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"In the case of the Blues DeVille, it looks like someone finally gave it some thought and put the +5/-10 tolerance on the supply voltages (105% of 471 is 495). That still seems a little wide given that the line voltage is also specified."
Well, given manufacturing tolerances (e.g. most current Fenders read high compared to the schem when wired for UK operation), fluctuation in wall AC over the course of a day, brand of tube, state of bias...that +5% seems reasonable, I have read in excess of 500vdc on a De Ville, but the modern Fender PTs do not seem quite as consistent as those from the 50's & 60's (I have read from 465v to 525vdc on the RI Bassman, all with SS rectifiers). However, even back then voltages were prone to being periodically bumped up without a new part no. necessarily being issued...but when checking amps from the same period (pot/transformer dated) <5% is fairly typical.
Well, given manufacturing tolerances (e.g. most current Fenders read high compared to the schem when wired for UK operation), fluctuation in wall AC over the course of a day, brand of tube, state of bias...that +5% seems reasonable, I have read in excess of 500vdc on a De Ville, but the modern Fender PTs do not seem quite as consistent as those from the 50's & 60's (I have read from 465v to 525vdc on the RI Bassman, all with SS rectifiers). However, even back then voltages were prone to being periodically bumped up without a new part no. necessarily being issued...but when checking amps from the same period (pot/transformer dated) <5% is fairly typical.
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