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.

Miss May I

Album titles can be quite a dicey proposition. In a perfect world, the title should tell you something about what kind of action awaits inside the jewel box (or the album jacket). There's not much room for error when you pick up Slayer's Reign In Blood or Katy Perry's Teenage Dream you pretty much know what you're getting into, either way. Which is why you should pay close attention to the title of the new album from modern metal mavericks Miss May I. The band may have recorded in a studio, but the title At Heart tells you everything you need to know about where those songs actually came from. "I feel like there are a lot of ways for a metal band to sound played-out," offers Miss May I frontman Levi Benton. "One of the biggest ways is the whole'hate'thing. It bums me out when I'm listening to a band I like and the lyrics are along the lines of'I hate you.'They're doing what every other metal band in the world are doing by cheesing it up like that. On At Heart, we wrote about things per...

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