Conquer clipping, once and for all
Clipping is an eternal problem in audio. It causes terrible distortion and cannot be corrected. Here is the VERY BEST tool to prevent you getting a clip ever again...
All audio systems have an upper limit. The signal cannot go higher in level than this. If you try to make the signal go beyond the upper limit it will be clipped. This means that the peaks will be 'chopped off' at the maximum level.
Clipping causes extreme distortion and is very unpleasant. There are some softwares that can tackle clipped audio to an extent, but they will never preserve the accuracy of the original signal. Once it's clipped, you've had it.
So where does clipping occur?
Firstly in the microphone. Any microphone has a maximum sound input level beyond which the capsule will produce a distorted signal.
Secondly, a capacitor microphone has an internal fixed-gain amplifier. If the sound level is too loud, the capsule will send a signal to the amplifier that the amplifier can't cope with. Peaks in the signal will be clipped.
Next, in the microphone preamplifier. Set the gain too high and the electrical signal in the preamplifier will try to exceed the maximum volume of which the preamplifier is capable. The output signal will be clipped.
Next, the analog-to-digital converter in your audio interface. Send too high a signal level to this and it will attempt to encode a digital signal higher in level than it has digits to describe accurately. Clipping!
Next, next, next...
It is difficult to create clipping in your DAW. Modern DAWs have a huge amount of headroom. Even when you see red lights flashing brightly, you are nowhere near the maximum signal your DAW can handle. However, when you start to see red lights, perhaps in your EQ plug-in, don't make things worse - back off the input level to the plug-in a bit.
The master channel of your DAW. Due to the massive headroom of your DAW, even if you see a red light in the meter of the master channel, you haven't clipped your signal. However, if you try and output this to a file, the digital signal in the audio file will be clipped.
So here are seven places where clipping can occur in a DAW-based studio...
- Microphone capsule (usually distortion rather than outright clipping)
- A capacitor microphone's internal amplifier
- Microphone preamplifier
- Analog-to-digital converter
- Digital audio workstation (unlikely)
- DAW master channel (unlikely)
- Audio file
So what is the best tool to conquer clipping once and for all?
Well it would have been nice if there were a piece of equipment or software to cure all clipping woes, but at least knowledge costs nothing.
And the knowledge is this...
To prevent clipping at any stage of the recording process, firstly watch out for red lights. Secondly, listen for distortion (microphones don't have red lights).
When you detect clipping, back off the input level to the part of the signal chain where clipping is occurring. Reducing the level after clipping has occurred is of no use.
For instance, if the microphone is distorting, perhaps it can't handle the sound level. For preference, change to a microphone that is better in this respect. (Or you could ask the operatic soprano you are recording to tone it down a little!)
If it is the internal amplifier of a capacitor microphone that is distorting, often the mic will have a pad switch that will lower the signal level before it reaches the amplifier.
In any other case, turn down the control that is sending too much level to the part of the signal chain where clipping is taking place.
Since you are already reading Audio Masterclass you either know this already or will adapt to it quickly. The next challenge is to convince the people you work with that avoiding clipping is important. That will be a little more difficult...