Is rectifier tube arcing a problem?

decay - Are you offended? Your multiple comments here were of no value. I was not commenting on you, as I do see that you do make valid contributions occasionally. My comments were meant to encourage imhififan and atmasphere to contribute more often. I have a lot of respect for both of them.

My 2cents - Seems clear that this an inrush current problem, which reducing the capacitor values would help to reduce. It has been my experience that reducing power supply capacitance does usually negatively affect low frequency capabilities. If I were going to reduce the cap values, I would not reduce more than necessary. Say from 220uf to 100 instead of going all the way down to 47uf.  The diode idea was excellent. How about doing both, diodes and just the 220uf caps to start with?

A few years back I built an ANK Kit-1 300b stereo power amp.

The rectifier tube arked upon power up. I contacted ANK’s builder at the time and he suggest trying a new EH 5u4gb. Told me to buy two or three cause one might ark even new, so throw it away (and any other rectifier tube that arks at startup).

I bought three and only one arked at startup. I marked it and some others but never threw them away lol.

It’s been working fine ever since although I don’t use it constantly.

I did notice shortly after that ANK started including the EH 5u4gb with their kits. But that was then.

Say from 220uf to 100 instead of going all the way down to 47uf.

@fiesta75 

You work out the timing constants. The amp likely does not have a timing constant in the audio circuit that is less than 5Hz since the output transformer won't go down anywhere near that. So it will not be able to modulate the power supply if the power supply has timing constants of below 5Hz. 220uF is way overkill; I don't know of a tube rectifier that will survive that.

Not only that and more importantly, the load on the power supply is constant owing to the circuit is class A- it draws the same power at idle as it does at full power. This makes the power supply requirements a lot simpler. That is why 47uf will be fine. I have an amp that makes the same power and it has only 30uF in this position. The power supply voltage dominates the equation when you're talking about energy storage to do work (like driving a loudspeaker). The formula is:

Work = 1/2 (C x Vsquared)

That is why tube amps don't need nearly the power supply capacitance as solid state amps do.

atmasphere - Thanks for taking the time to educate, me anyway. I have always appreciated and respect the knowledge you and imhififan have brought to the AG forum.👍

That’s my amp on the Steve Hoffman forum. I haven’t had any issues with arcing but as you can see in my thread, I used a soft start before the mains transformer, and also have a lot less capacitance hanging on the output since I used a Maida regulator for the driver tube. 
 

Hope you come up with a good solution.