[codefox1]

Thanks, Ron. I think I was just wondering why the "B-" developed by the audio stage was never tapped in these early designs to provide tiny current supplies for the bias circuits.

Of course I could take a small capacitor off the secondary of the the transformer, and make a bias supply much the same as you can do with any amplifier to produce a "C" supply, then divide it into the values I need, but I am still in wonderment why this was not done before. The answer may well be the cost of a couple of electrolytics at that time. I understand that bias batteries would last about as long as they would whether on the shelf or in use; about the same as the ones that rust and corrode our ancient VTVM's without warning.

Thanks