Many folks who buy our tubes know that we use a special process to categorically rate our tubes so that players can select the tubes that best fit their preferred tones and styles. However, we get a lot of questions about our rating system, and what the numbers actually mean.

IMPORTANT BIAS NOTE: If you're replacing a tube with the SAME TYPE of Groove Tube (tube model and rating), you do not have to rebias your amp. In any other case, you should always have a qualified amp tech reset your amp’s bias whenever changing your tube type or rating number.



Early distortion, wide range, softer attack good for Rock and Blues solos.



Normal performance, great dynamic range/attack and best all around rating type for all styles of playing



Most dynamic range, most clean power/less break-up for power players, Jazz and bass amps.

Roger Waters Band

David Kilminster: In 1991 Dave won the European 'Guitarist of the Year' competition, and shortly after started writing transcribing recording for 'Guitar Techniques' magazine... as well as teaching at the Guitar Institute (in Acton, London... not LA!!)... He later went on to teach guitar at the ACM in Guildford. During this time he got a job with John Wetton (Asia, UK, King Crimson, etc) singing and playing guitar, and after several tours with the John Wetton Band they got together with Carl Palmer (the 'P' in ELP) and formed a band called Qango... He spent a short while playing and touring with Ken Hensley, until he joined forces with one of his musical heroes, Keith Emerson (ELP)... and toured and played guitar, firstly with 'the Nice' and then later as the Keith Emerson band, where Dave also took on lead vocal duties. Then six years ago Dave auditioned for Roger Waters, and subsequently played guitar (and sang some lead vocals too!!) on the 'Dark Side of the Moon' tour, which lasted...

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