TUBE REPLACEMENTS
The MV45A/MV75A amplifiers each use seven vacuum tubes of three different
types. Each type has been carefully chosen for its circuit application. It is well known
that tubes of a given type vary sonically depending on the manufacturer. We have
chosen the brands of tubes that we supply based on extensive auditioning of available
brands. The choice of brand has been made solely on the basis of sonic performance
and reliability without regard to either cost or prestige.
We know of no vacuum
tubes available which will improve the sonic performance of your conrad-johnson
amplifier. Also, the tubes in your amplifier have been tempered by a controlled burn-
in procedure that permits them to perform for a greatly extended period without sonic
degradation. We anticipate one to two years of operation without degradation in
normal use. We highly recommend that, when the time comes to replace the vacuum
tubes, you purchase replacement tube sets from conrad-johnson design.
These amplifiers have been designed to make tube replacement as simple as possible.
Because the output tubes are individually biased, replacement tubes need not be
matched pairs. No a-c balance adjustment is necessary. It is necessary to re-bias the
amplifier when the output tubes are replaced. Your amplifier has built in bias
indicators so that no instruments are required to make this adjustment.
