VAC Phi 70 User Manual
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Tips: Output Tubes
Your VAC Amplifier uses the 300B or 300A filamentary triode. It is strongly recommended that
replacement tubes be purchased only from VAC. If, however, you want to customize the sound
to your tastes, be aware that as with interconnects and speaker cables, each tube manufacturer's
300B tends to have a distinct sound, as well as its own reliability profile.
Tips: Low Level Tubes
The Voltage Amplifier/Phase Splitter and driver tubes in the Phi Seventy is the 6SN7 medium mu
octal twin triode. Your amplifier is fitted with the current production VAC Tested 6SN7 from China,
which we find superior to the NOS types we have tried. There are dozens of versions of this tube
available in new old stock (NOS) from a variety of sources. It would be impossible to characterize
them all.
Other equivalent type numbers are 5692, 13D2, B65, ECC32, QA2408, QB65, and CV1988.
Tubes V1 and V2 should be transconductance matched, and tubes V3 and V4 should be
transconductance matched; this minimizes distortion.
We strongly recommend obtaining tubes as sets from VAC.