Tube location info: The Balanced ECC81 is located in V6 closest to the power tubes and the two high gain ECC83S's are located in V2 and V3. The standard ECC81 is located in V9.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.