Cakewalk has made the CA-2A (their emulation of the legendary Teletronix LA-2A Leveling Amplifier) available as a free download via their free Command Center software, also available on their website. If you don’t already have a Cakewalk user account, I can assure you that signup is a breeze. A lot of people worked very hard to create the CA-2A, so hopefully the small amount of time it will take you to install the Command Center software and download it for free isn’t a complete deal breaker.
Invented by James F. Lawrence II (founder of the Teletronix Engineering Company) and distributed by Studio Electronics two years after acquiring the Teletronix brand in 1969, the LA-2A Leveling Amplifier was a tube-based compressor that applied gain reduction with an electro-luminescent panel combined with a cadmium-sulfide light-dependent resistor…known as the “T4 Circuit”.
This was one of the first “program dependent” designs; unlike common compressors with attack, release and ratio controls at fixed values, a program dependent compressor will adjust the attack, release and ratio depending on the frequency and amplitude of the incoming signal. So now you don’t have to be confused the next time you hear the term “frequency dependent compression ratio”.
The CA-2A “T-Type” Leveling Amplifier is modeled after the T4 optical photocell with a fixed attack time of ten milliseconds and a program dependent release time varying between 0.5 to 5 seconds. It also has a (here it comes) frequency dependent compression ratio, with Total Harmonic Distortion (THD) that adds even and odd harmonics in order to recreate the analog characteristics of the original hardware.
A toggle switch on the front panel switches between Limiter and Compressor modes. In Limiter mode, the frequency dependent compression ratio (there it is again) becomes significantly increased, ranging from 4:1 to 20:1… which will obviously produce a noticeable amount of distortion.
The “R37” knob will adjust the gain reduction frequency response, attenuating frequencies above 1 kHz in the “HF” position, while attenuating all frequencies equally in the “Flat” position. This parameter is often used to reduce sibilance in vocal recordings. Although you can also use it to iron out a good balance between low and high frequencies in Limiter mode.
The rest of the controls are relatively self-explanatory, though there are a few hidden surprises lurking about the interface, such as additional options available in a context menu for “External Sidechain” and “Photocell Memory” modes, the “Fast Reset” mode being considerably less sluggish than “Classic Mode”. Also, there are four “VU Meter Modes” that determine how you monitor output level and gain reduction.
The CA-2A Leveling Amplifier is obviously a very popular choice for mastering vocals, and by itself is ideal for material that calls for a more conservative use of compression. There are noticeable gain spikes when processing audio with sharp transients in high gain situations, but if you don’t mind placing a limiter at the end of the signal chain, you can really fatten up pretty much anything you feed through it.
CA-2A Leveling Amplifier is available for free download via Cakewalk in AU, AAX and VST3 for Mac, and AAX, VST2 and VST3 (32-bit and 64-bit) plugin format for Windows.