When I was recently calibrating my monitors, I wondered if I should use the pink noise generator shipped with Pro Tools. I did some comparison testing between Bob Katz’s Stereo file and the Pro Tools’ pink noise generator plugin to find out.
So, is it okay to use the pink noise in Pro Tools? The testing identified a noticeable difference between the Pro Tools pink noise and the one downloaded from didgido.com. The pink noise in Pro Tools is ‘quiet’ and calibrates the monitor levels too high.
The plug-in supplied with Pro Tools is very convenient to pull into a session compared to downloading and importing an audio file. From the testing carried out with my monitors, in my home studio mixing room, use digido download for calibration. For other pink noise uses, however, the Pro Tools version seems to be ok.
The purpose of the comparison was to see if there is any difference between the monitor gain controls (on the back of the monitors) and the console volume setting when calibrating using the two pink noise sources.
The monitor calibration was carried out to a combined stereo SPL of 79.3dB, with individual right and left channels at 76.3db. For mixing at K-20 and mastering at K-12, 79.3dB is the volume I chose for my mix room, based on my experience. Your own home studio level will, in all likelihood, be different – see the explanation further down.
|Pro Tools Signal Generator||Bob Katz's Stereo Wav File|
|Monitor Gain||Focusrite USB Interface||Console Volume||Monitor Gain||Focusrite USB interface||Console Volume|
|Notch 28||Notch 26||12 o'clock||K-12||10 o'clock||Notch 19||Notch 17||12 o'clock||K-12||10 o'clock|
|K-20||12 o'clock||K-20||12 o'clock|
Table 1: Results Comparison Between Pro Tools Signal Generator and Bob Katz's Stereo Wav File
Figure 1: Yamaha MSP7 Studio Monitors Gain Controls
The method follows a standard procedure for monitor calibration. Pink noise is played through each channel separately, and the Yamaha MSP7 Studio Monitors gain controls, on the backs of the units, are adjusted so that the SPL meter reads 76.3dB. The combined channels add an additional 3 decibels so that the SPL meter reads 79.3dB in stereo.
For K-20 monitoring, the Focusrite and Mackie Big Knob monitor controls are both dialed to 12 o’clock. Dial settings at 12 o’clock are useful as they are easy reference points to remember.
After calibrating the monitors with each Pink Noise source, the testing concluded that the Pro Tools Pink Noise is not suitable for setting monitor gain. But, the Pro Tools Pink Noise is ok for other uses of Pink Noise, like establishing your room’s SPL level or mixing using the Pink Noise technique.
Finally, play a few commercial CD tracks at this level and make sure the room is not vibrating and things are not falling off shelves.
Pink noise is an audible signal that is random in nature but has equal energy in each octave band across a frequency spectrum. The SPL of pink noise falls 3dB for each octave band as frequency increases.
We don't need to understand all the ins and outs of pink noise to use it for calibration, so don't worry too much about the technical details. If you are calibrating your home monitoring setup, you simply need to follow the calibration procedure.
Pink noise is used for calibration because:
First of all, there is a lot of chatter on home studio forums that give a range of 85dB to 90dB. If you have a home studio, my advice is to ignore these numbers.
Bob Katz’s own advice is to calibrate your Studio Room to 86 decibels, but if you follow his posts at digido.com, he goes on to say 86dB is a suitable level setting for reasonable size studios with mainstream size monitors. So, if you are mixing in your bedroom or spare room, 86dB is usually way too loud.
We are going to play some commercial music through your home studio and use that to determine realistic listening and mixing volumes.
Import a typical, commercially produced song that you like into your session. I use ‘Four Seasons’ by Sting as this is the type of music mixing that I generally record, mix, and master in my home studio. The Sting song provides a good representation of songs that I work with and has a very well defined low and high end.
Play the song and turn up the volume until it's way too loud and make a note of the dial position. Next, turn it way down until it starts to get challenging to pick out the bass and high frequencies. On the Sting song, I listen out for the bass vocals and hi-hat. Again, note the dial position.
Now set the dial just below halfway between the two noted positions and listen to the whole song from start to finish. Can you hear the bass guitar, kick drum, vocal, individual guitar notes, and the hi-hat well? Can you pick them out easily? Adjust the volume one more time so that it feels comfortable and will not fatigue your ears.
Great! Now increase the pink noise level until you are masking out the music’s vocal (be sure to raise the right and left channels equally). Next, mute the music track and measure the SPL in the listening position. In my room, I measured 79.3dB at this point.
Figure 2: Mackie Big Knob Desktop Studio Monitor Volume Control
The value you are measuring here is a good indication of what your listing volume should be for mixing in your room.
Amazing! You have found the volume level that suits your ears, your workspace, your system, and in the genre you mix most!
Follow these steps and try out this mixing technique:
Finally, adjust the mix bus fader so that the compression is at the desired gain reduction amount - for example, about 3dB. And enjoy a well-balanced mix!
How do I generate pink noise in Pro Tools? To generate pink noise into the left and right monitors, follow these steps:
Figure 3: Generating Pink Noise with the Pro Tools Signal Generator
Finally, make sure that there are no other active plugins is in your chain - for example nothing on the mix bus or on the master fader. The signal generator will produce a continuous stream of pink noise. To mute the pink noise either bypass the plugin or press mute on the track.
Where can I download calibrated pink noise audio files? Head over to Bob Katz’s site digido.com. Under the resources tab, follow the download link to access the download page. You will be asked to create a login with your email (create a username and password). After you have successfully logged in and go to the download page scroll down to the general section and expand the general sub box. In this section, you will find three Pink Noise files.
If you use the stereo file, hardpan right, and left, and set two auxiliary tracks to be able to mute the right and left channels individually. Don’t adjust the pan pots.
What is the difference between RMS and peak level monitoring? RMS is the abbreviation for Root Mean Square , and is a calculated average value of sound pressure levels. Imagine a sound wave as the valleys and mountains in a landscape. The mountains are the loud parts, and the valleys are the quieter parts. In the landscape scene RMS is ground level. Peak levels are the tops of the mountains. Peak levels are excellent for making sure we don't push audio signals too high and clip our audio.
Our ears naturally even out sound as the human ear cannot react quickly enough to minute movements in SPLs and therefore averages out audio. Our ears don't do the same calculation as an RMS meter, but it's the same principle, and that is close enough for mixing.