The Art & Science of Audio & Video

Inverse Square Law

The inverse square law is probably one of the most widely used fundamental of physics used in the field of audio. As you advance through your career you will continue to use this particular formulation on an increasingly frequent basis. You will use it at the very beginning of your system designs when trying to determine what speakers to select and what amplifiers will be required to power them. It can also be used to assist in the setting of delays speakers and much more. It will be a very valuable tool to have in your audio knowledge toolbox. Simply stated the definition of the inverse square law is as such. Continue reading


June 28, 2008 Posted by | Class: E=MC2(+/-3db) | , , , , , , | Leave a comment

Power amps with & without controls…..what gives!

How do power amps work that have no volume controls on them?

Actually no amplifiers have “volume” controls. The power amp it self is fixed at a given output, let’s say 100W for example. If the amp does have a “volume knob” it is actually a control associated with the pre-amp stage of the unit. When turning that knob you are actually adjusting the input sensitivity. So in a scenario where you have a separate pre-amp and amplifier the pre-amp will take the signal from the source component and allow you to manipulate the signal with the use of maybe tone controls, attenuation, etc. The signal then is passed along to the amplifier, which is once again fixed at a given output. So controlling the amount of attenuation on the pre-amp will have a direct effect on the amplitude of the signal at the input of the amplifier. So the amp will amplify whatever signal is at it’s input by the same amount regardless of amplitude.

So simply put the amplifier is only capable of 100W of amplification. How “loud” it plays (or the resulting amplitude at the output) depends on the level of the signal you present to it at the input stage. Fort the units that do have attenuation controls you have the luxury of controlling it sensitivity to the input signal.

by Jason Levert

March 29, 2008 Posted by | Class: E=MC2(+/-3db), FAQ's | , , , , , , , | 1 Comment