VO-BB - 19 YEARS OLD!

[juliaknippen]

Apologies for this basic question. This is a screenshot of me recording room-tone in Twisted Wave. Is the number at the top of the image my noise floor, or is it the number at the bottom? Or am I looking at the wrong thing entirely because that is also possible. Also, is this noise floor acceptable?

Many thanks!


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[FinMac]

Hi Julia,

Yes, the top number is your real noise floor. -63 dB is pretty good for a noise floor.

Watch this video by George Whittam to learn more about the subject...

http://www.youtube.com/watch?v=qAyUtNoT28A&sns=em
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www.scottsvoiceover.com - An American voice in Finland

"If you want to get to the top, you have to get off your bottom". (Unknown)

[DenaliDave]

I try not to rely on those numbers to terribly much in TW. They're a good "guide" or eyeball. What I like to do is just record 15 seconds or so of total silence, and then use the "analyze" tool.

The bottom number is RMS in real-time...I want to say the top number is the highest (loudest) within the last few seconds -- the "peak" so to speak. I know Logic X has this feature.

But to get a real clear and accurate picture of one's noise floor -- the recording of some reference noise floor samples and getting the RMS from that is probably more accurate.


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[Bish]

Note that the top number (the -63.1dB) is not a good guide unless the pre-amp input is set to record your voice at the "correct level". If you are set so that your voice recordings are coming in at your nominal level (say, between -3dB and -9dB) then that -63.1dB is a meaningful depiction of your noise floor.

It's all about the S/N (signal to noise) ratio... numbers in isolation can be easily misinterpreted.
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[FinMac]

Great point Bish! I assumed that recording was done at the level she normally records at, which was based on the assumption that it was a correct level.

2 too many assumptions
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www.scottsvoiceover.com - An American voice in Finland

"If you want to get to the top, you have to get off your bottom". (Unknown)

[juliaknippen]

Ha! Yes, this is the level I record at. The gain on my mixer is between 4 and 5:00. I imagine I could get that noise floor a lot quieter if I turned down the gain. I'm not THAT new at this

Thanks, everyone - this is very helpful. I'm going to scurry off and use the analyze feature.
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Her Voice Will Grow on You

[Ed Fisher]

To know your "noise floor" you would need to record something.
Normalize to 100%.
Then... what you have in the silence between words...

That's your "noise floor."
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[juliaknippen]

Thanks, Clutter - yeah, I watched George's youtube video and realized that was what I had to do. So now I'm slightly confused.

This is a screenshot of the analysis of the space between words of a recording normalized to zero. If I'm reading this correctly, my noise floor is -58.14.



This is a screenshot analyzing the normalized voice recording of the same file. Which of the numbers would tell me if I'm recording at the correct volume?



And finally, this is the analysis of straight room tone without any voice recording, which is recording at the same input level as the first two screenshots, but has not been normalized. Does this mean my -67.23 noise floor reading isn't real?



Just an FYI, George has helped me get this far, but now I'm experimenting with gain and placement of my 416, and I'm trying to teach myself to fish instead of ordering it from the master chef all the time
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Her Voice Will Grow on You

[Ed Fisher]

My above suggestion is based upon a post in this forum from Soundgun. Copied here: (since I can't figure out how to link to a specific message)

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PostPosted: 29 Jul 2013 08:37 pm

I measure noise floor thusly (right or wrong):
I get a 1 minute sample file of a script with some room tone from a client who wants a free evaluation.
First I check their peak level and note if it falls below -6dB or above -3dB.
Then I Normalize it to 0dB and note the peak dB level during the room tone. I find it exceedingly rare to see a reading fall below -60dB. I'll do the same thing after a steep slope HPF set at 80Hz to compare (it usually falls 10dB or more).

That's it.
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If it sounds good, it is good.

George Whittam
The "UNgineer"
Edge Studio, Director of Technology
VOBS.TV Co-host


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P.S. Make sure you "peak normalize" and don't use "average RMS."

I hope this helps.
However....
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"I reserve the right to be completely wrong."

[juliaknippen]

Ahhh, I see - I need to check the peak levels before I normalize.

Ok, I bumped up the gain a touch more to get my voice recording closer to between -3 and -6. Here's a screenshot of that, before normalization to zero:



Then, after normalizing to zero, the silence between words has a true peak value of -57.41. Not exactly ideal, but in 4 years is the lowest noise floor I've been able to achieve without using a hi-pass filter in post.

I can actually set the gain much lower to get the same peak levels when recording into my Rode-NT1A, giving me a lower noise floor, but George says the 416 has less reflection and sounds better.

Thanks for taking this educational journey with me!
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Her Voice Will Grow on You

[Lance Blair]

Throw another factor into the mix - the NT1-A has a much lower 'self-noise' than a 416. That Rode is one of the quietest mics available.
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[Bish]

Lance makes a good point regarding the relative performance of the different microphones. You can break down the noise in your signal chain as follows:

Microphone self noise: As has been noted, some mics are quieter than others. The CAD e100s is very quiet, the 416 is not excessively noisy, but it's far from a stellar performer in that department.
The pre-amp noise: The quality of the base components and the physical construction of the preamp will have a significant effect on the noise in the system. Some are quiet as church mice, but others will quietly hiss away while you pull hair out until you realize that buying a Behringer was never a good idea!
DAC: Again, the conversion of the signal to/from digital is subject to the quality of the components used.
Cables: There's nothing active to make noise, but every cable connection can be a source of noise (or signal degradation). Every place where there's a contact connection (plug and socket) is a barrier. Good quality cables with gold contacts mitigate this to a great extent. The other thing about cables is that they are great for picking up all sorts of stray signals. Hum from where they are getting too intimate with a power cable, RFI from almost anywhere.
Environment: One bad fluorescent tube or wall-wart transformer too near susceptible equipment will put noise/interference into the system.
Gaussian/Brownian noise: This is the inherent noise of the universe. Any wire or component that exists above absolute zero will generate this tiny amount of noise. I include it just for completeness!

The trick is to work out what you can fix, what you can't, and if it matters. I was talking to someone who was sending themselves absolutely crazy because the couldn't get this noise floor below -70dB. You can get yourself tied in a knot chasing numbers.... and to reiterate the George quote... "If it sounds good, it is good."

Sorry about the Janet & John, Noise 101 approach... It's what I do
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Smoke me a kipper... I'll be back for breakfast.
I will not feed the trolls... I will not feed the trolls... I will not feed the trolls... I will not feed the trolls.

[juliaknippen]

Bish, you never need to apologize for being a gentleman and a scholar

I'm definitely starting to see how one can become addicted to continuously tinkering with all the variables. In my case there are plenty.

The 416, in a shockmount in a small double-walled WhisperRoom (3.5x3.5) treated with panels and basetraps from ATS acoustics, making the square footage even smaller, is going directly into a Behringer Micromon MA400 (which is in the booth for headphone monitor controls), then into the main channel on a Mackie 802VLZ4, then the Mackie goes into my iMac via the Scarlett 2i2. I also have a Behringer UCA222 to get a mix-minus setup for Skype playback. There's also a talkback mic at my desk that goes into another channel on the mixer. Not to even mention the booth windows, the copy stand, the tiny table for my wireless keyboard and mouse, and my mounted ipad. I only have battery operated LED lights in the booth.

Can I have my audio nerd card now??
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www.juliaknippen.com
Her Voice Will Grow on You

[Bish]

Consider yourself to have a fully-paid-up membership to the VO-BB Audio Nerds club!

I've always had a soft-spot for the Mackie VLZ & Onyx stuff... it's quality gear at a good price-point. Up until not so long ago, I was using a VLZ3 on my input chain. It was superseded by the Audient iD22 which gives me the input flexibility I need. If I needed a small 2-in/2-out interface, I'd pick up the Mackie Onyx Blackjack... functionally the same as the Focusrite 2i2 and built like a brick-outhouse.

Tinkering is addictive... I have spent many a quite afternoon re-routing cables... just because I can
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Bish a.k.a. Bish
Smoke me a kipper... I'll be back for breakfast.
I will not feed the trolls... I will not feed the trolls... I will not feed the trolls... I will not feed the trolls.

[Kristin Lennox]

I have no idea if I'm doing this right in Audacity:

I recorded myself, plus lots of silence. I amplified the whole thing to -3.5 dB, normalized the whole thing, then highlighted the room tone, and checked the Plot Spectrum, which says:

Peak: -90.9 dB



That can't be right, can it? What am I doing wrong?
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