Some time ago, the Japanese company Leben had a brief flurry of activity in the UK’s online community. The company’s CS 300X integrated amplifier was suddenly the darling of the forums. As many have learned to their cost, this usually means a tiny number of products bought second-hand and resold time and again around that community until every box-swapper has tried it. They moved on, but Leben is back… and the company’s latest CS 300F integrated amplifier marks that return.
Depending on your viewpoint, Leben makes evergreen audio products that have a timeless classic appeal, or it makes retro products that call upon the designs of a bygone age. It doesn’t really matter either way, but no-one’s going to buy the Leben if they are a fan of 1980s-style matt-black minimalism or garish excess; the look and feel of the CS 300F – as with all Leben models – is very much from the Golden Age of stereo. With its Canadian white ash side cheeks – used for ‘baseball bats and oars for low boats’, apparently – brushed gold knobs and dials and matching front and rear panels (with green accent for the product details), the CS 300F looks about as 1960s as Mini Coopers and Mini Skirts.
The CS 300F may look classically conventional, but this all-valve design uses some distinctly non-standard toobs. Where most designs (including Leben’s own CS 300X(S) model) might use something like two pairs of EL84s as power output tubes to achieve its modest-yet-meaty 15W per channel, the CS 300F uses two pairs of JAN 6197/6CL6 valves made by General Electric. This power pentode valve from 1954 was a dual-use design; although it was made to be used as a Class A amplifier valve, its primary use was in early digital computers, as it was designed to be robust enough to survive being switched between full operation and cut-off. In fact, the prefix ‘JAN’ comes from ‘Joint Army/Navy’, so the JAN 6197 was intended for Cold War military computational use. Because it is considered a computer valve, its use in an audio capacity was all but overlooked, but the joy of this valve in audio is its linearity and reliability. Leben invested in large numbers of NOS (new, old stock) JAN 6197 valves because there are no modern aftermarket models available. The two double triode driver valves are from a more conventional provenance; they are Hitachi 17EW8. This high-gain radio tube was also known as the HCC85 and was also produced by RCA and Mullard. As with the JAN 6197, it’s not in current production and Leben has stockpiled NOS Hitachi valves for users. The amplifier is fully self-biasing.