Groove Tubes Gold Series GT-6L6-S Matched Power Tubes Medium (4-7 GT Rating) Duet guitar amp tubes are Slovakian-made with high power and very aggressive dynamic tone...punchy, but still sweet. New GT design with more power and heavy duty components. High power type with more highs and lows than other 6L6 types.

Country of origin: Slovakia

Low-rated tubes have early break-up and distortion, wide range and softer attack good for rock and blues solos. Medium-rated tubes offer normal performance, great dynamic range/attack and are the best all around rating type for all styles of playing. High-rated tubes have the most dynamic range and the most clean power/less break-up for power players, jazz guitarists and bass amps.