Signal Flow

The most basic skill any audio engineer must master is an understanding of signal flow. Signal flow is the path audio must follow to reach its intended destination. Basic audio signal flow with regards to recording consoles falls into two basic sections, the channel path and the monitor path. Each of these paths has a different task, though the operation and basic layout is quite similar.

The channel path of a recording console has one specific task; moving audio from the microphone to the multi-track recorder. The signal begins at the microphone transducer and moves into the mic panel. The signal then moves through the pad, phantom power, preamp and mic trim. This collective section is generally referred to as the mic preamp. Next in line is the phase switch, which can flip the polarity of the audio signal. Following the phase switch are the filters, the most commonly used of which is the high-pass filter. The next component is the equalizer, which can be used to boost or attenuate specific frequencies or bands of frequencies within the signal. The insert sends and returns follow the equalizer, and these can be used to patch in pieces of equipment not directly attached to the console. Next is the channel fader, which is essentially a variable amplifier before the multi track. After the fader is the odd/even pan pot, and the routing matrix. The routing matrix is used to assign channels from the console to channels into the multi track recorder.

The Monitor path is used to hear the audio coming out of the multi track recorder. The first item in line coming out of the multi track is the cue sends. These are used to send audio to artists in the live room, where they can hear it. Next in line is the monitor fader, which operates much the same as the channel fader. The monitor fader is much more likely to have adjustments made, as moving the channel fader from unity gain can add distortion and noise to the recorded signal. Following the monitor fader are the aux sends. These are often used to patch in temporal effects such as reverb and delay. The aux sends can be attenuated, unlike the insert sends and returns that they operate similarly to. Next in line is the monitor pan pot. This pan is used to move the signal to the left or right within the stereo field. After the monitor pan is where the signal from the aux sends returns to the console. This is referred to as the aux return. The signal from the monitor pans and the aux returns are then summed into two channels in the stereo bus. The signal from the stereo bus then passes through the master fader, where it is then sent to a control room amplifier, and finally to the left and right monitors.

Each of these stages allows a recording or mixing engineer to control certain aspects of the signal and refine the sonic characteristics of the audio. It should be noted that many consoles allow the audio engineer to change the order of some of the individual components within the signal flow. Therefore, the engineer should understand the particular signal flow of their console and when to make necessary adjustments to that signal flow.

References

http://tweakheadz.com/signal-flow-1/

Business Plan Leaders

Carl Schramm is an economist and professor at Syracuse University, and strangely enough, not a fan of in depth business plans. His background as an entrepreneur has led him the conclusion that business plans should be minimal at best. The realm of business is constantly shifting and ever-changing. Schramm believes that the business plan would be obsolete and out of date the minute it is finished being written. Schramm also believes that the success of a business is more dependent upon the individual entrepreneur, more so than the business plan. Schramm outlines the traits that the ideal entrepreneur should embody, specifically the traits of embracing change and having well rounded experience. These traits are characteristics I find in myself, given my diverse background and numerous skills. My background in the military has afforded me the capability to adapt and embrace change to survive in an entrepreneurial setting. This same background also has forced me to observe static systems that have room for optimization. It is good to know that these observations may serve me well in the development of my own business.

Carlos Slim is one of the richest men in the world, and the chief executive of Telmex, the largest telecommunications and cell phone company in Mexico. As such, Carlos Slim is well versed in creating a successful business. Much like Carl Schramm, Carlos Slim eschews the typical business plan and instead exposits a number of straightforward rules for the entrepreneur to follow. I particularly appreciate his devotion to simplicity and clear goals. Minimizing complicated hierarchy and staying focused on clear goals helps mitigate expenditure on unimportant assets and allows the entrepreneur to work hard on tasks that matter. I also appreciate the focus on positivity, creativity, and not seeking wealth for its own sake. The concept of bettering the world through business is one that many business would do well to take to heart.

Microphone Transducers

In the world of the professional audio engineer, no tool is more ubiquitous than the microphone. Skill with microphone selection and placement separates the inexpert recording engineers from the true professionals. Skill with microphones is based entirely on knowledge of the tool. One of the most basic skills is determining the proper transducer type for the proper application. Microphone transducers fall under three types; dynamic, condenser and ribbon.

Dynamic microphones are some of the most common microphones found in the recording studio, and elsewhere. Dynamic microphones are inexpensive to produce and relatively robust in construction. Dynamic microphones lack the brightness of condenser microphones due to a lack of responsiveness in the diaphragm of the dynamic microphone. The diaphragm is dampened do to being attached to the voice coil. Dynamic microphones typically have a cardioid polar pattern.

Condenser microphones are some of the most intricate and consequently most expensive microphones produced. Condenser microphones have some of the best quality frequency responses of any microphones, with a characteristic brightness in the high frequency range. This brightness is achieved by the thin metallic diaphragm, sometimes only 10 microns thick. Condenser microphones are also distinguished by their need for what is referred to as “phantom power.” Phantom power is 48 volts of electricity used to polarize the transducer or “capsule.” Sound is transduced into electric audio signal by the changes in voltage produced by the diaphragm changing distance in relation to the back-plate. Condenser microphones can have a variety of polar patterns, such as omnidirectional, bidirectional, cardioid, hyper cardioid and some condenser microphones can switch between two or all of these polar patterns.

Ribbon microphones are the oldest transducer design of the three. Ribbon microphones utilize a thin foil ribbon that oscillates between the poles of a large magnet. Ribbon microphones are considered fairly fragile due to the thinness of the ribbon and the necessity to be placed at a neutral point within the magnetic field. The ribbons can be easily deformed by high sound pressure levels. Ribbon microphones, by virtue of their design, have a bidirectional polar pattern.

Knowledge of transducer types eases the selection process when choosing microphones for specific applications. Transducer type is typically the first criteria considered when selecting microphones. Knowledge of transducer types helps in retaining knowledge of other criteria such as frequency response characteristics and polar patterns. It is therefore critical for any aspiring audio engineer to familiarize themselves with microphone transducers.

References

·      http://www.shure.co.uk/support_download/educational_content/microphones-basics/microphone_transducer_types

http://www.dawsons.co.uk/blog/what-is-phantom-power

Polar Patterns

Microphone polarity and polar patterns are vital knowledge to any that seek to enter the field of sound design. Microphones are critical tools of the trade that see use on a near constant basis. The knowledge of polar pattern properties can allow a sound designer to maximize the effectiveness of a smaller number of microphones and increase the quality of recordings. Polar patterns fall into a number of categories; cardioid, hyper-cardioid, bi-directional, and omnidirectional.

Omnidirectional microphones record 360 degrees around the capsule of the microphone with minimal phase cancelation. Many times these microphones are used as room microphones, as they capture much more than single sources. These microphones are also useful for recording orchestras.

Bi-directional microphones or  “figure 8” microphones have a polar pattern that extends to the front and rear of the capsule with maximum phase cancelation at the 90 and 270 degree positions. Bi-directional microphones were once very popular as the standard configuration for ribbon microphones, which continues to this day.

Cardioid polar patterns are the most common polar patterns on the market. Cardioid polar patterns have a maximum sensitivity at 0 degrees to the capsule and maximum rejection at 180 degrees to the capsule. There is typically a gradient of phase cancelation between 0 and 180 degrees. Cardioid polar patterns are most closely associated with dynamic microphones, though are commonly found on condenser microphones as well.

Hyper-cardioid polar patterns are a relatively recent addition to the list of polar patterns. Hyper-cardioid polar patterns are very similar to cardioid polar patterns; however the maximum rejection at 180 degrees to the capsule is replaced with another lobe of sensitivity. This allows the 0 degree sensitivity to be more selective and allow greater rejection off axis.

Knowledge of polar patterns allows recording engineers and sound designers to select the best microphone for the job in much the same way a carpenter selects the most appropriate tool. Understanding of polar patterns increases the quality of recording and allows for more streamlined production. Therefore it is imperative that all audio professionals understand this vital concept.

References

https://www.e-av.co.uk/Downloads/Polar%20Patterns.pdf

http://www.shure.co.uk/support_download/educational_content/microphones-basics/microphone_polar_patterns

Images

http://www.earthworksaudio.com/wp-content/uploads/2014/04/00ARROW_earthworks_omni_layers.png

http://www.lennonbus.org/index.php?/blog/posts/infoblog_-_microphone_pickup_patterns1/

http://www.harmonycentral.com/articles/what-you-need-to-know-about-microphone-polar-patterns

http://www.lennonbus.org/index.php?/blog/posts/infoblog_-_microphone_pickup_patterns1/