VO-BB - 20 YEARS OLD!

[captain54]

Some discussions a ways back with Mike Sommer revolved around bringing down the SPL readings in a recording space to a anywhere between 25db - 30db.. I've managed to have my levels around the 30dbC range.. never a complaint from a client..

What's the difference between calculating the Noise Floor, or room tone, and the SPL level of a room? Is the Noise floor, the signal recorded w/o the VO? According to my research, that level should be around -60db

My question is, how does my 30dbc reading translate to the Noise Floor reading? if not, how do I calculate the Noise floor? Is the SAVOA 40db standard the Noise Floor, or the SPL?

[Jason Huggins]

So here is a crack at it.

You are talking about a couple different measurements (obviously).

- dbc is a measurement (and logarithmic calculation) of signal relative to carrier. Making it a positive number if the carrier is 0.

- dbspl is a measurement of the actual Sound Pressure Level (SPL) and is quite different from measurements that are based on an electrical reference.

- dbfs (full spectrum) is a measure relative to digital capability (16-bit is -96 to 96dbfs)

dbspl is an absolute measurement, where the other two are relative to a reference.

SAVOA standard is actual -40dbfs, which is nowhere near what a professional studio should be at. You should be shooting for -70dbfs (optimally).

Room tone is simply a recorded silence of your recording space to be used as "silence" instead of adding actual silence (because silence would sound bad).

Noise floor is, as you said, the level of "silence" in any recording. Noise floor should be measured at normal recording levels, and will change depending on how you use your gear.

SPL is typically used to measure sound, not the absence of sound. It is better to measure your noise floor in dbfs, shooting for -70db (though that isn't the easiest thing to attain depending on your space). -60db is usually acceptable. Much higher and your noise floor will start being very present in your recordings.

Hope that helps.

[captain54]

If u are trying to find the quietest place in the house to set up shop, the dbc measurement would seem more useful than the dbfs measurement, correct?

[Jason Huggins]

Honestly, it would not make a difference as long as you use the same measure and gain settings in all locations.

[Edwino]

So how do you measure your noise floor? This is what I don´t understand because if you increase your gain the floor surely goes up. Is there a standard gain measurement? What are normal recording levels?

[Jason Huggins]

I would say, normal recording levels would be average peaks at -6db with spikes no greater than -3db.

Yes, noise floor goes up as gain is increased, making it a slightly difficult measurement to really grasp. I would have an INCREDIBLE noise floor if I recorded so my audio peaked at -24db, but the end result would not be pretty.

There is not a standard gain measurement, because each preamp is different. They all have similar capabilities (like amplifying the signal by a certain amount) but each one has much different electronics inside. This means that the same mic, with the same interface, and different preamp can have a much different output when set at 0 on the gain (0 being no increase or decrease in gain).

Because of the differences, you have to set the appropriate levels on the equipment, then set the output level to the "recording level."

[georgethetech]

Noise floor is most important as that is what "goes to tape", and is what the listener will hear during playback. I measure it by recording room tone, then some scripted material at good modulation, peaking -6dB or so. Then, I Normalize the whole thing to 0dB, and check the PEAK level reading while playing back the room tone. Whatever the meter shows me is the noise floor. Sometimes I'll high pass the room tone at 80Hz or so and marvel at the significant drop in level, since a good deal of some room tone issues are very low in frequency.
_________________
If it sounds good, it is good.
George Whittam
GeorgeThe.Tech
424-226-8528
VOBS.TV Co-host
TheProAudioSuite.com Co-host
TriBooth.com Co-founder

[captain54]

So my dbC reading was around 30 .. Twisted Wave showed dbfs to be -55 when recording with a small shotgun on a boom at the desk, and -59 when recording away from the desk at a stand. The difference being the small shotgun was picking up the oh so slight hum from the Mac mini at the desk

As George pointed out, a high pass @ 70hz knocked another -5dbfs off the previous readings.. so with the low pass the desk reading on the shotgun was
-60dbfs, and the reading on the mic away from the desk was about -65dbfs.. interesting...

[Jason Huggins]

Looks like you're in pretty good shape then. Now that you know where your levels are, I'd suggest forgetting about it unless you start to notice noise (as in broken gear). Noise floor perfection is another one of those time leeches.

[captain54]

thanks Jason.. yes,... I'm moving in a few months and starting a new space all over again so I'll be back to square one shortly, saying goodbye to my nice quiet treated room with no booth... Good Lord..

[georgethetech]

Captain:
I bet if you hold your dB meter at the same position as your microphone while reading, you'd come up with a reading avg peak around 90dB.
Let me know if I'm right.
_________________
If it sounds good, it is good.
George Whittam
GeorgeThe.Tech
424-226-8528
VOBS.TV Co-host
TheProAudioSuite.com Co-host
TriBooth.com Co-founder

[captain54]

a normal read was between 75-80 dbC, and if I got a little exciteable it tickled 90dbc, yes..