Thermistor before first filter cap?

[Cliff Schecht]

My Deluxe clone has an "issue" during the initial power on. I have a 330-0-330 transformer feeding a 5Y3GT and this goes directly into a dual 10uF, 450V can cap. The can cap was a NOS unit from the mid 1950's that I had laying in my junk pile. I tested it for leakage, reformed it and called it a day. The thing that worries me is the initial voltage surge of the charging cap, it momentarily rises to over 500V before dropping down to its nominal 290V.

What I'd like to do is put an NTC thermistor in the B+ line to drop down this initial surge. The usual place to put this is in the primary lead of the PT but since I already have a standby switch, I don't need to muck with the heater warmup time as well and this would not bring down that initial surge enough (at least I don't think so). I don't like the idea of a B+ dropping resistor before that first filter cap either, it would have to be somewhat large (at least 7W) and would drop the B+ too low. So, does anybody have any advice on what to do here?

[Jana]

Maybe remove the standby switch and just let the B+ rise slowly as the rectifier heats up.

[Cliff Schecht]

That's how I originally had the amp. I did recently add limiting resistors before the tube rectifier (47 Ohms per leg) but the voltage still rises slightly over where I want it, even when bypassing the standby switch (goes to 483V max instead of over 500V). I could place a small resistor in series with the B+ to drop this but I'd like to find a more efficient fix..