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.

Kenny Wayne Shepherd

There are few artists whose names are synonymous with one instrument and how it's played in service to an entire genre. Utter the phrase "young blues guitarist" within earshot of anyone with even a cursory knowledge of the modern musical vanguard and the first name they are most likely to respond with will be Kenny Wayne Shepherd. Still barely in his 30s, the Louisiana born axeman and songsmith has been selling millions of albums, throwing singles into the Top 10, shining a light on the rich blues of the past and forging ahead with his own modern twist on a classic sound he has embodied since his teens. He met Stevie Ray Vaughan at 7, shared the stage with New Orleans legend Bryan Lee at13. As an adult, he continues to create genre-defining blues-infused rock n' roll. Kenny Wayne Shepherd's How I Go not only serves as a strong reminder of the chops that caused Guitar World to place him right behind B.B. King and Eric Clapton on their list of blues guitarists, but it's the strongest ind...

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