I am a recent convert to tubes (about 3 years) and have purchased a tube line stage and power amp, and have done a great deal of reading on the subject but I only recently came across this tube when reading about the Wright Sounds WPP 100 phono stage. this unit uses 4 of these tubes along with 2 12AU7's.
In all the searches I have done for tube gear and in all the reading I have done I did not come across a unit using the 6ER5 tube except for the Wright Sounds unit.
What is the benefit or shortcoming of this tube that it is not widely used at all (my perception) compared to the more common 6DJ8, 6SN7, 12AX7, etc, etc in preamps? It seems so odd that every other manufacturer/designer uses the more common tubes but the Wright Sound WPP100 uses this obscure one? Thank you