Strange noise in studio, EMI, RF????

  • Thread starter Thread starter jamiecer
  • Start date Start date
Hi Supercreep,

Thanks for stopping by. At one point while trying to troubleshoot this noise I turned off every breaker in the house except for the one that the amp was plugged into. I know for a fact that the only thing on that line was the guitar amp. The noise was still there. I live on a one acre lot, do you think that a neighbors baby monitor or garage door opener could still be an issue?

I just spoke to Equi=tech. The are certain that I could eliminate the noise with one of their products. If I were convinced that it wasn't RF I would go for it, but how can I be certain where the noise is coming from? I tried putting a ferrite choke on one of the guitar cable but it made no difference. Does that automatically rule out RF?

Jamie
 
jamiecer said:
I just spoke to Equi=tech. The are certain that I could eliminate the noise with one of their products. If I were convinced that it wasn't RF I would go for it, but how can I be certain where the noise is coming from? I tried putting a ferrite choke on one of the guitar cable but it made no difference. Does that automatically rule out RF?
Click to expand...

Strictly speaking, it would rule out RF above the corner frequency of the choke, provided that the noise was induced upstream of the choke (in the guitar). That might prevent AM radio interference, but I'm not surprised it is doing nothing in your situation.

The difficulty here is that I don't think it's RF interference, it's probably audio frequency interference. For example, aside from the clicking, we know that you have a 60Hz hum problem; that is AF interference, and it doesn't necessarily have to be from a ground problem, it can be quite easily picked up as EMI.

Since there seems to be something odd about your mic pre's outlet's circuit, what happens if you plug the 57 into your preamp when plugged into a different circuit? I am still going to keep coming back to that problem, because if you can't get the dynamic mic quiet, there is not much hope for a guitar.

While you have the multimeter out, test continuity of your mic cables . . . also, connect directly to the mic pre, don't use your in-wall wiring. You need to try to isolate the problem.

What kind of cable did you use for the in-wall wiring, by the way?


Regarding Equitech, an isolation transformer will fix any troubles with the incoming power, but if you have a source of EMI that is affecting the entire neighborhood, it will still impact your guitar. But before you call the utility company, finish troubleshooting your own setup, so you can tell them the problem is definitely not on your end.
 
I just tested the continuity of the mic cable with the multi-meter and my handy-dandy cable checker. 1 - 1, 2 - 2, 3 - 3. When I plugged into the back of the M5 the noise is still there, just lower. I have the mic pre at +58 Pro tools sees the noise at -59.7.

That's really low, I know, but the problem is that is muck louder going through a guitar amp.

The wiring going through the walls and the floor is Canare. The Mic cables are Mogami.
 
Hi,
A fluro turned off won’t cause any noise, and an Ethernet cable away from the audio cables will be fine.
Sounds like you may need a mains isolation transformer, the clicking noise is probably mains switching (signals sent down the cable by the power company) or induced switching noise from something in the neighbour hood Street sign (flashing no right turn) or a large washing machine.
A mains isolation transformer cleans up the mains supply and stops this rubbish getting through, it would be good if you could try one out before buying. Run all the studio power through it except lights. If the isolation transformer works it’s not RF. Here is a link to what the transformers do http://www.raphnet.net/electronique/isolation/isolation_en.php#insulation
If you have 3-phase power coming into the house you could try hooking (by using an electrician) the studio power to a different phase, as there could be a cleaner phase available.
Also try putting down an earth stake (galvanised star picket banged into the ground with about 4 inches sticking out) and connecting this to the original house earth (usually connected to a water pipe) with a fat earth wire.
Also check that the house is actually earthed, I moved into one that had a broken earth wire in the roof that left the house totally unearthed, very dangerous.
Hope this helps

Alan.
 
witzendoz said:
Hi,
A fluro turned off won’t cause any noise, and an Ethernet cable away from the audio cables will be fine.
Sounds like you may need a mains isolation transformer, the clicking noise is probably mains switching (signals sent down the cable by the power company) or induced switching noise from something in the neighbour hood Street sign (flashing no right turn) or a large washing machine.
A mains isolation transformer cleans up the mains supply and stops this rubbish getting through, it would be good if you could try one out before buying. Run all the studio power through it except lights. If the isolation transformer works it’s not RF. Here is a link to what the transformers do http://www.raphnet.net/electronique/isolation/isolation_en.php#insulation
If you have 3-phase power coming into the house you could try hooking (by using an electrician) the studio power to a different phase, as there could be a cleaner phase available.
Also try putting down an earth stake (galvanised star picket banged into the ground with about 4 inches sticking out) and connecting this to the original house earth (usually connected to a water pipe) with a fat earth wire.
Also check that the house is actually earthed, I moved into one that had a broken earth wire in the roof that left the house totally unearthed, very dangerous.
Hope this helps

Alan.
Click to expand...

Pretty good advice, but there are some variations in the US. Three phase residential power is very rare, to say the least. But there are two phases on either side of the panel. Grounding is done with an 8' copper rod, bonded to the existing ground source with #6 gauge copper wire.
 
Problem Solved

It turns out that it was a bad power supply in my next door neighbor's computer. I asked if he would mind shutting down his house and he was cool with it. The first thing he wanted to do was save what he was working on on his computer. I was on the phone with him and when he shut it down the clicking stopped.

What an enormous relief.

Thank you everyone for your help on trying to figure this out.

Jamie
 
You must log in or register to reply here.
Back
Top