What the heck is bias anyway?

My injectors are class D but I only run them in class A. I generally bias with IAC adjustments but sometimes fuel pressure.

Mitch4t, this depends on the amp. Some amplifiers have very stable bias settings and can be checked maybe once every 6 months. Others seem to need constant observation. So I would go with the manufacturer's recommendations.

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Thanks for the reply Atmasphere. I really would like to try tube amps, but I'm not mechanically inclined at all. I'm a plug and play kind of guy, which is why I have solid state amps. I'd consider tube amps as long as they don't require much fiddling around with. I think I read somewhere on Audiogon about self-biasing amps. If that technology exists, why don't all tube mfgs use it. Is self-biasing expensive to implement? Is it as accurate as a manually biased amp?
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Mitch4t, automatic bias as a feature varies from amp to amp. With some systems it is quite simple and others rather complex. The accuracy varies too. For the most part what autobias means is that the most 'fiddling around' will have to do with initially setting up the amp, and after that dealing with the occasional bad tube. None of that is particularly difficult. You can run into issues with any audio product that might be equally as easy or perplexing.