Easy biasing Tube amps

The VAC amps I've owned were very easy to bias, no tools needed. No meter, no screwdriver. Of course I also owned BAT tube amps which were auto-bias....even easier.

PrimaLuna are autobiasing. You don't have to do anything at all except plug the tubes in. This also allows you to use a variety of tube types (EL34, KT88, etc.) in the same amp.

Cary CAD 120's you adjust the bias on each channel with a small screwdriver. There are meters on the front.

Atma-Sphere is part auto-bias and part manual. IOW the bias is automatic but you still use the onboard meter to set the DC Offset (there is a single DC Offset control because the output of the Atma-Sphere amps is direct-coupled). Drift is low, so the control need only be adjusted once every few months or so. Unlike a bias adjustment the DC Offset is not a critical adjustment.

The new Carver VTA amplifiers allow one to bias the entire bank of power tubes at the same time. Tubes do not need to be matched and once set there is rarely a need to recheck periodically.

I was reading that VAC is taking auto biasing in a direction worth looking into.

03-22-13: Polk432
Cary CAD 120's you adjust the bias on each channel with a small screwdriver. There are meters on the front.

Yes, but the Cary has the meters in the front and the bias adjustment screw in the rear. Who thought that up? That's what has kept me from buying a Cary amp, I have a Cary preamp. The rear on my amp is not easily accessible.
VAC has the meters AND the adjustment knob (no screwdriver necessary), right up front where they belong. So simple an idiot like me can do it!

Rogue Atlas is easy. Flip a switch, turn a screw, read a meter on the top panel. Simple.