It's called Div by 13 JJN50-Half I am assuming by the name is the JJN50-100 but in the half power or 50watt mode. If you play classic rock or are looking for that 70' Marshall tone, this is a good amp profile to try out. In one of the bands I play in, the guy has the AMW39 which is bascially the younger brother of this amp. El34 marshall tone that is tube rectified. We set up his amp, suhr Sl67(plexi amp) and his marshall JCM800. The divided by 13 seems to sit right in between a plexi and jcm800. Doesn't seem to have that harsh brittleness that some JCM800's have on the top end. This profile sounded really nice with my R9. I raised the gain by 1 LED. check it out if you like 70's Marshall tones.