Vactrol based compression circuit
The 'Punch' circuit is a J-FET Harmonic Enhancer that adds even-order harmonic distortion for a fuller, "punchier" tone while taming nasty peaks that may escape the Vactrol. The Grit circuit adds frequency-dependent signal distortion to make any track truly stand out. This is a highly creative effect that can work especially well on drums and percussion, solo brasses and woodwinds and even vocals when added presence and position in a mix is required. Bypassing both 'Punch' and 'Grit' circuits delivers the purest Opto-compressor tone, perfect for critical solo instruments and clean vocals. 'Punch' and 'Grit' circuits can even be combined for additional tone shaping options.
https://artproaudio.com/product/vla-500-art-500-series-compressor/
