Rick,
Your assumption is not good since tubes are matched to each other. The negative grid offset voltage may vary in EL34 from -35V to -55V the more negative is grid voltage the less current flows through the testing socket.
The grid supply is adjustable in all VTL-s although I'm not sure if the pot is accsessible from outside just like the bias ones. In worst case you should bring it to tech and he/she will set the bias supply correctly for your new tubes. If you're near NY area than you can bring it to me and I'll take care of it in few minutes of waiting.
Your assumption is not good since tubes are matched to each other. The negative grid offset voltage may vary in EL34 from -35V to -55V the more negative is grid voltage the less current flows through the testing socket.
The grid supply is adjustable in all VTL-s although I'm not sure if the pot is accsessible from outside just like the bias ones. In worst case you should bring it to tech and he/she will set the bias supply correctly for your new tubes. If you're near NY area than you can bring it to me and I'll take care of it in few minutes of waiting.