In the words of Old Blood Noise Endeavors:

Old Blood Noise is now offering a harmonic take on their as a full member of the OBNE roster. The Blackcap retains the analog tremolo side of the original and takes the highly functional digital tap side into the realm of harmonic tremolo. Where before it turned your volume up and down, now it crossfades between your highs and lows. Mixed in parallel or series with the amplitude modulating tremolo, its a new aural experience.