Tube Preamp: 12AU7 Tungsram. (= ECC82) NOS=New Old Stock from 1970s!!
Perfect for your old Vox!
12AX7 - ECC83, 7025, ECC803, E83CC, 6681 : GAIN 100,
5751: GAIN 70,
12AT7 - ECC81, 6201, 6679 : GAIN 60,
12AY7 - 6072 : GAIN 45 12AV7 - 5965 : GAIN 41
12AU7 - ECC82, 5963, 5814, 6189 : GAIN 19
Preamp Tube Gain Factor Choosing pre-amp tubes by gain factor One simple tweak that is favored by guitar amp users is to plug in a pre-amp tube with a slightly different gain factor.
Replace the V3 12AT7 Reverb Driver tube with a lower gain 12AU7 to give you more usable room on the Reverb Control. The Reverb pot can be a little touchy with a usable range from 0 to 3 or 4. A 12AU7 wont push the reverb circuit as hard so the usable range can extend up to 5 or 6 on the dial and make dialing in just the right amount of reverb easier. The lower gain 12AU7 can also reduce reverb circuit noise..