What would a reasonable noise floor target be

heymj wrote on 7/22/2005, 8:10 AM
I have been plagued by what to me seems like excessive noise during recording using vegas on my desktop(and also on a borrowed laptop using CUBASE). I am Firepod in both cases

My results are similar for each computer:
With the mic or line input gain is increased to something usable, the meters move off of infinite and sort of dance around -66 dB. Recordings of narration in a quiet room with this -66 dB stuff is aggravating to say the least. I added gate and noise reduction plugins, rendered the track and was able to obtain fair results, but I am dissatisfied with the software only solution.

In an earlier thread, I found article http://www.sonymediasoftware.com/forums/ShowMessage.asp?MessageID=242420
which suggests ground loops can contribute to this noise floor. I can look further into this.

Do others achieve quieter recordings? I know that rooms are noisy but I did this at 2am with the appliances all turned off. Direct monitoring via headphones through the Firepod == quiet, but software monitoring (and playback of the recorded track) sounds like a few fans are running along with the narration. BLECH.

Digital is supposed to be quiet - I want to get the noise floor down to -80 dB at least. Should this be possible?

Are there other things I should be looking for besides ground loops? I have a furman power conditioner that I could start using - I'm not sure if it will solve the problem.

BTW I also noticed an alarming amount of noise when the laptop power supply was plugged in. I don't think I can use the laptop as a result of that.

Any input would be appreciated - thanks!

Comments

James Young wrote on 7/22/2005, 8:50 AM
mics, cables, preamps, converters, your audio interface... these can also contribute to noise, especially if they are on the cheaper side. What mic are you using?

Some people have said running on battaries makes things quiter - never tried it myself.

You can easily get -80dbFS, just turn down the master fader!!! :)

OK, probably not the answer you were looking for, obviously, but a noise floor that low will be hard to get in your circumstances, and alot of recordings that do go that low also have a very low average loudness, or peak-to-floor ratio.

Dither can also make alot of noise!!
heymj wrote on 7/22/2005, 10:17 AM
Mics:
* AT-825 stereo mic
* Rode NT1A
* AKG C-747, C1000S, C3000B
* Behringer B2 Pro, B5

Preamps:
* Presonus Firepod
* M-Audio Delta-66 PCI interface with Omni I/O module

Mixer:
* Behringer MX3242X

Cabling:
* All balanced inputs with heavy belden cabling and neutrik connectors

Interfaces:
* DI boxes used for connecting other stuff like my CD player or FM tuner to the Firepod/Delta 66..

I don't think I'm using cheap stuff. Do any others care to post their noise floors? I'd be real curious to hear other experiences.

Yes definitely if I reduce the input gain I get less noise - It is an interesting excercise. I'll start with the grounding scheme - I have to move the rig to a location tomorrow morning. We'll see what happens.
rraud wrote on 7/22/2005, 10:48 AM
-66dBFS with a pre-amp and a mic connected including amb room tone is good. Pro reel-to-reel recorders in repro only had a noise floor of -55-60dB without anything cocnnected.
Perhaps the noise your hearing is somewhere is the monitor chain.
Do a spectrum annalisys to see any freq. spikes. A ground loop would be around 60Hz (USA) with some harmonics
farss wrote on 7/22/2005, 4:54 PM
With just the NT1A into the Firepod you should be able to do pretty good, the NT1A is rated as the worlds quietest mic at 5dBA and that's very quiet.
Simply way to find out where the noise is oming from, plug in mic, turn gain up to useable level and smother the mic with some acoustic foam, if noise goes down then it's in the room, simple really.
I use the NT1A into Firewire 410, don't imagine there's a huge difference between that and the Firepod in terms of preamp quality and I can get about -75dB noise floor but all of that is ambient noise.

Getting a good amount of sound into the mic will help a lot, having the mics too far from the source = more gain = more noise, plus the ambient to wanted signal ratio is getting worse, just watch how you place the NT1A, it's got lots of bottom end and pops can be a problem with some speakers and singers, popper stopper will help.

Bob.
musicvid10 wrote on 7/28/2005, 4:23 PM
Looking at your equipment list, the weakest link may be your Behringer mixer. Although many claim the newer models are quieter, they all seem noisy to me. Borrow a Mackie, a high end M-Audio, or search these forums for other suggestions, and I bet you'll drop the floor a bit more.

See what your Behringer puts into your soundcard with no sources plugged in and the gains at different levels.
gunnywolf wrote on 8/2/2005, 6:39 AM
I have recorded around five professional storyteller CD in the last few months so I understand the importance of a clean sound for narrative only tracks. I have gotten amazing results but I cant tell you exactly why. Here are some on the thing I did.

For outside noise: Sound proof the room. You can get materials such as homosoap at home depot or simply use insulation sheets. Cut these to fit all doors and windows and use weather stripping to seal it up. Also, I put curtains and blankets up on all the walls. This sounds better than foam for narative. Also you can double rug the floor. This dampens the sound as well. Put a towel over the back of the computer to dampen the fan. It is amazing how importance the "tone" of the room is for voice only. Unplug and uncable everything else you are not using during the recording. Keep the system as simple as possible. make sure the AC, refrigerator and any other appliance is off. DONT use compresion. It brings up noise volume. Get an amazing pre-amp.

Hope this is helpful.