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schrecster
Contributor
Joined: 15 Feb 2010
Posts: 32
Location: Plain Old Texas
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 Posted: Thu Apr 01, 2010 12:33 pm Post subject: |
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| Mike Sommer wrote: |
You can go even further by installing a 240-volt circuit line to your studio, and getting a rack mounted isolation transformer with splits to 20-amp breakers; creating your own isolated service. |
what would something like that cost? |
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Mike Sommer
A Hundred Dozen
Joined: 05 May 2008
Posts: 1222
Location: Boss Angeles
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| Posted: Thu Apr 01, 2010 10:54 pm Post subject: |
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| glenspot wrote: | | But, my THEORY, is that our laptops are taking 110 household current and converting it to a much lower voltage. No matter how good the grounding in your house or studio is... the power supply is the source of the voltage going into your laptop. Most laptops I have seen are powered by a 2 line cord...meaning that the 3 prong 110 AC (positive, negative and ground) is converted to just positive and negative. So, no matter how clean or grounded your household current is (or isn't) it's the laptop power supply that is the final source of noise. |
Glen,
You are almost right. Earth ground is also us to stabilize the power coming into your home. If you open your electrical panel (WARNING!! Don't Open your electrical panel Unless you are qualified to do so. IT CAN KILL YOU!) you will note that the ground bus bar is connected to the common bus bar- it's not "uncommon" to find the ground wires connected directly to the common bus bar. Remember the ground wire is only a backup connection back to the box so that the breaker will trip when there is a short.
The buzz and hum is not just coming from the ground its actually coming through the common line
This is why it's so important that the soil resistance needs to be so low, so that the radio frequencies are pulled into earth, not our gear.
Somany things in our home cause noise in our electrical. An Uninterruptible Power Supply (UPS) can back-feed noise into a system from 30-feet away. So can computer switch mode power supplies.
The thing that most people don't understand is that, one pice of gear could be exacerbating a problem from another peace of gear that's in a completely different room. I'm sure you've experience someone next door running a drill or power saw and seeing snow on your TV, or you can hear the sound trough your speakers, and this was someone next door- this is the same thing. And the problem that started this thread may not be the ground, or the computer but the power supply in the preamp, or a wallwort powering the phone in the next room. The only to real way find the problem is to power down the whole house, find the circuit that feeds the gear, and go through each circuit one by one until you find the problem.
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schrecster
That would depend on may things.
Getting an electrician to pull the service to your studio: Days labor $500 to $800.
K Rated Triple Shield Isolation transformer $1500 to $3000 (maybe less)
And a distribution panel. Cost- depends on how many outlets you need $200.00 to $1500.00.
This may seem like a lot, and it is. But if you're in a studio 8 to 15 hours a day, 5 to 7 days a week. And you consider how much better your equipment runs and how much longer it last, an how much it all cost -including your computer. Consider this: if you are high end a Mac Pro tower will cost you $5000, plus the monitor, a really good condenser mic $1500+, Preamp, compressors, mixers, ISDN- It all ads up, and it's your livelihood we're talking about here. This "pice of mind" pays for it self many times over.
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The Blog:
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Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong. |
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schrecster
Contributor
Joined: 15 Feb 2010
Posts: 32
Location: Plain Old Texas
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| Posted: Fri Apr 02, 2010 11:00 am Post subject: |
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Mike,
I was just looking for a ball park figure on a power system like that. thanks for the info. |
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Raymond Hearn
Joined: 02 Sep 2009
Posts: 17
Location: Washington, DC
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| Posted: Wed Apr 07, 2010 9:14 am Post subject: |
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All,
I appreciate all the great feedback. I have made some progress. Here's an update.
I installed one grounding rod and wired it to my electrical system with guidance from a local electrician. I'm happy to say that the RFI appears to have been vanquished!!!!! No more ESPN 980 playing soft and clear in the background. Hallelujah! Unfortunately, the buzz persists. I may be imagining this, but it seems like it is somewhat attenuated though. I don't hear the buzz if the preamp gain and headphone volume are set at reasonable levels. But when I crank them up to the extremes the buzz is unmistakable. And it still stops when I unplug the laptop from the electrical socket.
Using a ground lift adapter on the computer makes the buzz more intense. Go figure.
Prior to installing the ground rod I tried Mike's progressive circuit breaker test to try and isolate the circuit that was the source of the buzz. I shut off all the breakers except the one powering the recording studio and I still heard the buzz. So if the buzz has something to do with my houses wiring the problem is either on my recording studio's circuit or global to the entire wiring system. But I want to run the test again to confirm.
As for the possibility of the noise coming from the computer's power adapter... that's possible, the electrician mentioned it as a potential problem. However, I'm on my second Mac and I experienced the same buzz with both computers.
There's still the Mic cable as the possible problem, but it seems unlikely given that the buzz comes and goes depending on whether or not the computer is plugged into the electrical outlet.
Not sure what to do next, but I'm glad to be making progress with the help of all of you!
Thanks,
Raymond |
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glenspot
Contributor
Joined: 23 Jun 2008
Posts: 36
Location: Milwaukee, Wisconsin
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| Posted: Wed Apr 07, 2010 9:35 am Post subject: |
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A very non-technical solution......
Only run on battery when recording. Buy a second battery for standby if needed.
?
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Glen Pavlovich
www.glenpavlovich.com |
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Mike Sommer
A Hundred Dozen
Joined: 05 May 2008
Posts: 1222
Location: Boss Angeles
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| Posted: Thu Apr 08, 2010 9:23 pm Post subject: |
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It sounds like a Electro Magnetic Field (EMF) interference, i.e. a power supply is feeding noise back into the power supply. Note: I said a power supply, not necessarily the computer's power supply, it could be the M-Box's power supply. I'm guessing that you've used the same M-Box unit with all your computers; is your M-Box being powered from a FireWire or USB port, or from a 12-volt wall wart?
I'm wondering what would happen if you used a different interface? [Right now I'm going to point the finger at the interface. It's hard to believe every computer you've used is back-feeding noise]
For the price of a new XLR cable, it's worth trying it out. (Keep it a short run. Seek out a quad 4 cable if you can. )
Try plugin into another outlet. There are 3 lines that come into your home's service; one common (neutral) line and two hot lines (each are either 110 or 120). On the rows of breakers in your box, they alternate form one mainline to the other (two breakers joined together make up a 220 or 240 line). So if you can locate a line in your house that's on the opposite line that you are using now, you could possibly lose the hum. But not likely -but worth the try.
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The Blog:
http://voiceoveraudio.blogspot.com/
Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong. |
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Raymond Hearn
Joined: 02 Sep 2009
Posts: 17
Location: Washington, DC
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| Posted: Thu Apr 15, 2010 7:04 am Post subject: |
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I'm thrilled to report that the Quad 4 mic cable solved my problems!!! Not only did it banish the buzz/hum, but it also solved the RFI problem! I thought the ground rod took care of the RFI, but a couple days later it came back in full force. So I gave the mic cable a try and I was absolutely blown away by the immediate difference. Wish I would have tried that first! Thanks Mike. You're a genius!
Raymond |
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Mike Sommer
A Hundred Dozen
Joined: 05 May 2008
Posts: 1222
Location: Boss Angeles
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| Posted: Thu Apr 15, 2010 8:20 am Post subject: |
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| Raymond Hearn wrote: | | I'm thrilled to report that the Quad 4 mic cable solved my problems!!! Not only did it banish the buzz/hum, but it also solved the RFI problem! I thought the ground rod took care of the RFI, but a couple days later it came back in full force. So I gave the mic cable a try and I was absolutely blown away by the immediate difference. Wish I would have tried that first! Thanks Mike. You're a genius! |
And don't forget- an accused plagiarist too. EEEK! --- Better watch out!!! 
You're more than welcome.
Don't say I didn't tell ya in my first post. Monster cable is crap; a lot of hype at too much cost.
You can get Qaud 4 cable bulk at .50¢ a foot, grab some Neutrik connectors
and make your own cables for a fraction of the cost of pre-made cable.
Your ground poll probably did work. Like I said your soil needs to be able to
have a resistance of 5-ohms for effective RF mitigation. A copper clad poll
can not usually give that, unless your soil has a high mineral content. As we
move into summer the atmospherics are changing, and the signal got
stronger. "And the moon has move into New Moon Phase..... Kidding." This
stuff does get real crazy very fast. It's just important to work
backwards, and never assume, something is right just because. VERIFY.
Check and Verify again, and Verify again just to be sure.
But now you got clean audio and peace of mind with your new electrical
ground. And now everyone now knows more about grounding than most
electricians.
_________________
The Blog:
http://voiceoveraudio.blogspot.com/
Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong. |
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georgethetech
The Gates of Troy
Joined: 18 Mar 2007
Posts: 1878
Location: Topanga, CA
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| Posted: Fri Apr 16, 2010 10:38 pm Post subject: |
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I solved a noise problem today by simply removing an LCD monitor from the top of my client's Avalon 737. That's all...
Some RFI/EMF from the LCD's high-voltage back light power supply, I presume.
Never overlook the simple/free solutions first.
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If it sounds good, it is good.
George Whittam
GeorgeThe.Tech
424-226-8528
VOBS.TV Co-host
TheProAudioSuite.com Co-host
TriBooth.com Co-founder |
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