VO-BB - 20 YEARS OLD!

[cyclometh]

So I've been doing a "noise cleaning" of my recording environment- I posted about it on my blog with "before" and "after" recordings (see the end of this post for the link if you're interested).

You can hear the difference between the "before" and "after" quite easily:

http://www.cyclometh.com/wp/wp-content/uploads/2010/08/backgroundnoise_before.mp3

http://www.cyclometh.com/wp/wp-content/uploads/2010/08/backgroundnoise_after.mp3

What I'm curious about is the remaining noise in the "after" MP3. I use a Cascade M20u large-diaphraghm condenser patched through a Behringer X1204 mixer to the USB input on my PC. The noise isn't present on the monitor, but only after recording, which implies to me it's coming from the PC itself.

Two questions: Is my supposition correct, and if so, how can I eliminate this issue? With an external sound interface like an M-Box?

Blog entry: http://www.cyclometh.com/index.php/2010/08/the-sound-of-silence/
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Corey "Vox Man" Snow
http://voxman.net

[Mike Sommer]

The pictures on you blog post tells the story of you residual noise.

Though you've moved the computer out of the room, you now have two big holes that allow the noise from the other room in. In some other threads, I've mentioned that a 1-inch hole is equal to having the door open. What happens is that some frequencies can actually be amplified. What you are hearing in your second file is the computer in the other room.

Personally the two pipes are overkill, you could have possibly gotten away with one. But to help mitigate the transfer of sound from one room to another you need to create a sort of "Sound Trap". You can do this by placing 90° elbows on each side of the wall. With large holes like this, once I've pulled my wires, I tightly pack insulation inside; you might be able to place a rubber cap on the ends too.

To explain what's also happening with the noise in the room, is that the room is taking the frequencies that are coming through the holes, and or any other sounds that may be going on, and they are being amplified by the room itself. This is what I call the guitar effect. A tensioned guitar sting by itself will make noise. But place it on a box and the noise is amplified. Our rooms/studios are nothing more than boxes full of air, the same is true with a guitar or a violin, these are nothing more than tuned boxes. Once set in motion these boxes vibrate/resonate and enhance/amplify frequencies.

So besides eliminating everything that makes noise, you need to kill the resonance of the room; and we do this with rigid insulation on the walls.
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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.

[cyclometh]

Thanks for the response. I wanted the two pipes for a few reasons, so that was a deliberate choice. I appreciate the tips and I'll see what I can do about implementing them.

Got a lot of work to do to get this space where I want it. I think I'll also be creating a recording booth.
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Corey "Vox Man" Snow
http://voxman.net

[cyclometh]

I did some more testing and discovered that even with the mixer and so forth turned off I'm still picking up a bit of noise. Essentially, when recording with no inputs I'm getting a hiss that must be coming from the PC itself.

So it's good I've got an Mbox on my "to get" list.
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Corey "Vox Man" Snow
http://voxman.net

[georgethetech]

Mbox because you have to use Pro Tools?
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[cyclometh]

[Jeffrey Kafer]

I've had great success with an ART tube USB interface. My $99 pre has recorded many many audiobooks and elearning modules. And with a noise floor at -65db, I can't complain.
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Jeff
http://JeffreyKafer.com
Voice-overload Web comic: http://voice-overload.com

[cyclometh]

Looks like my noise floor is about -50 db right now with my mixer and mic.
_________________
Corey "Vox Man" Snow
http://voxman.net

[cyclometh]

OK, I did even MORE testing.

Here's what I discovered: The default Windows USB drivers were adding a lot of noise. Replacing them with the ASIO drivers from the Behringer web site improved the noise floor thus:

* With the mic and mixer off: -82 db.
* With the mic and mixer on, but silence in the room: - 73 db

These are approximations, but should be fairly close.

With the updated drivers the signal is much cooler overall. Even with the gain fairly high I'm not getting a huge amount of signal into the PC... so that's where a preamp will probably come in next.

I'm actually very pleased to get those results with what I've got set up. I'll post more results as I have them, and thank you all for the input thus far.
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Corey "Vox Man" Snow
http://voxman.net

[jsgilbert]

It looks like you have a gamer PC. One thing I would suggest if you aren't already doing this, is to make sure to turn off all virus and trojan checkers, disconnect from the internet and any networks, disable everything in your startup except for what you absolutely need.

The noise floor is one thing, but all of these other things can add audible glitches, or affect things on sampling, which can ce=reate issues later on when a client tries to process your files. I also recommend that everyone record at 24 bit, making sure to leave a decent amount of headroom, and then to adjust volume afterwards and adjusting bit rate to 16 bit before saving your final output file, especially if you do any processing. Most of the plugins will aprreciate working with 24 bits.

You'll generally also find better results having a 2 drive system where your program files are on the boot drive and scratch and final output are on a speedy second drive. And with ram relatively inexpensive these days, one should have as much ram as practically possible. Windows XP has a $ gig maximum ( well actually 3 3/4 max, but you'll need to install 4 gigs)

While this may ro may not pertain to the matter here in this thread, perhaps readers will find this applicable to their battles with getting good sound.
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