tube amplifier auto bias- accurate?

Most auto control processes are as good or better than you can do manually. This would obviously be a requirement on the designer.

In airplanes, even little ones, the autopilot flies the plane more accurately than a pilot. This is hard for macho pilots (like me) to accept, but fuel consumption on a long trip proves the point.

I agree that auto bias is a good thing, I had very positive experience with the amps I owned.

As for tube testers, the B&K 707 or 747 are decent and can usually be had cheap at EBAY. Best of all they are transistor and need little or no calibration and won't drive you crazy with too many knobs to turn to get a reading.

Later, if you want a high end tester, the Hickok 752A is one of the best ever made but much more complicated.

A real easy tube tester for a beginner is the B&K 606. It comes in a small case like those portable 45rpm record players of old. Less options than the ones Albert is recommending, but it's smaller and can test a wide variety of tubes. I got mine in great shape on Ebay for I think around 50-60 bucks.

There are many ways a tube amp can keep self-bias on the tubes. It's neither better nor worse than fixed (Manually adjustable) bias. Some of the tradeoffs are that usually one method (fixed bias) allows a little more power output. For fixed bias an amp usually needs a separate bias supply, which adds to cost/size/complexity. The methods of self-bias vary, the most common is cathode-bias where a resistor biases the tube. Other units (BAT Vk60 come to mind) use a more sophisticated method of bias where its more of an auto-regulated active bias voltage than a simple cathode-bias self-regulating system.

both methods sound good, and adjusting bias manually is not a big hassle. Sometimes it's nice to have fixed bias in that it allows changing the operation point of the tube, which is not generally possible with a self- or auto-biasing amp.

-Ed

I am sorry to disagree with everyone so far. I have owned numerous tube amps from low cost to very expensive. Some auto biasing and others not. There is NO substitute for having your amp biased by a professional with a scope. None.
Ask a tech and see if they don't concur.