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.


After scoring two top 10 singles ( "I Get Off" and "It's Not You" ) from their self-titled debut and touring steadily for two years with acts as diverse as Shinedown, Stone Sour, Disturbed, Megadeth, Papa Roach, Godsmack and countless others, Pennsylvania quartet Halestorm are back with their second full-length, The Strange Case of hellip . Musically diverse and emotionally revealing, the album resonates with a newfound poignancy that takes Halestorm to a new level of creative achievement. "I was extremely proud of Halestorm when we released it, and I still love it, but I think I was using mostly one musical technique throughout," explains frontwoman Lzzy Hale. "We were on'ten,'and we blew through the songs in a safe way ndash or as safe as something that goes,'I get off on you getting off on me'can be. This new record demonstrates more depth and heart. It's a lot more expressive and really lets down the barriers." Halestorm started writing for the new record while they were on the roa...

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