It's Time To Change ARC SP-11 Tubes When.....

I bought this preamp about 3-4 years ago with brand new tubes and have not used it a lot.

Lately, however, I have been leaving it on 24/7.

(Maybe I am imagining things, but I would say my system sounds dramatically smoother when I leave the amps on.)

In the 24/7 mode, how frequently would you recommend changing the preamp's tubes?

When these tubes begin to deteriorate, what are the clues?

More noise? Changes to soundstage? Less detail?

I have a new set waiting in the box from ARC. Sounds pretty good to me now, but wondering if it should be even better.

Well, your tubes should last approx. 2,000 hours.

2,000 devided by 24 = 83 days.......

Kinda costly if you ask me..............
OOPS......... Wasn't thinking correct (or spelling correctly). Pre's have an average 5,000 hours, not 2,000.... so...... 5000 divided by 35 = 208 days, or 7 months......

Sorry about that.
I recall from the reviews in TAS and Stereophile that ARC felt if you left the unit on all the time it would sound best, but you'd need to replace the tubes every 9 months or so. It's possible using better quality tubes might extend that life. Tough to tell when they're gone, because the sound deteriorates gradually so you don't notice the difference as readily, but in my case my system started to sound a little lifeless, lacking dynamic punch and clarity. There will definitely be more noise as well as the tubes start to go. And watch out for pops and sputtering!
When I owned my sp11 ( for 4 years ) I put them on in the morning upon getting up. Shutting down at bedtime. No need to leave them on any longer.I got about 1-/2 -2 years before changing....
What model of tube are we talking about?

Yes, what model would be best?

And lets assume, in the worst case scenario, we do, in fact, change them every 6 months?

How much is that per month?

Compared to drinking good wine or something?

Dont know the numbers but guess it would be well worth it!
I finally changed the tubes this weekend -- my first experience with this.

After posting this thread and reading your responses, I think I was determined to burn out my old set to better understand how tube degradation sounds.

Having purchased the SP11 in 02 (?) I was thinking that the tubes were at least 3 years old.

And although I often left the system off for days at a time, there were other times when I left it on 24/7.

For the last 6 weeks or so, the tubes have also been left on 24/7.

I am still curious to think that they didnt sound that bad, other than some occasional squeaky sputtering and some bloat in the bass.

My main curiosity pertained to the fairly flat image that I have and I wondered if new tubes might increase the illusion of depth in the soundstaging.

The bad news is that the image is still pretty flat, something I hope might be changed with new cables.

The good news is WOW -- subtle in a way, but ultimately a huge improvement.

Everything seems much more nuanced, more air and separation between instruments, breathier detail with vocalists, no more pops or squeaks and bass seems tighter and more defined with less boomy bloat.

I guess I needed new tubes?!
I had the same pre for about 10 years. Initially I left it on 24/7 and changed out the tubes very 9 months or so. Later I did like Thorman, turned it on when I got up and off when I went to bed. I also usually got different tubes for the one's associated with the phono circuit but you don't currently have that issue.

The flat imaging is probably a function of your cables and your amp, assuming you still have the 23.5 which while extremely quiet and powerful, never struck me as an imaging champ. Good for its day and lots of slam for those Maggies but maybe time to look for something different. FWIW, I replaced my SP11 with an ARC LS-15. The LS-15 was much better at the frequency extremes, imaged better and had greater dynamics, ie no contest.