Decware Zen Triode Preamp Owner's Manual page 9

O W N E R S M A N U A L
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TUBES
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The ZTPRE uses 3 dual triodes per channel to create a true balanced preamp. So if you look at this preamp and
think of it as a V6 race engine as it's looks would suggest, it is actually a V12 using 12 triode stages to achieve audio
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bliss.
ZTPRE is designed for the higher heater current requirements it's factory tube compliment of 6N1P-EB tubes. These
are the smoothest and the warmest tubes available making use with digital sources particularly synergistic.
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Replacement tubes are always available from DECWARE.
One of the unique features of the ZTPRE are the heater circuits. Each channel has it's own AC heater supply which
was found to sound better than DC due to the inevitably higher current potential for the dollar, and the ZTPRE took it
a step further with a high voltage 18.9 volt supply rather than 6.3 volts. This requires all the heaters of all three tubes
on each channel to be wired in series. After extensive testing between AC, DC, it was found AC sounded better.
After additional testing between 6.3volts where each tube is wired in parallel vs. 18.9 volts where all three tubes are
wired in series saw another market increase in sound quality. It creates an interconnectedness between all the
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tubes of the various channel and gives it the more transparent single ended sound the ZTPRE is famous for.
This means that if the heater burns out in one tube, all three will go dead just like old fashioned Christmas tree lights!
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This is very rare of course but helps to know what can happen in rare cases.
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The main rule with this type of circuit is that all three tubes should match as far as heater draw. See next page.
Decware High Fidelity Engineering Co., East Peoria IL, USA www.decware.com