NOS KT 88s or GE 6550s

I've been told that the transformer would get into trouble sooner than later if the KT120s were incompatible somehow...but my informal research results remain: Happy KT120 users in the thousands, reported transformer deaths 0. It will be a sad day when all these overworked transformers give it up. I do like the Tung Sol 6550s that came with my amp and I swap 'em in when I'm bored or have a need to burn my fingers, and I also have a set of Sovtek KT88s that sound fine but lack the groovy gold lettering of the Gold Lions, so there's that. I understand the gold lettering makes them sound 13% better than otherwise.

Pradeep, I haven't heard the NOS JAN 6550A...were these GE's as well and just Joint Army/Navy or ?? I do own a matched quad set of GE 6550's that are like new, and once my SED 6550 C's give up the ghost will replace them with the GE's. You have to be VERY careful that the GE's you will be receiving will still be good. I have heard several horror stories about supposed NOS GE's going up in smoke. I had this happen on my amp when I first acquired it, however, I knew that the tubes were very old and it was a matter of time before ..poof. Happened almost immediately after I acquired the amp...luckily no other damage except to the tube itself.

I don't know what all the fascination is about with the GE 6550's. I always remember them to be just okay and had issues with them in Dynaco Mklll's so i never used them. Later versions of the tube had major issues with high plate voltages or high bias currents hence the Dynaco issues. For that matter so did the Genelex KT-88 as they would routinely arc and blow the fuse. I much preferred the Philips Sylvania 6550 that Audio Research used for many years. An excellent tube and much more robust than the GE IMO. The Sylvania was a smaller tube than the GE.

Daveyf
The Singapore dealer (Well Audio Lab) tells me there is no difference between the GE and Jan 6550s.
Njoy
Pradeep

Hifigeek1,

So much of it comes down to the circuit we're using the tube in and our personal preferences. Some is just blind luck in terms of getting a good or bad batch. I have both the ST-shaped and the straight-sided Philips Sylvania 6550's and they are very nice tubes, I agree. I prefer the ST-shaped but again, that's just my opinion.