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Kevin: For SET design, how much ripple is too much ripple

Posted by AnandR (A) on July 16, 2004 at 04:46:01

I have a 3 stage SET amp I am designing a power supply for, no active loaded current sources or chokes just resistor loaded for each stage. So no fancy PSRR rejection. The input and driver stages do have their own RC hum filtering stages however employing 50uf caps.

The power supply employs the Hybrid Graetz principle (HV tap: 260-0-260) using two Schottkey 1200V rectifiers and two 6AX4GTB damper diodes in a full wave bridge. The first cap is 2uf then the Lundahl 1638/4H choke then another 50uf cap then another Lundahl 1638/4H choke and then a 100uf cap. Final B+ is 440V at 270mA. Ripple is 22mV as measured by Duncan amps.

Although I would love to raise the value of the first filter cap, the B+ is raised much too high. The other option is to raise the value of the last filter cap to something like 200uf which drops the ripple to about 10mV.

But I get to question for an SET amplifier for loudspeakers, is 22mV too much ripple?

Thanks,
Anand.

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