The Groove Tubes Silver Series ST-7591-R Power Tube is a somewhat obscure pentode tube used in some early Gibson amps that had been off the market. Recently, a Russian factory decided to supply it again. Groove Tubes ST-7591-R tubes are made in very low quantities and are a close copy of the original vacuum tube.

Groove Tube Silver Series ST-7591-R Power Tube Features:

• NEW SILVER SERIES TUBES
  
  Groove Tubes Silver Series are tested and warranted to meet or exceed factory specifications.
  
  Silver Series tubes are excellent for "normal" tube replacement applications and offer exceptional value.
  
  Not recommended for the critical high gain V1 stages of high gain guitar amps, but perfect for the other less critical stages such as V2-V6 stages.

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