All the talk of 12AU7s I thought I'd share my opinion on the stack that I've rolled lately, almost more than I paid for the 6A second-hand
. This is all with SE KT88s in UL mode with ZMF Calderas on Low impedance.
So far:
- Amperex 7316 - probably my favourite (and most expensive) of the lot, insanely musical, punchy, best staging out of all the other tubes, good extension and clean treble up top, if a little rolled off. Pretty hard to find though and it cost a lot! The best balanced tube out of the lot and I simply leave them in without rolling anymore.
- Tesla ECC802S - a good foil to the Amperex for a more neutral sound. It's how I felt the TF ECC82 should have sounded with better PRAT. They're meant to be a Czech copy of the TF ECC802S which are too rare to buy nowadays.
- Philips E80CC - similar to the 7316, but a bit darker and doesn't do the technicals as well
- Amperex (Valvo) 12AU7 - similar to the 7316, but I found them a bit too lean and felt the mids sounded a little odd. 7316 were better in every way.
- Mullard CV491 (14mm short plates) - random find from Langrex for pretty good $, I don't have CV4003s to compare with anymore. Personally a bit too rich and warm for me, but the mids were glorious and I can see how it would work in some setups and tastes.
- Telefunken ECC82 - I felt they were bland and boring, never really lifted me
- Siemens ECC82 - too bright for my setup, but the technicals were good
I've got some Tungsram ECC82s coming shortly.