Input level "noise" of -72dbfs?

[iboersma]

Hi,

I have a Presonus BlueTube pre-amp and a Presonus Firebox dig. interface that are both hooked up to my Toshiba Satellite laptop. I'm new to the world of recording so I wanted to check with you all to see if getting nominal (read: resting) input levels in my DAW (Adobe Audition) of around -72dbfs is normal with this setup.

I have the pre-amp's tube drive set to OFF and I have the pre-amp gain set at about 90%. I have the Firebox's mic 1 gain set to about 50%. The Firebox Mixer has the Mic 1 input set to about -12db.

Is it normal in a recording environment to get this base "noise" at or around -72dbfs? I'm recording in a walk-in closet (don't laugh) with relatively good acoustics and very little ambient noise, so I'm assuming this noise is due to something in my setup. I've also moved my laptop outside of the room where I record and I get the same levels.

So - in summary, my setup is like this: Mic (Shure SM7b dynamic) >> Pre-amp (Mic 1 XLR) >> Firebox (Mic 1 using XLR input) >> Laptop (using 6pin to 4pin firewire cable) >> Adobe Audition

I've also tried using the Input 3/4 on the Firebox with a 1/4" adapter on my XLR cable (thus bypassing the pre-amp altogether) but I get the same base noise.

Any ideas? Or is this -72dbfs "normal" for recording voice tracks?

Thanks,

Ian

 

[Rokket]

There is always going to be some noise. Even in the high dollars stuff pro studios use. You will get hiss or hum from your mics, your cables, pre amps, everything. If it's that low, it won't be audible in your recordings. You can lower it by making sure that all your cables are shielded, and that your equipment is plugged into the same source, and some other tips that people can offer you.


But seriously, that's pretty low considering it's home recording.

 

[iboersma]

There is always going to be some noise. Even in the high dollars stuff pro studios use. You will get hiss or hum from your mics, your cables, pre amps, everything. If it's that low, it won't be audible in your recordings. You can lower it by making sure that all your cables are shielded, and that your equipment is plugged into the same source, and some other tips that people can offer you.


But seriously, that's pretty low considering it's home recording.

That's good to know. I'm using Monster Standard 100 cables, so shielding should be acceptable for those.

The sound I get when I play the track back is a bit like the sound I remember getting when you turned on a tape recorder with headphones, though not as loud. I have an audition for a TV documentary coming up and I don't want the noise to detract from my voice in any way....

Audition allows me to profile the noise and then remove it from the track, so I'm wondering if that might be a good idea before sending my voice tracks out, or if just leaving the noise in there is OK.

Thanks again,

Ian

 

[mshilarious]

Any ideas? Or is this -72dbfs "normal" for recording voice tracks?

That's what I suspected would happen, and mentioned in your other thread: what you picked up in gain, you gave back in noise. Thus your dynamic range is 72dB. I recall you were peaking at -12dBFS before; what is your noise floor using only the Firebox?

 

[iboersma]

That's what I suspected would happen, and mentioned in your other thread: what you picked up in gain, you gave back in noise. Thus your dynamic range is 72dB. I recall you were peaking at -12dBFS before; what is your noise floor using only the Firebox?

Hey,

I'm not sure what my noise floor is with just the Firebox and won't be able to check that until later this afternoon as I'm at work right now. But comparing that to my setup with the Pre-amp in front is a great idea.

You mentioned as well that you thought a peak of -12dbfs should be sufficient for doing voice, no? I guess if I find that I have less noise without the pre-amp, and -12dbfs peak is acceptable, I may have to go with that setup.

In your opinion, is this -72dbfs acceptable for voice tracks? Would editing it out via noise profiling be a good or bad idea?

I'll update this thread later today with my experience taking the pre-amp out of the loop and let you know.

Thanks again,

Ian

 

[iboersma]

That's what I suspected would happen, and mentioned in your other thread: what you picked up in gain, you gave back in noise. Thus your dynamic range is 72dB. I recall you were peaking at -12dBFS before; what is your noise floor using only the Firebox?

One other thing - I did check the noise floor when I bypassed the Firebox's on-board pre-amps by using a 1/4" adapter on my XLR cable and then plugging this into the INPUT 3/4 on the Firebox (rather than MIC 1) and it seemed that this didn't make any difference.

I may also try this using my desktop just to see if that makes any difference whatsoever.

 

[Blue Bear Sound]

-72dBFS is pretty damn low... I wouldn't have a cow over it if I were you!

 

[iboersma]

-72dBFS is pretty damn low... I wouldn't have a cow over it if I were you!

Would you recommend editing that noise out of the final recording or just leave it in? Again, keep in mind that I know voiceovers, but I'm a total beginner when it comes to the technology/recording side of things...

Thanks,

Ian

 

[gordone]

Damn, -72 is really good! I have a Soundelux U97 going into a Great River MP2 into my Delta 44 (set at +4), all balanced connections. With the GR's gain set at 50%, I get levels at around -40!!!
I would recommend not sending the output of your BlueTube into the Mic pre of the Firebox. Go mic->pre->line input of PC interface.

The important question, is how does it sound?

 

[iboersma]

Damn, -72 is really good! I have a Soundelux U97 going into a Great River MP2 into my Delta 44 (set at +4), all balanced connections. With the GR's gain set at 50%, I get levels at around -40!!!
I would recommend not sending the output of your BlueTube into the Mic pre of the Firebox. Go mic->pre->line input of PC interface.

The important question, is how does it sound?

I'm heartened to know that I'm at least not out of the ballpark in terms of base noise.

How does it sound? Maybe I could post a sample here and let you guys be the judge... It looks like the Attachments function doesn't accept audio file extensions, but perhaps I could ZIP it up and attach it?

Give me 'til tonight and I'll have something posted for you to listen to, since I'm too close to all this to have any kind of objective opinion. I also don't have any monitor speakers, and am listening to the playback exclusively through my headphones.

- Ian

 

[iboersma]

Damn, -72 is really good! I have a Soundelux U97 going into a Great River MP2 into my Delta 44 (set at +4), all balanced connections. With the GR's gain set at 50%, I get levels at around -40!!!
I would recommend not sending the output of your BlueTube into the Mic pre of the Firebox. Go mic->pre->line input of PC interface.

The important question, is how does it sound?

Also - the only thing with not plugging my pre-amp output to the MIC 1 input on the Firebox interface is that I then can't take advantage of the on-board pre-amps on the Firebox. With the Shure SM7B dynamic mic being a pretty low-output mic, I need all the boost I can get, though MSHilarious thinks I may be OK with just the +54 DB of gain I get out of the BlueTube pre-amp (foregoing the +45 DB that the Firebox pre-amps give me)...

 

[mshilarious]

Also - the only thing with not plugging my pre-amp output to the MIC 1 input on the Firebox interface is that I then can't take advantage of the on-board pre-amps on the Firebox. With the Shure SM7B dynamic mic being a pretty low-output mic, I need all the boost I can get, though MSHilarious thinks I may be OK with just the +54 DB of gain I get out of the BlueTube pre-amp (foregoing the +45 DB that the Firebox pre-amps give me)...

Yes I think 72dB is enough dynamic range for VO. I'm no radio engineer, but isn't radio dynamic range 40dB or so? Your effective dynamic range is probably 72dB no matter which pre you use--it's just with the Firebox you have to increase gain digitally. Either way you will have low-level noise.

Now, what to do about the noise? Usually you kill it during silent parts, either by editing or with a gate. Editing is cleaner, gates are lazier. But if it's a single VO track, it might not matter at all. If you had to mix together 16 tracks of -72dBFS, you'd want to clean them up first.

Consider the effect of playback of -72dBFS noise: Given an average level of -12dBFS, and average playback level is 85dBSPL, then the level of the noise will be 25dBSPL. That isn't much above the threshold of hearing for an average adult, and is much quieter than the average listening environment.

 

[iboersma]

Yes I think 72dB is enough dynamic range for VO. I'm no radio engineer, but isn't radio dynamic range 40dB or so? Your effective dynamic range is probably 72dB no matter which pre you use--it's just with the Firebox you have to increase gain digitally. Either way you will have low-level noise.

Now, what to do about the noise? Usually you kill it during silent parts, either by editing or with a gate. Editing is cleaner, gates are lazier. But if it's a single VO track, it might not matter at all. If you had to mix together 16 tracks of -72dBFS, you'd want to clean them up first.

Consider the effect of playback of -72dBFS noise: Given an average level of -12dBFS, and average playback level is 85dBSPL, then the level of the noise will be 25dBSPL. That isn't much above the threshold of hearing for an average adult, and is much quieter than the average listening environment.

Damn, I'm glad to have help from guys like you and the rest on this forum. I went from thinking I was S-O-L this morning to thinking I'm pretty well off...

Audition has a built-in noise reduction effect that allows you to profile the noise and then remove it from the whole track. I may experiment with that to see what results I get. Regardless, I'll most likely post a sample file here later today to get everyone's objective opinion on.

Thanks!

Ian

 

[MadAudio]

Just wondering - what will the final format for the VO be?

 

[iboersma]

Just wondering - what will the final format for the VO be?

Good question. My agent didn't have the information, but based on the fact that the script 'reads' like TV and supposedly will comprise 13 episodes, I'm assuming it will be for TV or video... Course, it could be radio...

I've been setting my Firebox at 32 bits rather than 16 as I planned on downsampling after recording.

Just to get the audition out, I'm sending MP3 to my agent...

- Ian

 

[iboersma]

Noise Floor Sample File

Hey all,

Here's a quick sample MP3 file I made tonight on my recording setup. Please let me know what you think of the background noise. Is this acceptable for voiceover recordings for radio and TV?

My resting noise floor is around -67dbfs (I had to add some gain to get closer to 0dbfs, so that's why it went up from the original -72dbfs).

Any and all input welcome. Damn, this Shure SM7 mic picks up EVERYTHING...

- Ian