[Amps] amp.tube bias

[carlseye@tampabay.rr.com (carl seyersdahl)]

The other day I questioned a person about the bias on an amp he sold!!  this
was agla1000 with EL509's.. he stated that the the bias was 12 v. at idle
and 6.9 under full power! this certainly doesn't seem right to me , or am I
missing something??
 I was taught that the bias for a class a- ab1-ab2 -b amp should stay the
same at all times... Have times changed or the technology changed? Or have I
forgotten something after so many years???
   carl / kz5ca