If you have a condition where you have too much gain with the VTPH-2A you can use 12AT7s in all 5 positions which will lower the gain by an additional 5dB. Always, make sure you are using long plate 12AT7s such as the ElectroHarmonix 12AT7EH in positions V2 and V4. These have more grid to plate capacitance and will keep the passive RIAA network from sounding thin (no feedback is used in the VTPH-2A). For more gain use short plate 12AX7s in positions V2 and V4 in order to keep the RIAA response accurate. If you originally purchased a 4 x 12AX7 version
(we did not sell many of these) the rules are a little different for V2 and V4 - those can be long plate 12AX7s. Check the back of the VTPH-2A for the tube set markings. When tube rolling you can use any 12AX7 you want in positions V1 and V3 on either version of the VTPH-2A. 12AU7s will not work in this design. Tube locations are marked on the circuit board and in the owner's manual. - Keith Herron
