It is widely known that the LA-2A unique character is a result of the applied T4B photocell.
In the original TELETRONIX design, an electroluminescent panel provided a light source for the photo resistors. This component was very variable in parameters, and this affected the result compression and stereo image of the audio.
IGS Audio has developed a new photocell parallel to the T4BX. By precisely selecting, testing and matching subcomponents used in the assembly of this photocell they have created a product line consisting of nearly identical devices in parameters and sound.
All IGS Audio optocompressors (ONE LA500 and One Leveling Amplifier) are equipped with this T4Bx photocell. It is, of course, interchangeable with the original Teletronix T4B so you can experiment and perform your own test.