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Pan Control: The Most Misunderstood Knob in Logic

Saturday, June 6, 2015 17:03

The Pan Knob. Virtually every Channel Strip on a Mixer has one. It is an essential element of every mix, and pretty much everybody uses that control in every Project. But does everybody also understand what the Pan Knob really does? If you can''t answer that question, or want to check if your answer is right, then read on. All your future Logic mixes might depend on it!


The Danger

Look at these two Channel Strips. Both have the typical Pan Knob that you use to position the audio signal in the stereo field anywhere between the left and the right speaker. But, and here lies the danger, these are two different Pan Knobs despite their identical appearance!

Introduction

The problem with the Pan Knob is that it seems to be so simple that users often don''t think much about it. It comes down to: "I turn the knob to the left and the sound is coming from the left speaker, I turn it to the right, and the sound is coming from the right speaker." Although this describes the basic concept, there is a little bit more to it. The good news is that the little bit of extra information is not that complicated to understand. It is more like an awareness, and every Logic user should be aware of that Pan Knob functionality, because it determines how you "mix" you music.


Level & Process

There are two types of procedures when you think about what you are doing when you "mix" a project,: Leveling the signals and processing the signals:

  • Leveling: With this procedure, you set the signal level on each Channel Strip to determine how much of that signal will be sent to the output bus. The main component for doing that is the Volume Fader, but also the Mute Button, which sets the volume to -∞dB ("negative infinity", which means, Fader all the way down), and therefore, eliminating it from the mix. And here is the important part: The Pan Knob is also a component that determines the signal level, as we will see in a moment.
  • Processing: This is the category that usually involves any kind of audio effects that lets you alter the sound of the signal and not just its level. For example EQs, reverbs, delays, etc. You could argue that dynamic effects (i.e. compressors, limiters) are effect processors or level controls, but that is a different discussion.


Pan Knob - What for?

The first question for any control is: "Why do I need it, and what is it for?"

To find out the reason for its existence, let''s look at the Pan Knob in following example: You have recorded a Jazz ensemble using five microphones ➊, recorded on five Tracks in Logic. Five Channel Strips represent those five Tracks, each carrying a single-channel audio signal from each microphone. A "single-channel audio signal" also refers to as a "mono signal". However, you are mixing in stereo. That means, your five Channel Strips are routed to a stereo output bus ➋, representing a two-channel audio signal, hooked up to your left and right speaker ➌. So how is the mono signal "converted" ➍ into a stereo signal? That''s what the Pan Knob ➎ is for.


This is a very simplified routing configuration to demonstrate the purpose of the Pan Knob: "Route a mono signal to a stereo signal". However, this is only one possible configuration of a Channel Strip. We have to make a detour first for a closer look at the Channel Strip to be prepared for any "surprises" regarding the Pan Knob.


Channel Strips

A Channel Strip in Logic is the component where the audio signal "runs through" and where you apply the various audio processing and level treatments to that specific audio signal, for example, a vocal track. One important aspect that is often overlooked is, how many audio channels does that audio signal have that runs through that Channel Strip?
  • Traditional Mixing Console: The Channel Strips on most hardware mixing consoles can carry only a mono signal that ends up at the Pan Knob where you route it to the stereo output bus. This is similar to the example in the previous diagram. Some consoles might have one or a few stereo Channel Strips, mostly for hooking up a stereo source (i.e. CD Player or a stereo output of an instrument).
  • Logic''s Mixer: A Channel Strip in Logic is way more flexible. It can carry a mono signal, a stereo signal, and even a multi-channel surround signal. In addition, the channel configuration can change in the Channel Strip. For example, you can feed a mono signal (1 channel) to its input, but use a 5.1 surround Reverb effect (6 audio channels). Now the signal that feeds into the Pan Knob doesn''t have one channel, it can have six channels.


That means that the functionality of the Pan Knob depends on the channel configuration of the Channel Strip,how many channels "arrive" at the Pan Control. Let''s look at five configurations in the next section.


Different Pan Controls

Here is a screenshot that shows the different configurations of five different Channel Strips and how that affects the Pan Control.

  • Mono to Mono ➊ - no Pan Control: If the Input ➏ is set to a mono channel and the the Output ➐ is also set to a single channel, then the Channel Strip will have no Pan Control at all ➑. The signal on the Channel Strip is now routed directly to that one selected output bus.
  • Mono to Stereo ➋ - Pan Pot: This is the standard configuration where you have a mono input ➏ and a stereo output ➐, the classic "Pan Pot" ➑ (Panoramic Potentiometer) situation.
  • Stereo to Stereo ➌ - Stereo Balancer: This configuration has a stereo input and a stereo output. Although the Channel Strip still displays the Pan Pot, it functions as a "Stereo Balancer". This is one the most misunderstood controls on the Channel Strip. Please note that the Meters ➒ on the Channel Strip indicate the number of channels at the input of the Pan Control. We will have a closer look at that important control in a minute.
  • Stereo to Stereo (Binaural)- Binaural Panner: When you select the "Binaural" option from the Output Menu, then the Pan Pot changes to a Binaural Panner.
  • Multi-Channel to Multi-Channel ➎ - Surround Balancer: If you select "Surround" for the Output Bus, then the Pan Knob changes to a Surround Balancer (or Surround Panner).


I will discuss the option ➍ and ➎ in the Surround chapter of my book "Logic Pro X - The Details". For the purpose of this article, I concentrate on option ➋ and ➌.


Mono to Stereo

So what is happening inside the Pan Knob and how does it work? Here is a diagram where I show a model that makes it easier to understand the functionality.

This is what happens when you feed a single channel (mono signal ➊) into the Pan Control.

  • The signal will first be split into two signals ➋.
  • The left signal runs through a volume fader ➌ before it is added to the left bus ➍ of the Stereo Output.
  • The right signal runs through its own volume fader ➎ and is added to the right bus ➏ of the Stereo Output.
  • If the Pan Knob is in the center position, then both fader positions are the same, distributing the incoming mono signal equally to the left and right Stereo Output Bus.
  • Turning the Pan Knob to the left will lower the right volume fader ➎ and the signal appears to be moving in the stereo image to the left. The more you turn to the left, the more the right fader is turned down, all the way to -∞dB (mute). At this moment, you will hear the signal on the Stereo Output only coming out of the left speaker ➍.
  • Turning the Pan Knob to the right will lower the left volume fader ➌ and the signal appears to be moving in the stereo image to the right. The more you turn to the right, the more the left fader is turned down, all the way to -∞dB. At this moment you will hear the signal on the Stereo Output only coming out of the right speaker ➏.



Stereo to Stereo

This is what happens when you feed two channels (stereo signal ➐) into the Pan Control.
  • You still have the two faders inside the Pan Control.
  • The only difference is that the incoming signal doesn''t have to be split up, because you are already feeding the Pan Control two signals.
  • The left channel of the Channel Strip is feeding the left volume fader ➑ inside the Pan Control and the right channel of the Channel Strip is feeding the right volume fader ➒ inside the Pan Control.
  • Turning the Pan Knob to the left will lower the right volume fader ➒. The more you turn to the left, the more the right fader is turned down, all the way to -∞dB. At this moment, you will hear the signal on the Stereo Output only coming out of the left speaker.
  • Turning the Pan Knob to the right will lower the left volume fader ➑. The more you turn to the right, the more the left Fader is turned down, all the way to -∞dB. At this moment, you will hear the signal on the Stereo Output only coming out of the right speaker.



Beware of the Stereo Balancer

Please note that with a Stereo Balancer in Logic, the left channel of the stereo signal will never be distributed to the right output bus (coming out of the right speaker) and the right channel of the stereo signal will never be distributed to the left output bus (coming out of the left speaker). Although it appears that you are panning the stereo signal to the left or right, you are just changing the level of the left or right channel of the stereo signal on that Channel Strip.


How to Spot the Stereo Balancer

The important aspect of this article is to realize that the Pan Knob doesn''t give you any indication if it is functioning as a Pan Pot ➊ or a Stereo Balancer ➋. The visual giveaway is the Volume Meter.

  • If you have a single channel meter, ➌ then the Pan Knob functions as a Pan Pot ➊.
  • If you have a dual channel meter ➍, then the Pan Knob functions as a Stereo Balancer ➋.


Conclusion

After reading, digesting, and trying out the information of this article, you will hopefully be more aware of the Pan Control on the Logic mixer, and whenever you touch it, realize what is actually happening.


Panning a Mono Signal

With a mono signal on a Channel Strip, for example a guitar track, you can use the Pan Pot to easily position the signal in the stereo field by moving the Pan Pot to the left or right (and even automate a pan movement).

Panning a Stereo Signal

However, if you''ve recorded the guitar in stereo or use any stereo synth sounds from an Instrument Plugin, then you have to think twice if you really want to use the Pan Control. Now functioning as a Stereo Balancer, the guitar would appear more to the left or right depending on where you turn the knob, but you are actually "loosing" (lowering the level) the left or right channel of the stereo signal if you are doing so.

  • Direction Mixer

Other DAWs use different methods how to deal with the problem of "Panning Stereo Signals". In Logic, you shouldn''t use the Pan Control on the Channel Strip, instead, you can use an Audio FX Plugin called "Direction Mixer". It is located in in the Plugin Menu inside the "Imagine" subfolder.



More Panning Please

This article covers only the basics of the Pan Knob in Logic. I will discuss all the routing scenarios regarding the pan controls in much more detail in my book "Logic Pro X - The Details". Especially with the different output configurations of the Audio FX Plugins and the various surround sound format, routing can get a little bit more difficult.


Pan Law

And last but not least, Pan Law. This is an even more mysterious configuration that needs to be understood when using any Pan Control in your mix. I created special diagrams in my book to demystify even this slightly more complex topic so it is very easy to understand - once and for all.




Graphically Enhanced Manuals (GEM)

Please check the other books in my best-selling “Graphically Enhanced Manuals” (GEM) series, available as PDF files, interactive multi-touch iBooks on Apple’s iBooks Store, or as printed books on Amazon.

http://DingDingMusic.com/Manuals/ 

Thanks for your time and interest,

Edgar Rothermich