And here they are. 100uF 700VDC each. So a little shy of the stock capacitance. Mounted but not yet connected. I need to cut and router some simple risers to raise the (still unfinished!) base by about 2 inches.
One of the new caps is likely only visiting. I am going to experiment with replacing each of the 120Rs with chokes. A 4H 65 DCR 225mA rated in place of the first R, and a 6H 150R 200mA rated in place of the second R. But PSUD shows that the combination of the chokes and the 2 new caps (or even the stock 110uF effective value caps) results in initial B+ overshoot and then dip -- and from what I've read that looks like a recipe for ringing. So I played around with different configs and found that a 200uF cap in last position completely eliminates it. In PSUD ripple is reduced to about 0.02mA pk-pk! For reference, PSUD shows about 20mV pk-pk ripple with the stock filter config, and approx. 0.8mV pk-pk with the last RC replaced by the 6H choke and a 100uF cap. We'll see if any of this actually works out in reality. I'll scope the amp this weekend to get some baseline measurements before making any changes.
[edited to add PSUD results for the stock filter config and for when the last RC stage is replaced by an LC]
cheers, Derek