The Art & Science of Audio & Video

The Five Faces of Distortion

As a waveform passes through an audio or video system any deviation from the original signal is considered to be distortion. Therefore the output signal is no longer the same as the input signal only greater in amplitude, it has been changed and is now “distorted”. Continue reading

July 14, 2008 Posted by | Class: E=MC2(+/-3db) | , , , , , , , , , | Leave a comment

Haas Effect; (Precedence Effect)

The Haas effect, first discovered in 1946 and named after Helmut Haas, also commonly referred to as the Precedence Effect and/or law of the first wave front. The Haas effect is a psychoacoustic effect having to do with the auditory phenomena that allows us to localize sounds emanating from anywhere around us. This is achieved by using a combination of sensory responses to the varying physical differences between the sounds we hear such as arrival times, level of intensity and phase interactions. Our use of varying arrival times to determine location is a result of simple anatomy. The geometry of the human head with our ears spaced apart and a barrier in between means that direct sound will arrive at the ear closest to the source first and then arrive at the ear furthest away allowing us to locate the source of the sound. Continue reading

July 6, 2008 Posted by | Class: E=MC2(+/-3db) | , , , , , , , , , | Leave a comment

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

Balanced Input or Stereo Input? Mic Input or Line Input?

I want to discuss a topic that I get asked about constantly. It’s the confusion surrounding balanced inputs verses stereo inputs and the true differences between mic and line inputs. First and most obvious are the balanced and stereo. This is something that has become a more prevalent problem in recent years because of the popularity of portable MP3 players and the use of laptops running special software for athletic programs and multimedia presentations. So here’s where the problem usually starts, someone takes the convenient 1/8″ stereo mini and assumes that the fact that it has a Tip, Ring and Sleeve translates into a balanced input of pin 1(G), 2(+) and 3(-). Well as you’ve probably figured by now this is not the case. Continue reading

June 22, 2008 Posted by | Class: E=MC2(+/-3db), FAQ's | , , , , , , , , , , | Leave a comment

What is Sound?

Physiologically, sound is a vibration in a medium once received by the ear. To achieve this you need three key elements.
1. a sound source
2. a medium for the sound to travel through
3. an ear to detect the sound

In the physical realm sound is a disturbance that creates the sensation of sound. By definition sound is a simple form of energy. When there is a series of disturbances in a medium, such as variations in pressure and alternations in direction of molecular movement the ear interprets that as sound. Sound is objective and therefore exists by definition regardless if there is any living thing to interpret it or be affected by it. So the answer to the old adage, “If a tree fell in the forest and no one was there to hear it would it make a sound?” is yes it would make a sound. Continue reading

June 10, 2008 Posted by | Class: E=MC2(+/-3db) | , , , , , , , | Leave a comment

Critical Distance & Microphone Placement

A microphone is the first component in any speech recording or transmission system. Its function is to convert acoustic sound waves into an equivalent electrical signal. This signal can then be recorded, transmitted, amplified, or modified. Continue reading

June 6, 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

How to properly set delay speakers

When configuring a sound system how do you properly set the delays?

The ultimate goal when setting up delay speakers is for the listener to not even notice the delay speakers are there. Yes, as silly as it sounds it’s true. A properly configured delay will give the illusion that the sound is still coming from the source and not the delay itself. There are several ways to go about a proper setup for your delays. Believe it or not you can actually configure a delay very precisely with a tape measure and not expensive test equipment. Just remember one very simple rule, sound travels 1130 feet per second (at sea level with 70% relative humidity at 72 degrees). In other words sound will travel 1.13 feet every millisecond. So if your delay speaker is 35 feet away from you primary speakers a delay of 31 milliseconds would be right on the money. Of course there are several sophisticated and expensive electronics to do the same thing. They use a calibrated microphone to compare the arrival times of a reference signal from the main speakers and the delay speakers as it arrives at the microphone. This difference in arrival times is obviously your delay time.

However there is also a phenomenon known as the HAAS effect which is too in depth to discuss in one post but what’s important to know is how it relates to settings delay times. In the study of psychoacoustics it is found that often times delaying the “delays” even further behind the arrival time of the primary speakers actually enforces the perception that the sound is originating solely from the primary speakers. This is because the secondary arrival is suppressed due to “involuntary sensory inhibition” which correlates to the human ear’s ability to localize sounds.

by Jason Levert

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

The Critics Have Spoken but It’s You We’re Listening To.

At Gain11 I do my best to avoid subjective disagreements with any patrons on or offline. However recently I was heavily criticized for not going more in depth into more of my articles and/or answers. I kindly remind those critics that it is not our objective to be a replacement for qualified teachers and the many well-known training facilities spread about the country and of course those across the pond . I my self will spend my time in the shadows of these highly regarded teachers learning for years to come. We aim to be a resource that prepares those who want to take that next level and invest money in these classes and take full advantage of all of the professional and world-renowned facilities available to us all. There are plenty of books available that are too advanced for the beginner and those just interested in learning more about the field. If we can bridge that gap and get those just starting to a point where they can read these books without being overwhelmed in just the first chapter then we have accomplished our mission.

Of course with all this said we always encourage any feedback our readers may have critical or otherwise. If there are specific topics and or areas of study you would like to see us address just drop us a line and we will be sure to meet all of your requests as quickly as possible.

by Jason Levert

March 25, 2008 Posted by | A/V News, Class: E=MC2(+/-3db), FAQ's | Leave a comment

Convenience vs. Quality (finally getting the attention it deserves)

I have long be an advocate that MP3’s and all other heavily compressed audio formats have been the downfall of quality audio. I have been pleasantly surprised to see that some of the mainstream magazines both published and online have joined the crusade and are speaking out on their concerns as well. I recall back when we chose our CD players depending on whether or not it had Burr Brown DAC’s and Continue reading

March 23, 2008 Posted by | A/V News, Class: E=MC2(+/-3db) | , , , , , | Leave a comment