Has anyone compared 6J5 to 6J5GT and 7A4's , different tube strutures are more microphonic than others . I just ordered a few 6J5GT's to compare to the metal ones which are almost coming out my ears .
I also bought several 7A4's and 7B4's that i found for less than $3.00 each The 7A4 is the same as the 6J5 electricly but has a locktal base , and the 7B4 is a 6SF5 but is pin for pin exchangible with the 7A4 .
Will be building some from scratch amps and can use any preamp tubes i want , also laid in some 7F7 NOS at 4$ each alot cheeper than the 6SL7's are going for .