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Hi, my first post here!
I have just got a TLA 5051, and after replacing cheap Chinese 12ax7's (ecc83) for electro harmonix (Russian) ones, I am curious to know whether I can replace with ecc88's, as I hear these are nicer, and i have some amperex ones from holland, but do they have a different grounding pin config, and will this be bad for the 5051? The reason I ask, is although I have read up a lot recently about the difference between the valves, when I changed the valve (ecc83) from my RODE K2, to the advised, 6922 (ecc88) there wasn't a problem.. Yet there seems to be an advisory against using ecc88's instead of ecc83's .. Many thanks, for any light shed upon this.


Boswell Mon, 03/26/2012 - 04:17

They are not a direct replacement as (at the very least) the heaters are wired differently. The ECC83s have a 12.6V @ .15A heater wired between pins 4 and 5, but centre-tapped at pin 9, so by wiring 4 and 5 together you can supply the heater with 6.3V @ .3A between this point and pin 9. The E88CC has a 6.3V @ .3A heater on pins 4 and 5 with pin 9 being a grounded screen.

I don't know how you had an ECC83 working in a Rode K2 as it's wired for the 6922/ECC88/E88CC. Here's a recent thread on that subject.


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