My modest collection of classic AR's includes three pairs from the 4 series: two pairs of 4x's and one pair of 4's, and even with all that I've learned by reading posts on this site and performing surgery on my speakers, I am still looking for more information and further opinions. 1. Capacitors. My early S/N AR-4's have been restored (pot restoration, re-cap, re-dope, cabinet refinish), including original wax cap replaced with 6 mf Erse Pulse-X caps. These speakers sound terrific. See pic 1 for