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Acoustic 220 power amp

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  • Acoustic 220 power amp

    I finally have this PA working again but have a question about the AGC circuit. Are Q1/2 some sort of detector used in the AGC loop? How does the AGC work in this design?

    This amplifier just about puts out 18Vrms (@2.7 ohms) before the positive part of the input signal starts to degrade. I'm also only getting 60 V out of the secondary at 120 V on the mains. I'm going to assume this was typical ACC production control in 1977.


    220PA.pdf
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