The Pan Law
What is the Pan Law and how it affects your mixes.
The problem facing most newcomers to this industry is that once a project is mixed in certain software and the project is then imported in separate mix software, the panned levels go for walkies. This is down to how the software behaves and processes the panning law, compensating for the characteristics of the process.
Panning is the process by which monoaural and stereo sounds are positioned within a stereo sounstage. Think of two speakers and how sound is played through them. Sounds that you hear coming out of the left speaker are said to be panned left, sounds that you hear coming out of the right speaker are said to be panned right and sounds that you hear in the center are said to be panned center.
So, how does this help us with regards to masking and summing?
The first port of call for a producer faced with these problems is to turn to the pan-pot in the DAW or mixer. My moving one sound away from another within the stereo soundstage we eliminate masking and summing in one hit.
The Pan Law
When a signal is panned centrally, the same signal will be output (identically) on both the left and right channels. If you were to pan this signal from the extreme left channel through the centre and then onto the extreme right channel, it will sound as if the level rises as it passes through the centre. The panning law was integrated to introduce a 3dB level drop at the centre. If you were to sum the left and right channels in a mono situation, the centre gain would result in a 6dB rise, so attenuating by that amount became a must in the broadcast industry as mono compatibility is always a prime issue.
So, what the hell is the panning law?
The panning law determines the relationship between the sound’s apparent image position and the pan knob control. This refers to the way the sound behaves when it is moved across the stereo field. The usual requirement is that it moves smoothly and linearly across the field. This is, of course, pertinent to log/anti-log laws. If there was a linear gain increase in one channel and a linear gain decrease in the other channel to change the stereo position, at the centre position the sum of the two channels sounded louder than if the signal was panned full left or full right.
Why do you think we had to attenuate the gain whenever we panned a sound central?
Digital consoles and the digital domain started to change this thinking and accommodate and compensate for this behaviour.
It became necessary to attenuate the centre level by four common centre attenuation figures: 0, -3. -4.5 and -6dB.
The -3dB figure is the most natural because it ensures that the total acoustic power output the studio monitors remains subjectively constant as the source is panned from one extreme of the stereo field to the other. However, it also produces a 3dB bulge in level for central sources if the stereo output is summed to mono, and that can cause a problem for peak level metering for mono signals. However, if you want the panned sound to be perceived as having a constant level when summed to mono, the centre attenuation needs to be 6dB.
Well, the answer is to simply compromise and split the difference and this is what led to most modern analogue consoles working off a -4.5dB centre attenuation.
So, what does this mean to you and how does it help you, particularly if you are working ITB (in the box) and with different software? The answer is quite simple: find out what the software panning preferences are and adjust to taste. Most of today’s software will allow for fine tuning the panning law preferences. Cubase, along with most of the big players, has a preference dialogue box for exactly this. Cubase defaults to -3dB (classic equal power), but has settings for all the standards and I tend to work off -3dB or -4.5dB.
If you stay with the old school days of 0dB, then you are in ‘loud centre channel land’, and a little bit of gain riding will have to come into play.
Check your software project and make sure you set the right preference, depending on what the project entails in terms of the mix criteria.
Topics covered in this video are:
- Explanation of the Pan Law and how it relates to your Mix
- Pan Law Settings
- Mono versus Stereo
- Compensation Values
- Left to Right
- Which Pan Law Settings to use and when