Abstract: A feed forward amplifier circuit which includes a main amplifier, an error correction circuit producing a message error signal, an error amplifier for producing an amplified message error signal that is then subtracted from the amplified and distorted message signal output of the main amplifier prior to a final output circuit, a negative feedback circuit coupled to the final output circuit responsive to a test signal for compensating and minimizing drift in the operation of the error amplifier, and circuitry associated with the negative feedback circuit for detuning performance of the error correction circuit at the test frequency so as to improve the overall circuit performance across a desired operating frequency band while diminishing its performance at the test signal frequency.