tube amplifier auto bias- accurate?

While autobias is certainly more convenient, and I do not know if one is better than the other sonically, I have heard manufacturers claim that adjustable bias normally yields longer tube life.

In fact, Rogue's new amplifiers have made the switch from autobias to user adjusted bias. In addition to the tube life, I have read they feel it also has produced better sonics.

If sonics were equal, obviously autobias is preferable. If there is some audible improvement by not implementing the circuit, it would be good to go in that direction, and make bias adjustment an easy task, with easy accessibility to the adjustment (like AtmaSphere, Cary, CJ, Jolida, Quicksilver, but NOT like Jadis).

I wonder if Macs were the first ones to implement autobias successful in their vintage gears like the MC240s.

Ed_sawyer...Actually, you can use a scope to measure voltage if you are too lazy to go to the cabinet and dig out a voltmeter. Or, if you want to impress an audiophile.

I also know how to add on a slide rule (remember those).
And count to 35 on my fingers. (Hint...use two-place base 6).

Eldartford, one cannot add on a slide rule, only multiple and divide and other operations, but no adding (nor subtracting, obviously). The scales are logarithmic to permit multiplication by adding powers. I still have my sliderule in my desk, for nostalgia!

Bob P.

"I wonder if Macs were the first ones to implement autobias successful in their vintage gears like the MC240s."

Doubtful. bias as a concept is as old as tubes, e.g. early part of the 1900s, 1910-1920 is when most basic concepts and methodologies were developed. Not much has changed since then. Things rediscovered, e.g. Parafeed, etc.

-Ed