Tung-Sol Tube Upgrade Kit For Peavey JSX Amps EL34B 12AX7 This set includes (4) Matched Tung-Sol EL34B power tubes (3) Tung-Sol 12AX7 preamp tubes (1) "Gain Balanced" Tung-Sol 12AX7 preamp tube (phase inverter) marked with yellow "Balanced Triodes" Sticker