I mentioned in my previous article (What, Me Worry?) that I’ve been troubled by the lack of fundamental audio and acoustics knowledge often displayed in our industry.
And because of this, there are misconceptions that are difficult to stamp out.
So in an effort to help, I’ve whittled down a concentrated list of the top technical concepts I think everyone in our business should have under their collective thumbs.
Of course there are many more important ideas and concepts that we all need to know, but to me, these are the ones that translate very directly into a better product.
10. The Speed of Sound and Delay
First, we all benefit from understanding that sound waves move through a fluid medium - i.e., air - and thus the speed of sound is related to temperature and the density of the air, depending on altitude.
At sea level and “room temperature” (generally speaking 68 degrees Fahrenheit or 20 degrees Celsius), sound travels at about 1,130 feet or 343 meters per second.
That’s actually pretty slow when you think about it. In fact, it’s fairly easy to observe a lag between what you see and what you hear when located more than 40 or 50 feet from a sound source.
This is the reason why we need “delay towers” and not just “loudspeakers” when covering a very large area. Don’t forget that at higher altitudes, sound travels slower, and at higher temperatures, it travels faster.
As a result, it’s wise to carefully measure delay times for towers before setting them - the standard formula may not work for your particular setting, and also keep in mind that settings might need to change as the day wears on.
9. Loudspeaker Crossover Frequencies
Different loudspeaker drivers have different frequency ranges and need to be “crossed over” or properly filtered for the cabinets to work well.
But we should also be aware that different engineers have different approaches, and that different crossover schemes can have a radical effect on the ultimate sound of the system.
The exact corner frequencies chosen, the slope/s of the filters, and whether the crossovers are active or passive all make a difference.
For instance, a 2-way box that has an internal, passive crossover will sound different if bi-amplified with an external active crossover.
Some of this has to do with phase, and some of this has to do with filter slopes. I suggest reading up on the subject, starting with loudspeaker design guides. There’s a whole world of information available on this subject.