ARC LS2 tube life?

Tubes lose their luster and/or get noisy when they are ready for a change. Unless you are trying to change the sound in your preamp I would use either NOS Sovtek6922's or 6H23EB's. I find the current Sovteks a bit too cool. If you want a different sound tell us what you want to do - someone will have a suggestion.

Sounds like you could use a new tube. The 6922 has an average expected life of perhaps 7-10K hours, but this will depend upon what you are driving with them. Your LS2B does not tax that single tube much at all in my experience. My friend had a stock LS2B where the tube (I think it was a Sovtek) did not go bad for eight years. He travels a lot though so probably the unit had light use. Using the pre regularly anywhere from 2-3 years might be normal.

Upgrades: There are some great NOS tubes out there that you can spend plenty of money on. Since you only need one you can likely find a deal on someone selling a solo. Since my friend has a stock LS2B and I have a modified one we've done some side-by-side testing and tube rolling together. As expected the better tubes were the NOS Siemens cca's and the Telefunken. Mullard and Amperex Holland did not make the cut. My friend's now hooked on those Russian Rocket tubes that are a more hearty replacement. Kevin at Upscale seems to also like those as I've seen many happy posts from folks taking his advice on them. I think they are 6H30's. No personal experience there, but I do respect my friends opinion and he likes the results in his stock LS2B. As far as more expensive upgrades go, I can highly recommend the upgrades by Steve Huntley at Great Northern Sound. My LS2B was upgrade by them and the difference when we swapped out the stock unit in my friends system was immediately apparent: better focus and imaging, slightly wider and deeper stage, and improved clarity. Both of us agreed it was worth every penny. I went for the Standard Level upgrade which was around $800 as I recall. He also offers a Reference Level for almost double the price. Steve used to work for ARC, and then went over to Wadia and worked there for some years. He now owns GNS and does some highly respected modifications on components from both monikers. You can check out their basic website here. No affiliation, just a happy customer.

Marco

6922's tend to last longer than many other types. I've gotten over 5years out of my current pair and they still test 85%. They can change the sound drastically and last a long time. Go buy a pair of telefunkens for $75 to $90 and forget about them for a while