I normally try to mention free plugins that are available for both Mac and PC, but Variety Of Sound’s Thrillseeker VBL is such a great plugin that I just had to let you know about it.
Thrillseeker VBL is an emulation of a “vintage broadcast limiter” following the classic Variable-Mu design principles from the early 1950′s. They were used to prevent audio overshoots by managing sudden signals changes. It offers an incredibly authentic audio transformer simulation which not only models the typical low-end harmonic distortion but also all the frequency and load dependent subtleties occurring in a transformer coupled tube circuit, and which add up to that typical mojo we know from the analog classics.
If your on PC and use the VST format, then this one is a definite download. Windows x32 is needed.