Automatic Bias Control sliding bias

[litefoot22]

Automatic Bias Control or sliding bias. There is a rather interesting article on the Brooks Amplifier in one of the audio magazines this month. I was quite intrigued in the idea. The idea is rather simple, a Push Pull is biased for class A. As the signal increases above 5 watts output, The bias Ckt increases the bias and slides the tubes into class AB1. Higher output the tubes slide into class AB2. The Brooks amp is from 1947 and a bit dated has anyone experimented with the Ckt. Any input would be welcome. George

 

[litefoot22]

Here is a link to the brooks...George
http://www.tubecad.com/2007/12/15/High-Quality Audio Amplifier With Automatic Bias Control.pdf