Class AB amp clipping at 55v under no load, help

Hey everyone,


I’ve built a 1000W RMS amplifier designed to drive a 2Ω load. I'm supplying it with ±80V rails. However, when I check the output voltage (without any load connected), the signal starts clipping at only 55V peak.


I was expecting a higher swing, given the rail voltage. Could this be due to a weak driver ? Would adding a predriver help improve the voltage swing?


Any insights or suggestions would be appreciated

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R5 suggests a constant current of 6 m.a. for the Vas do you think that is enough to drive the following buffer stages through to the output. What is the voltage across R16 and apply Ohms law to deduce the current and is that sufficient also.