Do new NOS tubes need break-in/running-in?

No changes after 5-10 hours of use.

Thanks for the responses. Usually I check the archives before posting but this time I'm little impatient I guess.

I've owned Sonic Frontiers Line 1 and find it to be not sensitive to tube rolling at all. I will try to run-in the tubes longer and hopefully the ARC will not exhibit this similiar trait. Well Onhwy61, your system looks great too.

Tubes can take up to 100 hours to break in, there is no set time so just wait it out.The rectifier tubes in my Art Audio Diavolo took 200 hours. There where also many Mullard tubes labeled with the Amperex label, so they may be the same tubes. You definetely will hear a difference between a Mullard and a Amperex.If you do not,they might be the same tubes. To answer the question regarding the Audio Research LS-16, yes,the tubes make a large difference.I preferred the Mullards, but that is my taste.
Mike

I have rolled small signal tubes quite a bit, especially 6DJ8-E88CC-6922-E188CC-7308 types, and found that a tube's "flavor" shows more or less immediately, in minutes, but the flavor usually develops, so to speak, over the next 5-6 hours; sometimes more, but I can't remember a small signal tube that's changed much after 12 hours.

I wonder if the process with tubes is really a "break in" or a thorough "warm up." Tubes heat to operating specs quickly when they are used in a component, but NOS tubes have been on the shelf for quite a while, so I wonder if they're really just waking up, as it were. The time may vary with whether the piece is designed to be easy on tubes or not. 'Not sure where your ARC piece falls in that continuum. The difference between break-in and warm up may be semantic, but maybe not. With tubes, I've never heard the kind of fundamental change that I've heard with other components. When I first played my Virgo 3s, for example, I thought I had made a very expensive mistake, but one morning I woke up and they sounded great. Similarly, anything I've owned with Blackgates hasn't shown is most developed mellifluousness until it hits the 200 hour mark -- and then some. For me, at least, I've never heard that kind of changes in tubes. Again, ymmv.

But Majicjazz may have hit the nail on the head. Tubes branded Mullard or Amperex may actually have been made at the same factory. The way to tell is by looking at the second line of the etched codes on the side of the tube, near the bottom. If the second line begins with an asterisk (*), then it was made at the Amperex factory in Hicksville, NY. If it starts with a sideways triangle (almost like a delta symbol), then it was made at the Philips factory in Heerlen, Holland. If it starts with a B, then it's from the Mullard factory in Blackburn, UK. It's very common for tubes branded Mullard or Amperex to have been made at the Heerlen factory. If your tubes sound the same, that may be the reason. My .02, as they say. Hope this helps.

I am little relieved after reading the post by Majicjazz. At least now I know the ARC preamp will be quite receptive towards tube rolling.

Thanks for the comprehensive post Jbaxley. I will see if I have time to check on the etched codes on the Mullards this weekend as it requires a bit of work to unplug everything and get the piece out from the shelf. Hopefully they are not the same Amperex tubes as I paid quite a bit for the NOS.