[Amps] Expert 1k amp

[Steve Thompson]

Yesterday I did some minor repairs to a friend's amp - resoldering 
joints on the current sensing resistor. Looking at the circuits 
later I noticed that the main supply voltage is regulated by 
having SCRs in place of diodes rectifying the transformer 
secondary and the main smoothing capacitor is 47000uF.

My friend tells me the amp runs over 40A at full tilt, which means 
something like 8.5V ripple on the supply (7V at 60Hz). That 
strikes me as quite high and I'd expect to see some difference in 
amplifier gain/output if I was running such an amp off a regulated 
supply and altered the voltage that much. Has anyone measured one? 
Is any 100/120Hz audible on a carrier?

Steve