5 jack from the TV, the sound goes? Or are you suggesting that the interference is coming from the 3.5 jack plugged into the PC? (Because it isn't)...

 

[Anonymous]

this is the noise...

http://www.redlettucecamera.com/pitch.mp3

 

[swiftmick]

Just too much kit playing silly with each other and not doing the mains any good either.

You need to strip it down and sort it slowly, and check all leads when doing it just in case.

try and keep each item as far apart as possible.

 

[Anonymous]

As described I've done it with as least kit as possible. It happens even with headphones and just a mixer. It happens with just the amp. It's worked before at my other house, it's started playing up since I moved out. When feeding audio into the mixer and then into the amp from the PC, there is no interference. So there shouldn't be when it's just the TV/DVD in place of the PC, but there is.

 

[007L2Thrill]

Do you use an aerial? If you do is it a shared aerial is your flat with other people in your block, if so, it may be noise running down the aerial to your TV, try removing just the aerial from your equipment and see if that does anything.

 

[Anonymous]

Yep, done that - tried disconnecting every single cable from the TV and it still makes the noise. Tried disconnecting it all at wall end too; still makes the noise.

Also happens if I replace the large TV with a small TV, but quieter.

 

[Anonymous]

worked it out just now with a friend. had my suspicions it would be this; the lift in my apartment. if you call the lift, it makes the noise.

arrghh..

 

[JoelSim]

Jonnypiano:
worked it out just now with a friend. had my suspicions it would be this; the lift in my apartment. if you call the lift, it makes the noise.

arrghh..

Unplug the lift.

 

[Anonymous]

Hahaha.

The only solution I can think of is to wedge the lift doors open on the ground floor, and put 'out of order' signs all the way up.

I might get evicted eventually though.