AT THE END of the day, it really doesn’t matter how good a guitarist you are if the instrument you’re holding isn’t in tune. Only a handful of players have made a living wrestling guitars back into pitch without putting so much as a foot wrong over the years — Jeff Beck arguably being among the finest, considering how much abuse his whammy bar gets on any given night. But for the rest of us mortals, those chords, riffs and leads are just not going to sing as well as they could — or, indeed, as well as they should — if our tuning isn’t as close to perfect as humanly possible.
There have been all sorts of components invented and reinvented for the guitar to help combat slippage, from locking machine heads and specialist nuts to machines that do the hard work for you, as demonstrated by the robot tuners that controversially became a standard feature for Les Pauls briefly in 2015. External and removable devices, however, such
