Nothing to worry about. I'm not sure about the newer VH4s but mine has that switch too. It is there to adjust the range of the bias pot for the particular tube. If you put EL34 in, set it to EL34, if you put 6L6 in set it to 6L6.
Nothing to worry about. I'm not sure about the newer VH4s but mine has that switch too. It is there to adjust the range of the bias pot for the particular tube. If you put EL34 in, set it to EL34, if you put 6L6 in set it to 6L6.