This tube has a distortion that is between a 6L6GC and a 6550A. In older Marshall's that have 6550's, this tube will give you more compression and distortion at lower levels than the other 6550 offerings.
This tube is terrific in Class A amps such as the GT Solo Single when you want to have a lot of output for smaller live venues.
Many people prefer these in some Marshall amps where more clean headroom and output is desired.
Groove Tubes GT-6550-C QUARTET (code 55068)
Guitar Amplifier Tube, Softer Version of the Older USA 6550A
£162.46 (inc vat)