We were the first company in the US to use that tube (in our Novacron amplifier, about 1991).
You are correct- the tube stopped production about 1999 when the plant making it went offline and was torn down. There do seem to be large numbers of them available though.
We used them in an OTL as that is what we make- the tube itself is good at this task, being capable of high current, good linearity and operating at a low plate (B+) voltage. Its primary weakness is that it was designed for an American Septar tube socket that is overloaded by the filament circuit of the tube. For this reason it eats tube sockets. The best sockets we have found for the tube so far are ceramic.
The sheet metal has to be designed to allow the socket to cool properly. If this is not done the socket will have a very short life (and possibly the associated wiring as well); less then 1000 hours. Longer life comes with proper design but in all cases eventual socket replacement will be required.
Its tricky to compare it to a tube like the 300b due to the fact that the output transformer is an enormous variable in tube operation- and in particular single-ended operation. I would say it sounds every bit as good (we built an OTL using 300bs as well) but its a lot trickier to build an OPT (OutPut Transformer) for it due to the lower plate voltages, higher plate currents and the higher power levels. So actually auditioning the differences is tricky as well. However in our experience it has a very detailed, smooth and robust character.
Of course, we think that an OTL is the preferred embodiment; single-ended aficionados will tell you that single-ended is the way to go, and so on. So I would not worry about that bit of it.
You are correct- the tube stopped production about 1999 when the plant making it went offline and was torn down. There do seem to be large numbers of them available though.
We used them in an OTL as that is what we make- the tube itself is good at this task, being capable of high current, good linearity and operating at a low plate (B+) voltage. Its primary weakness is that it was designed for an American Septar tube socket that is overloaded by the filament circuit of the tube. For this reason it eats tube sockets. The best sockets we have found for the tube so far are ceramic.
The sheet metal has to be designed to allow the socket to cool properly. If this is not done the socket will have a very short life (and possibly the associated wiring as well); less then 1000 hours. Longer life comes with proper design but in all cases eventual socket replacement will be required.
Its tricky to compare it to a tube like the 300b due to the fact that the output transformer is an enormous variable in tube operation- and in particular single-ended operation. I would say it sounds every bit as good (we built an OTL using 300bs as well) but its a lot trickier to build an OPT (OutPut Transformer) for it due to the lower plate voltages, higher plate currents and the higher power levels. So actually auditioning the differences is tricky as well. However in our experience it has a very detailed, smooth and robust character.
Of course, we think that an OTL is the preferred embodiment; single-ended aficionados will tell you that single-ended is the way to go, and so on. So I would not worry about that bit of it.