The ALTER 500 is a FET compressor built in the 500 standard. The FET-type solution was used for the first its application in the legendary UREI 1176 compressor from the 70s. The ALTER is a single-channel unit with stepped input and output controls. The Ratio switch has six positions, including two additional to the original 1176 1:1 and 2:1 settings. Slam Mode can be turned on with a separate switch, working regardless of the Ratio settings. Attack and release times can be set to Fast / Mid / Slow with 3-pole switches.