Now that we’re getting ready to get deeper into recording, let’s review the signal flow that happens from the making of a sound to the reproduction of that sound.
First, the acoustic sound source is transduced from sound waves to electrical signals in a microphone. The very low level mic signal is then amplified to a line level signal in a mic preamp. The line level signal is then converted from analog to a digital form in the D/A converter.
After processing in the computer, the digital signal is converted back from digital form to an analog wave form in the D/A converter. The analog electric waveform is finally amplified up to speaker level and transduced from electrical energy to acoustic energy via a speaker.
After processing in the computer, the digital signal is converted back from digital form to an analog wave form in the D/A converter. The analog electric waveform is finally amplified up to speaker level and transduced from electrical energy to acoustic energy via a speaker.
When you examine the entire flow chart you can see that there are 6 major components that are responsible for capturing and reproducing an acoustic sound.
1. Microphone
2. Mic preamp
3. A/D converter
4. D/A converter
5. Amplifier
6. Speaker
All 6 of these components play a significant role in the quality of the recording process. The first 3 determine the quality of the sound that will be recorded. The last 3 affect the quality of what we hear as being recorded.
In most cases, the emphasis in recording is on the first 3 of these components. The logic in this is that even if the reproduction side of the flow chart is less than ideal, as long as the original sound is captured to the best of our ability we can eventually produce a good quality product for others to listen to. On the other hand, even if we have the best reproduction equipment that money can buy, we can’t save a bad recording.
Let’s take a closer look at what happens to audio signals once they’re in a digital format in the DAW.
There are 2 separate cases to consider here:
1. Audio Track
2. Auxiliary Track
When recording audio in the DAW the first thing to do is to create a new “Audio” track. Once created, the I/O selection must be made. The choices for this are either an input from the A/D convertor or a bus that’s being routed from another track in ProTools.
Because this is an audio track, the rest of the signal flow gets it’s input from the return of audio that’s been recorded to this track. If there is no audio recorded, nothing happens because there is nothing to process.
If audio is in the process of being recorded, the processing will be applied to the output from the recorded track. In other words, the audio will be recorded without any processing and then played back through the remainder of the track for processing.
You can think of an audio track in ProTools as having 2 separate signal paths:
1. The path to storage
2. The return from storage
If we compare the Audio Track signal path to the Auxiliary path, the only difference is that the Aux Track processes the signal that comes in from the Input Select directly, without going through the recording process.
Once again, the input selection on the track can switch between either a signal from the A/D converter or a bus routed from another ProTools fader. In this case however, once selected any processing that may have been implemented with either inserts or sends will take place immediately and will not be recorded on this track.
When we add the detail of how signals are routed in a DAW to the overall system flow chart, we have a clear picture of how sound is processed in recording with a DAW.
Keeping this picture in mind will help when it comes to using DAWs to record and mix audio.