 Thus the E82CC was a long-life version of the ECC82 intended for computer and general signal use, and the E88CC a high quality version of the ECC88/6DJ8.While the E80F pentode was a high quality development of the EF80, they were not pin-compatible and could not be interchanged without rewiring the socket (the E80F is commonly sought after as a high quality replacement for the similar EF86 type in guitar amplifiers).The letters "CC" indicated the two triodes and the "F", the single pentode inside these types.