Tech Notes

How to eliminate low frequency bass cancellation with proper woofer placement Many local bands and sound companies are unknowingly victims of a type of low frequency cancellation known as boundary cancellation. This phenomenon occurs when a loudspeaker is 1/4 of a wavelength away from a boundary. Assuming that the boundary (like most walls or floors) absorbs little or no energy, the reflection off of the boundary plays against the energy still coming from the speaker source.

In this article I will address the issue of vertically arrayed sound systems, explaining why arraying the larger sound system vertically can immensely improve upon the performance of the same number of components spread out in the horizontal plane. I have been both a student and practitioner of concert-level sound-reinforcement applications for more than twenty years now. I have closely observed major-sound company systems and conducted numerous experiments of my own. One problem, as I see it, is that many smaller sound companies don't array their loudspeakers in a tall-enough vertical array. They tend to spread the system out in the horizontal plane, which increases the overlap of the constant-directivity horns and results in less-than-ideal polar patterns.

1. Frequent Occurrences Of Hard Feedback If you go "ouch" after that last squeal, chances are so did your speakers! This one is compounded by proceeding to use the speakers after they have probably been damaged. 2. Improper Biamplification: Crossover Too Low Or Tweeter Amp Too High Always check your speaker specs for the best crossover points. 3. Not Enough Speaker Systems For SPL Requirements Or Proper Coverage Most folks throw "extra watts" at the same speaker complement: add extra channels of amplification in concert with additional speakers.

This paper is going to address the issue of combining loudspeakers to increase the area of coverage from that of an individual loudspeaker. The concept is generally referred to as arraying the enclosures. Proper arraying insures even coverage with a minimum of mutual interference, and thus allows the sound system to perform as near to a single source as possible. When dealing with multiples of loudspeaker enclosures, the main concern is to maintain the integrity of the high frequency devices. 

If you have read my previous article on the operation of power amplifiers in bridge mode, or if you already understand how bridge mode works, I will present an application to you that employs a CS-X amplifier in bridge mode to drive three loudspeakers in a single cluster or array. In many rooms such as churches and auditoriums where a single source of sound is desired.

You must understand Signal Flow in order to fully comprehend how a sound reinforcement system functions. Understanding Signal Flow lets you know which components connect to each other and in what order, so that you can hook up the sound system correctly each time. I am going to teach you about signal flow by introducing you to the Audio Chain, or the sequence in which your sound reinforcement system's individual components connect together.