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When is used used up?

Is there a rule of thumb that says the savings of buying used equpment is offset by the age of said equipment? Surely, aging negatively effects circuits -- welds weaken, capacitors lose capacity, transistors tire, wiring oxidizes, etc. My first amp in 2000 was a Mcintosh 250 in A- cosmetic condition. When I replaced it five years later with an HK PA2400 (used), my system took on new life (more than the increase in wattage).
Seems like when a component is old, it's old, be it sacred cow or not.
garn509

Showing 2 responses by normansizemore

normansizemore
601 posts
 
I have owned many old mac amps, and when I acquire them, I send them to Mac for general servicing. I have NEVER had them do anymore than replace a burned out lamp. Ever! And I am talking about amps and preamps that were 15 to 30plus years old. Each one met spec. The same is true when I bought my harman kardon Citation 17 preamp and 16A amplifier. I sent them to hk on Long Island and they sent them back with a data sheet. They far exceeded factory specifications. It erks me a little when someone says 'oh I replaced the caps in this or that and now the unit sounds awesome' (caps are so easy to change and this seems to be the rage today) Capacitors do NOT DEGRADE over time, they FAIL. Which means if your amp is playing, your caps are fine.

So, I think that if a unit was manufactured using quality parts, you should be ok, at least that has been my experience.
Norman
normansizemore
601 posts
 
"Power supply capacitor is in series with a speaker (circuit closes thru power supply) and any increase in ESR will show as worse bass control (lower DF) and loss of dynamics."

I would love to read the white paper on this.. if you have one please let me know. Yes, caps can dry out and when they do the short or fail. Until the point of failure, it is my understanding that they are performing/suppling necessary and proper capacitance and therefore should have no adverse effect on the circuit.

Norman
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