Acceptable noise floor?

Posted: Fri Jan 06, 2006 1:49 pm

I'm not sure this is a mastering question, but I'd like some feedback from mastering experts if possible. I'm recording solo acoustic guitar (think Alex de Grassi, or Leo Kottke, or...) in my home studio. I've been doing a lot of work on reducing noise and have made a lot of progress, but I'm curious how much further I need to go. If you got a recording to master that was 0 DB peak, and had room noise (a little humm-like sound at 100 Hz and below, and some broadband hiss across the board) at -65 db RMS in a section of "silence", would you be concerned? What levels of noise during "silence" are typical for a quality recording before mastering?

Doug

Posted: Fri Jan 06, 2006 1:58 pm

As we age..we have different levels of acceptability. I am a older guy..-65 dont bother me

Frankly, -72 is about where I consider the threshold point to be.

This is considering I am listening with peaks of 100dB , this level will be at or about 28dB ..whch is below what I can hear unless I really strain to hear it.
At a 90dB playback level..I am not going to hear -65dB

At levels above 100dB, it is too loud and noise from other equipment (preamps, amplifiers and the like) will be audible in many cases.

If my meters during recording..are above -65..I look for the problem, track it down and see what I can do about it.
I see others' mixes all the time and -65 is nothing to be very concerned about.

In mastering, I can drop your floor to -75 with NO problem.

Posted: Fri Jan 06, 2006 2:42 pm

Good point, Bill..... I was wondering while reading this - how critical is anything below -65 during the music, anyway? Will anyone really hear it on today's mp3 players and "on the go" world of music listening?

Of course, good mastering can get rid of it in between tracks, during fadeouts and under "exposed" areas of music - where the noise would be more obvious. But it's good cause to wonder, esp if we're talking about audiophile listening, as rare as that seems to be.

With all these overly crunched CDs that are out now, it's still gratifying to read someone concerned with the noise floor, however moot it may be becoming. So many songs' waveforms now look like a two-by-four in the DAW's window, I get disgusted with each new CD I open and listen to: no dynamic range left, and nothing but LOUD, rude music that wears thin after 5 minutes of listening.

That's why I like "live" acoustic music, in a club, hall or even in the studio, where a little ambience remains between tracks, to tell you that there's something "Real" going on, and the noise (such as it is) is just an indicator that there's real, living, breathing people in the room between the musical moments.

Posted: Fri Jan 06, 2006 2:54 pm

With his genre of music, I would hate to see his art pushed up to the point where even more than 2 or 3 peaks would go past -1dB. Organic sound and recordings can sound very artificial if overcompressed. You want just enough compression to hear the decays and harmonics of the strings but not so much to kill the "wood" and "feel" of the performances.

Posted: Fri Jan 06, 2006 4:30 pm

Heck, -65dBFS is a great noise floor figure. For soloists, that's just fine. For full ensembles, you can go a bit higher even (-55 or so).

Bear in mind, the best noise reduction algorithm in the world exists in the human ear - we're simply able to tune most of that stuff out, and do by nature. However, bear in mind, one of the most powerful measurement instruments in the world is the human ear too! So, too much noise-reduction processing and the artifacts will become readily apparent. The bad news is, if you've been layering them on little bit by little bit, you'll have a hard time hearing the artifacts as you become accustomed to them.

For on-location, live classical recordings, I shoot for a minimum of -50 - -55dBFS noise floor while tracking. Bear in mind, during the mastering phase, I can get it better by using HPFs during quiet flute solos and the likes.

For a solo classical guitar recording I'm working on right now, I'm typically getting -72 - -75 dBFS. However, I rarely have a peak reach over -3dBFS (hard strums - finger of course, and large, built-up sections are about it). With guitar, I feel that transients are VERY obvious and so therefore is squashing them with a limiter. Some of what gives solo guitar its impace IS the transient nature.

However, to answer your original question - you are doing just fine with -65dBFS.

J.

Posted: Fri Jan 06, 2006 5:32 pm

Thanks everyone. Good to know I'm in the ballpark. I started *much* higher, but after killing the computer noise, the light dimmers and assorted other things, it's sounding pretty good, but wasn't sure what the standard was. The low frequency hum is annoying to me, just because I can't quite locate it. Not that I can hear it when the guitar's present, but if I listen to the recorded "silence" and crank it up, it's there. I pretty much decided it's the road noise that tends to be all around in my area. My studio is one room, so there's some sound from the various electronics, but it seems to be pretty minimal.

I thought I was probably getting close when I traced down a new rumble last night to my cat purring across the room...

Doug

Posted: Fri Jan 06, 2006 5:36 pm

Quote:

I thought I was probably getting close when I traced down a new rumble last night to my cat purring across the room...

LOL!

I'd say you have reached an acceptable goal.

This topic sponsored by: