Transistorized audio power amplifier

Claim 1

A POWER AMPLIFIER COMPRISING FOUR TRANSISTORS HAVING THEIR COLLECTORS AND EMITTERS CONNECTED AS A BRIDGE CIRCUIT, SAID BRIDGE HAVING TWO BRANCHES WITH COMMON TERMINALS AND TWO LEGS WITH A MIDPOINT BETWEEN THE LEGS IN EACH BRANCH WITH ONE TRANSISTOR IN EACH LEG, IMPEDANCES CONNECTING THE MIDPOINT OF EACH BRANCH OF THE BRIDGE WITH THE BASE OF ONE TRANSISTOR IN THE OPPOSITE BRANCH, SAID BRIDGE ADAPTED TO HAVE A POWER SOURCE CONNECTED ACROSS THE BRANCH TERMINALS, LOAD CONNECTIONS AT THE MIDPOINTS OF SAID BRANCHES, A PAIR OF SIGNAL INPUT LEADS, MEANS CONNECTING ONE LEAD WITH THE BASE OF THE OTHER TRANSISTOR IN ONE OF SAID BRANCHES FOR CHANGING THE VOLTAGE AT THE MIDPOINT OF SAID ONE BRANCH RESPONSIVE TO A SIGNAL, A VOLTAGE DIVIDER CONNECTING SAID MIDPOINTS, MEANS CONNECTING THE CENTRAL PART OF SAID DIVIDER WITH THE BASE OF THE OTHER TRANSISTOR IN THE OTHER BRANCH FOR VARYING THE CURRENT IN SAID OTHER TRANSISTOR IN SAID OTHER BRANCH TO CHANGE THE VOLTAGE AT THE MIDPOINT OF SAID OTHER BRANCH AN AMOUNT EQUAL TO AND IN A DIRECTION OPPOSITE TO THE SIGNAL PRODUCED VOLTAGE CHANGE AT THE MIDPOINT OF SAID ONE BRANCH, A SECOND VOLTAGE DIVIDER CONNECTING SAID MIDPOINTS AND MEANS CONNECTING THE OTHER SIGNAL LEAD WITH SAID SECOND VOLTAGE DIVIDER TO PROVIDE A NEGATIVE FEED BACK.