Tube location info: The Balanced Gold Pin ECC83S is located in V6 closest to the power tubes and the standard Gold Pin ECC81 is located in V4.All Combo amp Retube Kits are shipped with the Eurotubes Double Mica 6L6GC’s at no extra charge. JJ Electronic started building us a proprietary version of their 6L6GC (the 6L6GC-DM) in 2005 with extra layers of mica. This reinforces the plate structure and all but eliminates tube rattle symptoms.