https://reverb.com/item/40748989-bo...p-head-with-class-a-ab-switch-mm-transformersThis is a Vintage 1998 Bogner 101b with class A/AB factory option. This is the era that Bogner used Mercury Magnetic Transformers - Best sounding IMHO and best made. Amp is my baby - Comes with new Tube amp Doctor TAD EL34's maybe 5 hrs. on them. Everything works 100% no worries see my feedback.