HERETIC OWNER’S MANUAL
PAGE 13 OF 16
TUBES
TUBE LAYOUT
V1 – Common
V2 – Channel 1 (Clean)
V3 – Channel 2 (Gain 1)
V4 – Channel 2 (Gain 2)
V5 – Loop
V6 – Phase Inverter
CHANGING/REPLACING TUBES
Preamp tubes have a much longer life than power tubes. You are not likely to have to
replace them unless one or more tubes fail. Preamp tubes can have a life span of at least
two to three years and usually much longer. If it becomes time (say it’s been a few years or
you regularly change your power tubes and feel like the amp has become lifeless), contact
DA for a replacement set. If you want to buy tubes on your own, please consult DA to ensure
you do not buy an inappropriate tube. Generally, however, any good 12AX7, ECC83 or
replacement tube will be OK, although they can change your amp’s tone.
If you play regularly, power tubes should be changed every 6 months to a year. If you don’t
play frequently, they can last longer.
NOTE: While power tubes can simply and suddenly
fail, they generally degrade over time. So while your tubes may be working, they will
not sound the same as they get older.
People often go years with the same power tubes
and never replace them claiming, “Well, they still work fine.” You can be assured that the
amp, however, does not sound the same as it does with new, functioning tubes. DON’T
WAIT UNTIL YOU HEAR A DIFFERENCE. FOLLOW A REGIMENTED TUBE CHANGING
SCHEDULE TO AVOID HEARING A DIFFERENCE.
When it is time to change power tubes, bias should always be checked. It is easiest to have
a qualified tech retube and rebias your amp. If you buy replacement tubes from DA, you may
not have to adjust bias as your tubes will be of the same or similar rating and matched
correctly. It is still good, however, to verify bias. If you feel competent to check or adjust
bias, call DA for instruction. But generally, bias should average between 33 and 39 milliamps
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