Many people are only vaguely aware of panning laws, which makes sense—if something ain’t broke, there’s no desire to fix it. But panning laws can, in fact, cause issues, and the whole topic is somewhat shrouded in mystery. So, let’s dispel the confusion, and pay particular attention to how panning laws apply to DAW programs that do recording and mixing.
1. Panning laws govern the perceived sound level when panning a mono signal across the stereo field. When a mono input feeds a stereo bus, the panning law determines how you perceive the sound level as the audio sweeps from one side of the stereo field to the other. Without panning laws, panning the sound to the center would sound louder than having it panned to one side or the other.
2. The panning laws in DAWs have their roots in analog mixing consoles. While it may seem that the perceived level would just stay the same as you pan, that’s not necessarily the case. If a hardware mixer’s pan control had a linear taper potentiometer (in other words, a constant rate of resistance change as you turned it), then the sound was louder when panned to center. To compensate, hardware mixers used non-linear resistance tapers to drop the level, typically by -3 dB RMS, at the center. This gave an apparent level that was constant (as in constant power) as you panned across the stereo soundstage.
3. Panning laws aren’t really laws. There’s no panning law specification or standard, so some engineers took subjective liberties with audio’s perceived level when it was panned across the stereo field. Some dropped the center level a little more than usual so that the sides would “pop” more, or to create extra space for vocalists who were panned to center. Then again, some didn’t drop the center level at all, and some did custom tweaks.
4. Panning laws matter with DAWs, even though they don’t have hardware mixers. Different DAWs default to different panning laws (Fig. 1). This is why duplicating a mix on different DAWs can yield different results, and lead to foolish online discussions about how one DAW sounds “punchier” or “wimpier” than another if someone brings in audio files, and then sets the panning and faders to what they think are identical settings.
In Fig. 1, a mono signal of the same level feeds each pair of meters, and each pair is subject to different panning laws. The left meter of the pair shows the level when panned fully (L)eft, and the right meter of the pair shows the level when panned to (C)enter. Note the difference in levels with the panpot panned to one side or centered.
(1) shows an equal power law with a 0 dB center. This boosts signals panned hard left or right by 3 dB, but when panned to center, causes no output level reduction in either channel. (2) is similar, but has a -3 dB center. This means there’s no boost when panned hard left or right, but either channel is down by -3 dB when panned to center. (3) shows a linear panning curve, where hard panning left or right causes no boost—but this particular curve adds a -6 dB drop for each channel when panned to the center, so that the sides are more prominent. This is more about having constant gain than constant power as you pan. (4) is the panning law for a stereo balance control, where the measured signal level is constant at all times, regardless of the panning position.
Note that equal power options often have two possible tapers, sine/cosine and square root. You don’t need to dig too much deeper into this, because the levels with hard panned and centered signals are the same; there’s only a subtle variation to the curve between the hard panned and center positions. Compared to the sine/cosine option, the square root option results in slightly less level difference as you move toward the extreme left or right, and slightly more level difference as you move toward the center.
5. How to make sure you’re using the right law. You’ll typically set a global pan law as a preference, as with Steinberg Cubase or Pro Tools, for individual tracks by using a menu for a panning module, as with PreSonus Studio One (Fig. 2), or on a per track/bus basis, which is what Magix Samplitude does.
The pan law you choose can affect a mix’s overall sound if you have a lot of mono sound sources (with stereo channels, panpots are balance controls, which is a whole other topic). So try mixes with different laws, choose a law you like, and stick with it. I prefer -3 dB center, sin/cos taper, and constant power; the signal level stays at 0dB when panned right or left, but drops by -3 dB in each channel when centered. This is also how I built hardware mixers back in the day, so it’s familiar territory. Furthermore, most DAWs include this option, so when collaborating, it’s easy to match pan law curves.
Do note that if the end file is going to be collapsed to mono, you’re best off using a -6 dB pan law so that there isn’t a big perceived level change when you listen to the final mono track compared to your original stereo mix. Also, if you’re a fan of putting dynamics processing in the master bus, any processing will react differently depending on which pan law you used. Even acoustics come into play here, because the center-channel summing in an acoustic space will vary, depending on the space itself.
Ultimately, with few exceptions, it doesn’t matter which one you use as long as you’re doing projects in the same DAW. You might like having audio panned hard to the left or right to be a little louder…or not. However, if you import an OMF file from another DAW or need to duplicate a mix from another DAW, ask what panning law was used in creating the file. Hopefully, you’ll be able to match it.