Hello Calle Jr. These are from 2005 with kt 90 from factory, here you can also set in 6550 without problems. After two weeks playing with the original kt 88 from Jadis, bias was too high, they burn out after 30 hours already, the Dutch importer has bias decreases but problem with all brands was 88 kt at 1500 hours is 50% lot and the rest is worn. The 120 kt is deployed without the bias is increased, is possible (this tube is much more power than a kt 90) And this is the most beautiful sound that my wife and I find we have ever received from a tube.
The transformer,s of the ja 80 are themselves less hot with the 120 kt, no matter what and how old the ja 80 is, the transformer is more than heavy enough for the 120 kt.
The transformer,s of the ja 80 are themselves less hot with the 120 kt, no matter what and how old the ja 80 is, the transformer is more than heavy enough for the 120 kt.