Preamp Tube Question

kitjv -- Sat, 02/05/2011 - 21:33

I purchased a new Audio Research SP16 tube preamp in January 2008. The vacuum tubes have never been replaced & the unit have been used on a daily basis. I know that sonic quality will deteriorate with tube age. But rather than wait until the sonic quality becomes audibly degraded, would it be prudent to replace the tubes now (i.e. after 3 years)? Would there by any advantage of replacing the tubes with an aftermarket variety or would it be preferable to order OEM tubes from Audio Research? Thank you for your help.

kitjv -- Tue, 02/08/2011 - 11:41

After considerable input from other sources, this question has been answered adequately for me.

Ded Frag -- Wed, 02/09/2011 - 18:59

 That's good kitjv but could you let us in on what you learnt? I'm running a valve pre-amp too and would be interested to hear what was said.

paulwelch250 -- Mon, 08/29/2011 - 19:31

The tubes in most preamps are not stressed very much and should last 10 years provided one is turning off the preamp each day and having them on say 2 to 8 hours per day.  Most tube preamps sound great in only 5 minutes and do not be turned on for hours or left on always like many solid state products.
While the heater in the tubes do deteriorate over time the sound quality actually improves slightly over time.
Every case if probably different and you have to keep the bias adjusted, (once a month good idea for first 6 months and then once a year after that) but often the preamps tubes sound their very best in years 2 to very nearly the end of their life.  As to autobias amps, they will take care of themselves as far as the bias (not sure if they will ast any longer or not vs. well managed non auto bias preamps).
Power tubes in power amps, EL35s, 6500... will tend to last 5 years if used 2 to 8 hours per day and same thing actually sound better over time
until close to end of life.

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