? Tube Replacement Question ?

I recently replaced the tubes in my sp16 after about two years of fairly heavy use.

In my case, the issues I noticed with age was noticeable background noise that was not there prior.

I replaced all 6 tubes with Groove Tube Gold 12AX7s from Guitar Center for $20 each.

I decided to try to buy from the GC down the road first before going to ARC for their "certified" tubes at higher cost.

The olny difference I notice in sound is a tad more background noise in the phono section than prior perhaps, but nothing significant. The sp16 is very quiet now as it was with the new tubes that came in the unit from ARC when I bought it.

I figured if these did not work out, I would buy then from ARC and keep these as spares, but things have in fact worked out well.

One thing I found out of value is that rearranging the tubes internally can have effects on the amount of background noise produced. The trick is to get the best/strongest tubes into the prime slots I believe either by trial and error as I did or perhaps using a tube tester. I was able to prolong the useful life of my original tubes by almost a year doing this.

I always buy a new tube set when I get a new piece of equipment. Worst case, (outside of spending extra money) is I then have a spare set which is very useful, especially in diagnosing quickly if I have a tube problem or something else has gone wrong. Normally I do not buy new tubes from the manufacturer. Not only are they generally overpriced, but they are generally new production only because the company has to keep a large stock of known quality tubes on hand. The bigger the company the bigger this consideration.
I suggest you are doing the right thing posting on the internet for advice. Keep reading until you have the names of the handful of reliable suppliers of NOS and speciality tubes to Audiogon and Audio Asylum members.

One of the problems with tubes is once your start "thinking" that it might be time to change the tubes, your doomed, you might as well change them out because in the back of your mind, you will be always questioning the tube's performance, even if they are 100% good.

Something VERY important, when purchasing preamp tubes; being CERTAIN they are CERTIFIED LOW NOISE. ie: Upscale Audio stringently tests and grades their tubes, per their noise, microphony, and triode balance(VERY dependable). ie: (http://www.upscaleaudio.com/tubes/12ax7/ge-12ax7.html)

Some of the NOS Mullard, Telefunken, and other tubes seem to keep on going in some gear, 10 years plus, only a couple of years in other. I'm talking high hour daily use also. Usually with the good NOS ones, as long as they test good, their sound doesn't seem to deteriorate. If you plan on staying with tubes, I would consider buying a Mutual Conductance tube tester. All of the tube amp people I know have extra tubes on hand. The quality of some of the newer ones are getting better, but I don't think they've reached what some NOS ones can do. Others say they've have it down now, for sonics and reliability.