This is the result of over two years of experimenting and research to attain the cleanest most natural sounding single ended amplifier I can achieve with these tubes, the 6SL7 and the 6L6GC. This circuit uses the 6SL7 for its outstanding linearity. The circuit is a cathode follower connected to a common cathode amplifier for the first stage, so one can have better isolation between the channels. Before inverse feedback the amplifier produces 50-30,000 Hertz, with about 6% THD (of the so called sweet even order harmonics). The amlifier achieves this by virtue of the direct connected cathode follower design. With NFB the range extends from below 20 to over 50,000 hertz, with less than 2 percent THD. The amplifier uses 2% metal film resistors and orange drop capacitors. output transformers are used for the best sound possible.
While many make the claim that nothing beats the sound of a triode output, I believe that the circuit overall is what really counts. The other factor I my mind is enough power to drive the speakers satisfactorily so as to maintain a good affect for listening to a wide range of music, not just acoustic instruments and voice. So if one wants sufficient power and the cleanness of class A amplification, this is the way to go.
Using the 6L6GC from JJ/Tesla affords
one another benefit: high power on a budget. The JJ/Tesla 6L6 is a beam
power tetrode designed to overcome the quirky characteristics of regular
tetrodes while giving a higher and more efficient power output. And being
a JJ/Tesla you know you are getting a sweet sounding output tube. The 6SL7
in this amplifier is the Phillips JAN 6SL7. This tube right out of the
box has the most natural widest range sound I have heard from a test of
four different types: Sylvania, RCA, Sovtek, and the Phillips. So this
is the preamp/driver of choice.