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.

low

1-3

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

Medium

4-7

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

High

8-10

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

Brent Mason

Brent Mason is one of the most recorded guitarists in history. As well as being a Grammy Award winning artist he is also 14 times winner of the Academy of Country Music, the CMA (being nominated every year since 1991), a NAMMIE winner and for many years has won the annual Music City Allstars Award (the musician that has played on most songs on the radio in respect of the top ten for the entire year). Not only can he be heard on a high proportion of the country Top 10 at any given time, his playing can also be heard on countless TV commercials, film sound tracks and television scores. His technique and the theoretical approach to his style have been studied extensively from places as diverse as the Berklee College of Musicand countless internet forums and online lessons. Although currently his name is synonymous with Country Music (a result of appearing on so many records in this genre), Brent, in reality, is a virtuoso musician who is more at home playing jazz, classical, Latin, swing,...

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