Since I have recently bought some very nice EL34/6CA7 integrated amplifier (serbian manufacturer P&K Audio, model Duet 34, triode mode connection only), I started playing with its one and only input pre-amplifier tube that is of ECC81 type. Other two phase inverter/driver tubes are the reference Tungsols 5687 which I luckily did not have to play with 🙂
In the output tube section, I tried both Mullard EL34 reissue and settled with quartet of EH 6CA7 tubes which produces some extra bass output. So, I needed some ECC81 tubes to additionally open up mid and high range frequencies to some reasonable margin…
So, I started with some classic Philips ECC81 tubes but the result was not so good, lots of bass without mid and high joy. Then bingo, I found one precious Sylvania 12AT7 Black Plates 3 Mica which sounded more than fantastic! Also, I tried Sylvania 12AT7 Gray Plates 3 Mica and Black plates with 2 Mica but they sounded significantly muddier and not so refined and 3D like the Black plates 3 Micas… Tried some Siemens, Tungsram`s, RCA`s, RFT`s but none of these tubes satisfied my taste.
Then I decided to try Radio Technique 12AT7, Grey plates, 2 Mica with copper grids. All what I can say is WOW! Detail, detail and detail – that`s everything to say about it! They rivaled Sylvania Black plates 3 Mica in almost all segments. They have wonderful midrange and especially bass-to-midrange area, something more pronounced bass in comparison to Sylvanias but even better defined treble frequencies. 3D feeling is here with this tube too but it has rather meatier sound than Sylvanias Black plate in general. Soundstage width opened up significantly while retaining very good depth level. All in all, this is an excellent tube which is more than HIGHLY RECOMMENDED!
I also ordered one Sylvania JHS Grey plates 2 Mica from TubeMaze`s review so I can`t wait to compare it to RT.