The life span of a capacitor depends on the voltage it sees and the temperature of its environment. For example, I had to recap my 15 yea-old at the time Audio Research 100.2 because a couple of the power supply caps were bulging. The reason was obvious: the capacitors were rated at 50 volts and the voltage rails are 50 volts. So the cap's lifespan was shortened because it was operating at the voltage margins. I replaced them with 63 volt caps so that their lifespan will increase by 50% in that application.
On the other hand, my 1970's 30-watt Marantz receiver's power supply caps test as practically new. That's because their voltage rating is much higher than the rail voltage and there is practically no heat generated inside. Still sounds great.
On the other hand, my 1970's 30-watt Marantz receiver's power supply caps test as practically new. That's because their voltage rating is much higher than the rail voltage and there is practically no heat generated inside. Still sounds great.