Single ended triode (SET) amplifiers have a long standing reputation of subjectivly providing the highest fidelity amplification. However, while they capitalize on circuit simplicity, there are many practical problems with implementation – they are heavy, have very low efficiency resulting in a lot of excess heat being produced, relatively low output power, and can be made with only a limited number of tube types which are usually driven to the edge for maximum power, hence a short life.
As the saying goes, only a fool keeps doing the same thing expecting different results. There are many approaches to improve the technology, which are rarely used, mostly because they do not fit the established set of topologies and parts. In times past, there were about 7000 types of tubes and many variations of the basic types freely available. For many years we have searched for the optimum tube that fits the rarely used approaches to single ended triode amplifier designs – one that would not require very high voltage power supplies, had high gain so that class A2 operation is feasible to get higher power and effieciency, does not require extraordinary transformers, so could fit a smaller and lighter form factor – AND, last a very long time.
Kinesis is the result of our search. It is a dual Triode SE class A2 amplifier, it's two channels operate two tubes in parallel to provide 40W per channel, and be connected for single channel operation with 80W of output. The wideband transformers extend full power bandwidth an octave above and below the full audio band. Input stages are fully balanced for either balanced XLR or unbalanced RCA input. Total thermal efficiency is about 22%, which is almost double that of a typical triode SE amplifier, and the tube life is well over 20000h.
