Lifespan of a quality solid state amplifier?

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Minor I would have to disagree with "it is only too late if it fails" when it comes to audio. The statement may be true with power supplies for some equipment, but since they typically affect the sound of an amp long before they fail they have to be replaced sooner if your goal is optimal sound.

I do agree you should only replace caps in really old amps when necessary, but if we take 30 or more years to be really old then IMHO it is necessary in all of them. Bulging or oozing or not those caps have deteriorated. They need to go.

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Thanks Atmasphere; you are entirely correct and I also replace caps if I notice the bulging plug. I forgot to mention it. Again, for those interested, this is part of routine inspection and service. For expensive high-end electronics, this is something that I definitely recommend.

enjoy all

I am in the same boat with Ralph as the mallory caps I see in 5v200amp switching power supplies also have the greyish white vent plug positioned half way between the plus and negative terminals on the cap;they will start to push up and show signs of leakage.Once the electrolytic gets on a pcb it damages the board and shorts seem to start occuring thus rendering the mainboard unrepairable.

I have an over thirty year old APT Labs amplifier that is still running a pair of old 1979 B&W 801's! Yes, it's a 100-watt amp into 8-ohms and runs near clipping all the time. It sounds fine.

Electrolytics are no better than +/- 20% tolerance so that wear is less sensitive than you might think to sound. Caps in the more sensitive audio path that are non electrolytic give you a better circuit life if anything. There is no "proof" that exotic caps sound better over just last longer (at a price). Large electrolytics in the power path are cheap to service, too.

Most smaller electrolytic caps, if mounted right to lower lead inductance, often have the lead end (where they leak) SHORT and right to the PC board. You can't see the caps leaking when they do go till it's too late. Large power stage electrolytics are faced "up" with the terminals using screws. Inductance isn't as important in the DC path. You can watch these for signs of deterioration.

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Rower

What you say is just plain wrong.

Unless it is bulging or leaking fluid it is impossible to visually inspect a cap and determine if it has deteriorated. The capacitance drops and ESR goes up and they leak current and you have no way of knowing if or how much just by looking at it. You can delude yourself if you wish but all electrolytics slowly deteriorate in ways you cannot see.

All electrolytics have a limited lifetime. Take a minute to google the topic and you will get hundreds if not thousands of hits discussing this phenomenon.

It is impossible that your 30 year old caps function as well as new ones. To deny this is to deny that which has been studied extensively and is well documented. Your amp may sound "fine" whatever that means but that does not mean it wouldn't sound better with fresh caps.

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