E88CC

The E88CC is the European professional designation for the 6922, manufactured to the Philips special-quality standard with gold pins and stringent testing. It is functionally identical to the 6922 but the E88CC designation specifically denotes manufacture to the Philips internal quality protocol, which guaranteed tighter section matching and lower noise. In practice, a 6922 and E88CC from the same factory and era are the same tube; the distinction matters primarily for provenance and collector grading. The designation appears most commonly on Philips Heerlen, Mullard Mitcham, and Siemens Munich production.