So, uh.
How do you make sure the DC voltage is divided evenly across a series string of electrolytic capacitors?
Not so much a matter of opinion but of physics. Two factors affect this. The capacitance of each unit in the string dictates the 'share' of the total voltage each one will get. The actual measured capacitance of large electrolytics is NOT tightly controlled, and often varies by 20 percent or more. Feel free to consult your local physics textbook for the rule that defines how a DC voltage is divided across unequal capacitance values in a series circuit.
The other factor is the internal leakage resistance. If they are all equal, no problem. If they are not, Ohm's law will apply. Even if you go to the trouble measuring that internal-resistance behavior of each individual capacitor, there's no guarantee that this parameter won't change over the life of the part. Sadly, the capacitor with the highest leakage resistance gets the largest share of the divided voltage. The leakiest capacitor in the string gets the least voltage share.
If the DC voltage is not divided evenly, one of them will end up with more than the rated DC voltage across it.
What happens next is also much more physics than it is opinion.
Oh, and speaking of physics. Three 220k resistors add up to 660,000 ohms. Together they will draw about 1.5 mA from a 1000-Volt DC power supply. Adds up to 1.5 Watts of "stolen" power from your high voltage. Your amplifier has to be pretty small for a Watt and a half to hold it back in any real way.
73
