Let’s dig a bit deeper and discuss one of the most important concepts you will learn for any technical focus, "Signal Flow".
Audio Signal Flow — The path an audio signal travels from input source to output. So, in simplest terms: "The path an audio (or any signal) takes from its source to its output (destination)."
Simple or complex?
In a home audio system, signal flow can be short and pretty simple.
However, in a recording studio or live venue signal flow can be much more complex.
This complexity can make following the flow difficult and make the troubleshooting process quite involved.
Signal Chain — A series of electronic components.
How do we make all of these different links play well together? In the above illustration the signal chain consists of physical connections. However, a signal chain can be “virtual” within a console or DAW system.
Gain Stage — any point within a signal chain where level adjustments can be made (fixed or variable, increasing or decreasing).
In an audio system the total amount of gain in the system can exceed 100dB. This is usually broken up into smaller steps called Gain Stages where the signal is amplified or attenuated as needed before reaching the output loudspeaker.
Ideal gain staging occurs when each component in the an audio signal chain is receiving and transmitting signal within the optimum parameters of its dynamic range.
Typically the first electronically adjustable gain stage will bring a desired input to Line Level
Following the microphone preamplifier, the audio signal has been amplified to Line Level and then can be processed by devices capable of accepting a line level signal.
Line Level — specified strength of an audio signal used to transmit analog sound between audio components (usually +4dB).
This signal can then be passed from one component to another throughout the signal chain. Special care must be taken at each stage to assure proper gain staging. Improper gain staging will likely result in less than optimal results in the form or excessive noise or signal distortion.
The first rule of troubleshooting: go to the source!
Start at the beginning and investigate the first available connection then move forward, connection-by-connection through the signal chain by process of elimination. This process should reveal the problem allowing it to be resolved. If not, start again; you probably missed something.
As a rule, try to avoid overthinking an issue. More times than not, the problem is simple. That is why a simple systematic step-by-step process will likely reveal the problem. After checking all of the physical connections without resolution, you might then begin walking through the electronic connections (routing and patches) within each piece of gear. One of the best processes to try sooner rather than later is simply plug a known working device (microphone or instrument) into the head-in of your chain. Using a “working” piece of gear will many times fast-track your process. Recently, I have a vocalist bring their w’less mic to me. It would not power on. The first thing I did was replace the batteries (even though the person said they had already done so). This did not remedy the issue. So, I removed the sleeve once again. This time something fell into my hand. It was the contact point for one of the terminal connections. I then noticed that the two batteries were NOT aligned. Upon removing the battery, I could see where the broken piece came from. Mystery solved!
Knowing your signal chain will allow you to understand your signal flow and better troubleshoot problems:
If you do not know what makes up your signal chain it is difficult-to-impossible to troubleshoot a problem.
Stick it in your pocket – Every time you successfully troubleshoot an issue file it away – you will likely need to recall it in the future.
As you develop your troubleshooting skills from experience, you will begin to identify certain reoccurring problems and know where to start your search. This bank of knowledge can be worth more than you know. Over time, you will discover that your process becomes shorter and more efficient. It can also make you look smarter!
Knowledge of signal flow is important - and not just with audio. Knowledge of signal flow can assist us in many areas of life. From audio, to plumbing to our automobile; a basic understanding of signal flow and troubleshooting can serve you well. Good signal flow knowledge does 3 things:
If you know where you want to go and what you want your signal to do, you can make the right gain adjustments to assure proper gain staging.
Understanding the flow of your equipment will allow you to “patch” or format your device not only the proper way, but in some cases in a manner that allows for more creativity (i.e. In which order you insert a compressor or equalizer on your channel strip). Again, if you know how things are flowing, you should be able to track a problem more quickly.
Many reasons!
Most every electronic component has a certain amount of inherent “self” noise. The accumulation of the noise from many components within your signal chain can quickly get out of hand. Improper gain staging can easily exacerbate the problem. This was/is especially true with analog audio systems.
Distortion happens when: