Audiophilepure

Another often-overlooked type of distortion is phase modulation, which occurs when the circuit’s speed varies with the audio signal’s amplitude. Like crossover distortion, phase modulation produces a distortion profile that varies across the different frequency components of the music signal. For instance, the (usually large) low-frequency components of a bass instrument can cause time smearing in the higher-frequency components of instruments and voices. In the power stage and other signal stages of the PA1, dedicated design techniques, including feedforward corrections, keep this type of distortion extremely low.

With this highly optimized and fast amplifier circuitry, an appropriate amount of global feedback is applied. Grimm developed a second-order feedback loop for the PA1, which further reduces the last remnants of distortion. The very careful and unique design of this feedback circuitry – again preventing phase modulation and thermal errors in this part – further strengthens the fidelity of the amplifier.