VO-BB - 20 YEARS OLD!

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

Here is a short sound sample with a strange high-pitched whine I've been getting lately....

http://WWW.ROBELLIS.INFO/images/Rob_Ellis_hum_sample.mp3

It usually doesn't start until I've been recording for about 15 minutes. Shows up on both of my computers, and on recordings with and without my pre-amp. So I'm beginning to think it may be something in my electrical wiring, though this hasn't been a problem in the past---oh yeah, lighting in booth is LED.

Any insights are , as always, appreciated!

Hestoft · Contributor Joined: 11 Jul 2010 Posts: 39

What type of A/D converter are you using? Does the whine show up EVERY time you record, always after fifteen minutes, or is is less regular? If you move the mic or cable, does it increase of decrease?

It is at such a high frequency it doesn't sound like florescent issues I have had. Perhaps more of an RF interference issue? Do any fans or ventilation kick on after fifteen minutes of recording?
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Mike Sommer · Posted: Wed Aug 04, 2010 7:46 pm Post subject:

Audio Chain please-- what's the mic? Is it the 416?

Do some detective work, and let's see what happens.
Try a different mic. Try different mic and preamp.

First thoughts are:
Sounds like a bad capacitor. Or the capsule needs cleaning.
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georgethetech · Posted: Wed Aug 04, 2010 10:26 pm Post subject:

Sounds to me like CPU or LCD monitor CFL backlighting interference.
Unplug your monitor or ground lift the monitor and/or computer and see if it goes away. This kind of thing is very frustrating to debug sometimes. Embarrassed

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Lance Blair · M&M Joined: 03 Jun 2007 Posts: 2281 Location: Atlanta

After the words "And there's no cure" there's a nice RF crackle to go with the whine. Or is it RF? What do people think?
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Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

I haven't been extremely methodical, but it has shown up with all of my mics, with and without my preamp, with both my interfaces, and with more than one mic cable.

Hestoft · Contributor Joined: 11 Jul 2010 Posts: 39

Is there anything else in the room with you? Computer, phone, iPad, anything electronic?

It is the "starts after fifteen minutes of recording" part of it that gets me thinking that something is either kicking in after that time (computer fan) or something is getting to warm and a component is complaining. RF noise should be more constant on the one hand, and very with different mics or cables or placement.

I did notice that my monitors (a Dell and a Samsung) both emit a very high frequency whine from the top, and had to move my 416 away from them to avoid the problem...
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Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

I'm in a vocal booth, and the only possible gadget inside is an LED light.

I tried plugging my computer into the wall outlet instead of the surge protector bank of outlets that I normally use.

We'll see if that does any good.

Mike Sommer · Posted: Thu Aug 05, 2010 9:50 am Post subject:

Rob

What computer are you using, tell us what interface and any other device you have in the audio chain.

If it was RF interference it would either be notably intermittent or be detected immediately from a device like a monitor.

Like I said before it sounds like a capacitor failing, or, if you are using a laptop, the power supply or USB port of the computer is causing interference.

If you are using a USB interface, try switching ports and or cables.

I doubt if it is a ground problem--- but are you using an AC device?
To be sure it is not a ground problem, shut down the house at the service panel, and use only the circuit that powers the computer and audio chain, to see if the problem persist.
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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.

KaseyKruz · Club 300 Joined: 18 Apr 2008 Posts: 336 Location: Michigan

Sounded like USB noise to me.
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Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

Both my interfaces are firewire

Signal chain= M930>AValon 737> Apogee Duet> DAW

So far today the noise hasn't been a problem. But I haven't been doing a lot of recording. That's the tricky thing. This isn't constant. It has only cropped up intermittently the last few days, and only after I have been recording continually for at least 5-10 minutes.

Hestoft · Contributor Joined: 11 Jul 2010 Posts: 39

A tube in the Avlon gets warm and starts to exhibit noise? The Mac Mini gets hot and a fan kicks in and/or other components overheat and cause noise? Maybe try a defrag of the Mac hard drive. Perhaps it whigs out after fifteen minutes of recording?
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Mike Sommer · Posted: Thu Aug 05, 2010 10:08 pm Post subject:

Yes Rob, by the way you described the noise starting after 15 minutes it makes total sense that the tube in the Avalon is starting to crap out. Which is also why I suggested that a capacitor is going too. Both take time to warm up, (actually the Capacitor need to "reform") and 15 to 20 minutes are about the magic numbers for this procedure.

First thing you can do is unplug the Avalon, open the case and remove the tube, blow out any dust -while your at it. Look at the tube pins and make sure they clean and shiny. And reinstall the tube.
This may or may not do anything to help, but it's a start, then get a new tube; get two new tubes. it's always good to have a back up.

If you have another preamp try that and see if the noise persists. It does then it's time to look at the interface.
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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.

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

I'm pretty sure that this has shown up both through the Avalon and the Apogee Duet, though I may do more systematic re-test to be sure.

It almost seems as if the noise shows up not based on the time the pre-amp has been on, but based on how much actual use the mic is getting. Though I could be wrong

Plus, I just put new tubes in the Avalon about 2 weeks ago.

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

Starting to look like it may have the printer cable laying right on top of the DAW power cable. I moved it and so far so good. Will keep you posted.