Low-gain tube used in very early Fender amps. Can sub for a 12AX7 to lower gain and produce a slightly warmer tone. Great for harp or blues where softer, more compressed distortion at lower volumes is desired. Medium/soft gain.
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 ampï¾’s bias whenever changing your tube type or rating number.
