LA-2A Compressor
From WikiRecording
The Teletronix LA-2A uses Electro-Optical Tube Compression. It is one of the most common and well regarded compressors in top of the line studios, and recordings. The LA-2A has incredibly low noise, and also has an incredibly flat freq response of .1 db between 30-15000hz. It was originally patented by Jim Lawrence.
Settings and Configuration:
The LA-2A has a Threshold control that is refered to as "Peak Reduction" after the desired compression is set, adjust the "Gain" control to match the desired output level.
The VU meter shows signal level either at 4 db when the switch is turned to the left, or 10db when the switch is turned to the right, when it is in the middle the VU meter displays gain reduction (the amount of reduction in DB effected on the incoming signal).
The LA-2A has either a high or low ratio setting simply listed as "Compress" or "Limit" the Compress setting has a lower ratio and has a gentler curve than the Limit setting.
The LA-2A uses an Electro-Optical cell called the T4 to determine both the level of the signal and to control the gain. The T4 consists of a Photo-Electric cell and electro-luminescent panel. Basically a light and a panel that reads the level of light.
The Attack and Release cannot be modified unlike some other compressors, the Attack is set to 10 microseconds and the Release is 40-80ms for 50% release; 0.5 to 5 seconds for complete release
How it works:
The LA-2A photo-cell has a "memory" which acts as the compressors release, the cell after removing signal or light, reduces its resistance and relative compression by half after the first 40-80ms, after that it can last up to a few seconds.
Tip:It can work well to patch an 1176 into a LA-2A on vocals.
Also known as the Teletronix LA2A or LA 2A.
This photo is of the LA-2A at Abbey Road Recording Studios, London, behind the desk in Studio 3.
