pro tools 9 noise floor

[DJ FADE]

pro tools 9
mac osx 10.6.6
lynx aurora 16 converter

i've never run into this before, but since upgrading to pt9 i'm seeing a ton of white noise showing up in pro tools, even when there's no playback and it's just sitting idle. it's usually showing up towards the end of a mix, so it may be plugin oriented or something. right now i have a session open and i'm showing about -32db of JUST NOISE! what's up with that? anyone else running into this?

[slater05]

Some plugins have "analog" buttons on them, which if throughout the signal chain they are being compressed to [bleep][bleep][bleep][bleep] and maximized at the end could end up with quite a bit of noise

[Siddhant Bhatia]

Looks like Plug-in Noise ... also try re-starting pro tools ... Might also be Bus-Based ...

[DJ FADE]

sounds like this must be whats happening. i've just never run into it before! i do have lots of plugs running, and most of them with analog switch on, and am hitting the master with compression, so that must be whats happening. any tips on how to avoid this? or is this fairly common?

[lancemcv]

Turn off the analog modeling on your plugins. Waves CL2A for instance has analog modeling and adds his to the mix especially if you are using a bunch of them, the hiss gets really loud. Didn't they put noise gates on every channel of SSL's to get rid of his.... ..... .... .... ....

[astareawaystudios]

It is very common, when you are loading a lot of hard compressed plugins on individual tracks, and then even more on your mix bus, to get fuzz/hiss/noise.
The waves restoration bundle makes it really easy to cut all of that noise out. In the end, you end up with a clear mix! :)

[lancemcv]

I also had some nasty noise and distortion happen with the new mboxpro but it has not happened lately. THe tracks were actually distorting and after a restart it was gone.
How is PT 9 working for you and what are you using with it. I have had a lot of issues so far with my upgraded setup, Avid Mbox pro, PT 9.0.1 on macpro 8 core OS 10.6.6
My sessions are usually 24 bit 88.2

[spiritsaudio]

lancemcv

My sessions are usually 24 bit 88.2

What is the reason for 24bit 88.2kHz?

[lancemcv]

I would look at the Mbox pros system pref which has its own mixer and it's running in the background whenever you use the mboxpro. There are things like a stereo enhancer and it adds noise, it should be preset to off position.
As far as I can tell it is only a monitoring thing and does not effect what is going to disk but may add noise to the stereo buss.
But you are most likely just getting hiss from the plugins your using, you can hold down the option and command keys and click on a pluggin and all the plugins inserted in the same insert should all be deactivated and you should hear a drop in the hiss, if you do then you know it is the plugins that is causing the hiss. Using noise reduction on your mix is not the right way to fix the problem. Maximizing the mix will bring the plugin hiss out even more as it limits the peaks and brings up the lower levels and floor noise.

in response to '"why 88.2 24bit"
As apposed to 44.1 or 48??

88.2 is twice the sample rate of 44.1 so you are capturing twice as much samples per second. Then when you make a 44.1 16 bit master you add dither to remove the hiss caused by truncating the samples. In the end it makes for a better sounding recording. Tracks some drums at 44.1 16 bit then do the same with a new session at 88.2 24bit. You should be able to hear the difference. Live drums tend to sound more life like and less like samples. Theory has it that 88.2 is better than 96k if you are making a final 44.1 master because it is even math to just cut the sample rate exactly in half.

[Park Seward]

Originally Posted by lancemcv

in response to '"why 88.2 24bit"
As apposed to 44.1 or 48??

88.2 is twice the sample rate of 44.1 so you are capturing twice as much samples per second. Then when you make a 44.1 16 bit master you add dither to remove the hiss caused by truncating the samples. In the end it makes for a better sounding recording. Tracks some drums at 44.1 16 bit then do the same with a new session at 88.2 24bit. You should be able to hear the difference. Live drums tend to sound more life like and less like samples. Theory has it that 88.2 is better than 96k if you are making a final 44.1 master because it is even math to just cut the sample rate exactly in half.

The age-old misunderstanding. Yes, you have twice as many samples but the audio is not reconstructed with less error. That means that a sound at 10k will be exactly the same at 44.1, 88.2 and 96. The sound will be perfectly reconstructed without error as long as the sample rate is more than 2X the frequency. A higher sampling rate lets you record higher frequencies. It does not record lower frequencies any better or with more detail.

A 88.2 sample downconverted to 44.1 will sound the same as a sample recorded at 44.1.

Dither (noise) is added to reduce quantization error. It does not reduce noise.

"Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as "banding" in images. The premise is that quantization and re-quantization of digital data yields error. If that error is repeating and correlated to the signal, the error that results is repeating, cyclical, and mathematically determinable. In some fields, especially where the receptor is sensitive to such artifacts, cyclical errors yield undesirable artifacts. In these fields dither results in less determinable artifacts. The field of audio is a primary example of this — the human ear functions much like a Fourier transform, wherein it hears individual frequencies. The ear is therefore very sensitive to distortion, or additional frequency content that "colors" the sound differently, but far less sensitive to random noise at all frequencies."