V
ACUUM TUBE REPLACEMENT
Each channel of the Evolution 20 uses five vacuum tubes: one 6CW4
and four 6GK5s. Each type has been carefully chosen for its particular
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 we supply based on extensive auditioning of available brands
with the choices being made solely on the basis of sonic performance
without regard for either cost or prestige. We know of no vacuum tubes
available which will improve the sonic performance of your Evolution 20.
In addition, the tubes in your preamplifier have been tempered by a
controlled burn-in procedure that permits them to perform for a greatly
extended period without sonic degradation. We anticipate two to three
years of operation without degradation in normal use. The tubes have
also been hand selected to achieve the minimum residu al noise in your
preamplifier. Therefore, we highly recommend that when the time
comes to replace the vacuum tubes, you purchase replacement tube
sets from conrad-johnson design.
Refer to the diagram on the next page for tube locations.
EVOLUTION 20 OWNER’S MANUAL
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