Positive Grid LA Comp pedal is a compressor pedal available under the Comp effect group and is inspired by Teletronix LA-2A Compressor.
The LA Comp pedal has simple controls: a Peak-Reduction knob controls the gain of the side-chain circuit, and therefore, the gain reduction; a Gain Control for make-up gain; and a Limit/Compress switch which alters the compression ratio.
According to Universal AudioFor over 50 years the Teletronix LA-2A has been revered for its smooth, natural, musical compression. WIth its unique tube-driven electro-optical attenuator system that allows instantaneous gain reduction with no increase in harmonic distortion, the LA-2A massages signals like no other compressor ever made.
The LA-2A was invented by James F. Lawrence II, founder of the Teletronix Engineering Company in Pasadena, California in the early 1960s. The LA-2A had evolved from Lawrence's first leveling amplifier, the LA-1, which was favored by Gene Autry, and its successor, the LA-2, which had been adopted by CBS and RCA. In 1965, Lawrence sold Teletronix to Babcock Electronics of Costa Mesa, California, and in 1967 Bill Putnam's company Studio Electronics (eventually renamed UREI), acquired Babcock's broadcast division, including the Teletronix brand. 
Three versions of the LA-2A were made until 1969.
After Universal Audio was re-established in 1999, the company re-issued an updated version of the LA-2A.
The LA-2A is a hand-wired, tube-based compressor. It uses an electroluminescent panel together with a cadmium-sulfide light dependent resistor to provide gain reduction, which in the LA-2A's own terminology is called the T4 cell. The properties of the T4 give the LA-2A its unique character by making it an entirely program dependent design. The average attack time is 10 milliseconds, while the release time is about 60 ms for 50% release and 0.5 to 5 seconds for full release, depending on the previous program material.
The LA-2A has simple controls: a Peak-Reduction knob controls the gain of the side-chain circuit, and therefore, the gain reduction; a Gain Control for make-up gain; and a Limit/Compress switch which alters the compression ratio. The VU meter may also be switched to show the gain reduction or output level.
The LA-2A has a sonic character that makes it sought after by many recording engineers.
LA-2As warm things up. ...they EQ all the warmth and low mids and bass. When you put bass and drums in them they get fatter and bigger. And unless you hit them way hard and make the tubes sizzle they don't really distort.— Jim Scott
- The LA-3A, a transistorised version of the LA-2A
- The 1176 Peak Limiter, another popular vintage compressor descended from the LA-2A
- Fuston, Lynn. "A History of the Teletronix LA-2A Leveling Amplifier". Universal Audio. Universal Audio.
- "LA-2A Manual" (PDF). Archived from the original (PDF) on 2006-11-13. Retrieved 2009-03-11.
- Cooper, Michael. "Universal Audio LA-2A". Mix. Future Plc. Retrieved 10 September 2021.
- JBL vintage service manuals. UREI LA-2A service manual. "This Instruction Book was reprinted from text composed by the original manufacturer (complete with errors and exaggerations; for example, the specification for attack time should have been in milliseconds rather than microseconds." Retrieved on October 11, 2009.
- "Top 20 Best Compressors of All Time". Attack Magazine. Attack Magazine. Retrieved 10 September 2021.
- "Archived copy". Archived from the original on 2008-09-27. Retrieved 2008-08-25.CS1 maint: archived copy as title (link)