Electrical interference on laptop recordings

Richard Durrer · From: Alberta, Canada

I am currently using a Dell laptop and Reaper to record sermons at our Cowboy Church. I feed a stereo 1/4 inch signal from the board mains to a headphone amp, then out to the laptop. I have noticed lately that I am getting a high pitched whistle on my recordings now. I can also hear it in the wireless headphones. The whistle disappears when I unplug the laptop from the power plug. The brick is still plugged in though. Someone from a sound forum suggested I run the signal thru a DI box to isolate the interference. However it does not make much difference. The interference is still noticable. Any suggestions?
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1999 Carter D10 (9x8),Digitech RP150,Hilton Volume Pedal,Roland Cube 80XL,Nashville 112,BJS Bar

Andy Sandoval · From: Bakersfield, California, USA

Have you tried a ground lifter (three prong to two prong adaptor) on the laptop power supply cord? I had a similar problem with my laptop and it worked for me.

Richard Durrer · From: Alberta, Canada

I have not tried the two prong adapter. Am I not putting myself at risk by doing this? There have been several topics suggesting that this approach may be dangerous.
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1999 Carter D10 (9x8),Digitech RP150,Hilton Volume Pedal,Roland Cube 80XL,Nashville 112,BJS Bar

Andy Sandoval · From: Bakersfield, California, USA

Well, you can't live forever. Just kiddin, Winking

be sure and post how you remedy the problem.

Ken Metcalf · From: San Antonio Texas USA

I had the same/similar prob.
Went down to Guitar Center Music store with my lap top and tried expensive power conditioners etc.
the only one that worked was a Hum-X that goes on the 110V power plug.
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Little Walter PF-89.
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Bent Romnes · From: London,Ontario, Canada

Rich, I hope you get to try what we discussed on Skype last night. Let us know the results here. It would be interesting to find out about this.
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Karlis Abolins · From: (near) Seattle, WA, USA

Richard,

Your best solution to this issue may be to use an old desktop pc that you can leave in the church for this purpose. I spent a couple of years chasing this problem and ended up giving the laptop to my wife and buying a small pc that I dedicate to music. No more interference.

Karlis

Richard Durrer · From: Alberta, Canada

Thanks to all for your comments. I can't use a desktop since I update our website with the recordings on the laptop. The church space is actually a large rented convention centre and we tear down every night. All the equipment has to fit into several large cabinets. I use a Peavey 32FX board that has a USB output. I am going to try that option into Reaper on Tuesday night. I will post the results. Rich.
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1999 Carter D10 (9x8),Digitech RP150,Hilton Volume Pedal,Roland Cube 80XL,Nashville 112,BJS Bar

John Roche · From: England

Here is a program that will stop all noise on your computer, $30 for the full version, down a trial version free, I have been using it for a few years now
great program..
http://www.softpedia.com/get/Multimedia/Audio/Other-AUDIO-Tools/No-Noise.shtml

David Collins · From: Madison, North Carolina, USA

Richard, went through the same thing with my dell. It is as simple as lifting the ground prong on the power plug. A simple 3 prong to two prong adapter from any hardware store or department store will do the trick.

Did on mine. Keep it in the bag with the laptop at all times!
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David Collins
www.chjoyce.com

winston · From: Frankfort, Kentucky 40601

Light dimmers cause noise problems in sound equipment. I agree with andy and david, use a ground lift connector for 30 cents and it will solve your problem. I would recommend using the adaptors on all you sound equipment and your computer. The late Jeff Newman taught me that trick. He said that years ago at the Opry that is what they did to eliminate ac noise from the amps. I have been using them for years and have never had a problem. winston may

Jon Moen · From: Canada

It would be safer to leave the power ground as it is intended, and put a ground lift on the audio cable.

John Roche · From: England

Has anyone tried the program I posted yet?

Richard Durrer · From: Alberta, Canada

Hi Folks. Since I only have access to the sound system on Tuesdays, for a limited time before showtime, I have not tried the software solution. I did try the USB connection to the mixer, but could not get any sound thru to the mixer. Reaper did recognize the Peavey mixer, and I chose that setting but no go. I did not change the setting within Windows. That was probably my mistake. I will attempt it again tomorrow (Tuesday). I may opt for the Behringer Hum destroyer with the integral ground lift etc. (Behringer HD400-2 Channel Hum Destroyer - HD400 $38.99 CDN). Rich.
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1999 Carter D10 (9x8),Digitech RP150,Hilton Volume Pedal,Roland Cube 80XL,Nashville 112,BJS Bar

John Roche · From: England

a screenshot of no noise.

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Kevin Rose · From: Georgia, USA

Finding the source of the noise and eliminating it is always preferable to using software. I do a lot of location work, ground lifts, transformer isolation and all manner of tricks come into the game. I do know a lot of laptops have PSU issues and require ground lifting or some sort of isolation between console and input.

The problem may also be impedance related.

So hard to tell from here.

Bill Terry · From: Bastrop, TX

Richard,
Our church uses the same Peavey mixer with the USB port. We just record the service to a USB memory stick and then transfer the result MP3 to a computer for editing, trimming or whatever. Ultimately it ends up as a webcast on the webpage I think..

Are you turning on the 'USB record' feature at the Peavey Mixer? It's under the Util menu if I remember correctly. This works well for us, although to my ears the MP3 audio is a bit colored.
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Richard Durrer · From: Alberta, Canada

Well- here's an update re: the "noise". I have tried the USB from the Peavey mixer again. Everything was connected and installed correctly on the laptop. The record light was lighted in the on position on the board: still no sound at the laptop. It appears I have may have to do a firmware upgrade on the board. I did install the software progam "No noise" and noticed no difference.

Now, to back up a moment, originally the Dell had a two prong plug from the power supply. When the power supply failed I replaced it with a 3 prong Dell power pack. That is when the problem first appeared. I have since replaced that power pack with another, also a 3 prong plug. VOILA. The recording is now quiet again.

So, I will leave it alone for awhile and keep monitoring the situation. Thanks to all for your suggestions. Rich.
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1999 Carter D10 (9x8),Digitech RP150,Hilton Volume Pedal,Roland Cube 80XL,Nashville 112,BJS Bar

John Roche · From: England

[quote]I did install the software progam "No noise" and noticed no difference.

Did you turn it on?

Richard Durrer · From: Alberta, Canada

John: Yes, I absolutely turned it on. I checked the sound before and after: no difference.

In addition, I checked for noise with the new power pack plugged into the laptop. Then with the power unplugged from the laptop. Then with the power unplugged from the AC source. It all sounded the same thru the wireless headphones. Then at home I checked what was recorded. There was no hiss, etc, like I had before. I concluded it must be the new power pack that solved it.
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1999 Carter D10 (9x8),Digitech RP150,Hilton Volume Pedal,Roland Cube 80XL,Nashville 112,BJS Bar

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