Tube Rolling; 5U4G; 6Sh7; 300B - ANK 300B Construction Manual

13.3 Tube Rolling

We feel that the sound of the ANK Audio Kits Interstage Monoblock 300B SET Amplifier is truly
sublime and that is destined to become a popular kit. It provides a highly detailed and transparent
presentation with gorgeous sonics. Rolling some quality new production tubes and/or some nice NOS
tubes will allow you to tailor the sound to your particular preferences.
13.3.1 5U4G(B)
The directly heated 5U4G(B) full-wave rectifier is a 1930s design and there are classic era NOS
5U4G(B) tubes available at reasonable prices. Of course, audio lore is that the one to have is the 274A
or 274B Western Electric rectifier, if you can find one and have $1,000 or so burning a hole in your
In any case, do not substitute any other 5V rectifier for the 5U4G(B) type for which this
pocket.
amplifier was designed; there are some significant differences between a 5U4G(B) and other
rectifiers, with respect to voltage drop and current specifications, and the result of a substitution is
unpredictable and could damage your amplifier.

13.3.2 6SH7

NOS sharp cut-off 6SH7 (driver) pentodes are readily available at very affordable prices from many
tube suppliers. The 6SH7 comes in a glass tube version or with a black metal case; both tube types
sound very good.

13.3.3 300B

The directly-heated 300B power triode is in current production and available at various prices. NOS
tubes are quite rare and prices can be astronomical.
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