Is there an average life span for a preamp?


I have a 6 year old Adcom GFP-750 preamp that has been used for about 12,000 hours already. Is there a certain point in hours or years when I can expect something to fail? This particular preamp has a passive option which I like and use currently. When used pasively I would thing that it should last forever.Please let me know what experiences you have had. Thanks.

Joe
jjarocki

Showing 5 responses by kijanki

Joe - 12000hrs is nothing. The only perishable things inside (other than mechanical switches) are electrolytic caps. Their life is in order of 50years in room temperature. Every 10deg C temp. increase cuts their life by 2 (they dry-out). Since preamps tend to run cold I wouldn't worry for at least next 20 years.
AFAIK every preamp is class A. Saving power (class AB) is unimportant in preamps.
Atmasphere, My calculation based on Nichicon data shows that at 35degC (95degF) standard caps should have 80% of capacitance after 17.8 years. Each 10degC cuts life in half, so I would estimate not more than 10 years for caps in hotter amps unless 105degC or long life caps are used. When ESR of the cap increases to cause substantial heating from ripple current they get even higher ESR (since ESR increases with temperature) and thermal runaway causing to blow fuse or scored top. It happens when capacitor is very old and starts running hot. It should be easy to detect such caps especially since there should be other symptoms like less dynamic sound, poorly defined bass, 120Hz noise etc.

I can understand that many audiophiles have "gardener's syndrome" (constant need to trim and re-pot) but if it sounds good to you - don't touch it.
"universally accepted amongst those who do such work that the filter caps in the power supply should be among the first things to be changed during a restoration"

I agree. I would also like to have caps changed during restoration of old amp but would not do that otherwise (without a cause).

I assume that amps with minimal feedback are less forgiving but issue of increase output impedance (ESR of capacitor) is complicated one. My class D amp with DF=4000 at low frequencies sounds great with my speakers. I'm pretty sure that increased output impedance might make it sound better with other speakers. In such case audiophile satisfied with great sounding older amp replaces caps, following advise of an "expert", for the worse sound. Do I make sens?
Ralph, that might be because of the inductor in series with the woofer that has resistance in order of 0.08ohm at best, but some people still complain about overdamping and the lack of bass.