help me select a single tube to "calm down" a preamp?

I have an Audio Research LS2B. It can get a tad "strident" in the upper mid on some recordings. I am now using a Siemens 7308 / E188cc and this is good, and often great tube for soundstaging and openess, but this tube also is a little noisy, mildly bright at times and is not the last word in bass performance. Would a Mullard suit the bill?.... How about an Amperex?....Your thoughts oh kind tube-0-philes :>)
Telefunken is just what the doctor ordered for your situation.
Have you tried Kevin at upscale audio? This chap really knows his tubes and recommended a mullard for my SL-1 after I sold it to a friend...I'm sure there are others who know their tubes but Kevin comes to mind.....good luck and happy listening...Bluenose
Personaly I've had a tough time rolling tubes in my ARC LS-15. While there are a lot of good/great NOS tubes that will do the job, I find it difficult to get good examples. I still keep going back to the stock tubes. While ARC does charge a premium for their tubes, they are matched and tested. They have performed the best for me so far. At least you only have one tube to deal with. Maybe you should start with a fresh tube from ARC? Then you'll have an accurate bench mark for comparisons. Good luck....
Mejames suggestion of the Telefunken echo my first or second choice as well. Be aware that the correct number for the Telefunken version of this tube is 6DJ8. The 6922 Tele is not only extremely rare, it does not have the sonic signature to solve your problem.

Another high on my list is the gold pin Mullard 6922. Just be sure its the British version, not one manufactured in another country with the Mullard logo.

It is sometime necessary to attack this type of problem from two angles. If you list the other tubes in this unit, I will suggest replacements that work with the 6922 and bring you closer to the tonal balance and resolution you are seeking.
Go and buy yourself an Amperex Bugle Boy 6DJ8 and all your problem will be solve.
I second the vote for the bugle boy 6dj8
I believe this tube best describes the
sound you are looking for.Although i will
say,telefunkens are the best tubes ever built.
3rd on the vote for the Bugle Boy. Just be careful of "fakes".
my vote is an amperex bugle boy (select). call andy at vintage tube svcs. he sent one to me and it made all the diff in my ls2mk2. i had a siemans nos.....amperex killed it. telefunken would be a good choice too.

good luck
Hi Ho there audio pilgrim-

There is only one tube present in an LS2B and the bad news is that no matter what NOS wonder tube you choose you will not be able to get rid of the LS2B's tendency to shout and get nasty on big dynamic swings. NOS tube rolling with the LS2B realized significant gains in air and soundstaging but never really solved the nasties. The problem must lay in some other part of the circuit. Even the direct input running balanced has this problem (unlike the LS5 and other more recent ARC linestages, the '2B isn't actually a true balanced circuit) The LS5 series3 was a huge improvement over the LS2B (and a much better piece than the LS22 & LS16) but offered no practical way to deal with single-ended inputs. I was almost wooed by the SF Line3SE, a really great linestage, but fell in love with the Aesthetix Callisto and it looks like this one is going to stick. Sorry to be the bearer of bad news re- your current pre. Save your dough. Go hunt down something with the LS2B's considerable virtues but without its fatal flaw. There is a recomendation for a couple of options. Happy listening
Although I am a full tube circuit (including power supply) person, I must say that my original LS-2 (1992), in the Direct mode only, with CD playback, and with MIT Cables to the Amp, did NOT exhibit any of the nasties that have been described above. The circuit, was one of the most Neutral ever made by ARC and was even used by Chesky(I believe)to monitor playback. I ultimately got rid of the LS-2 due to my tube bias, but it worked very well with Telefunken ECC88 Gold pin. I sometimes miss the Neutrality of the LS-2. I rate it high on the ARC list of SS/Hybrid performers.........Frank
I own an LS2 MKII and have similiar results with the slightly shrill top end. A friend of mine mentioned a Dutch tube that helped tame, not cure it. I auditioned an LS5 in my home and it just brought out the natural nature of the music in resounding colors. Incredible bottom end, silky smooth mids and revealing top end without the LS2 slight glare. I'll have to wait 6 months to get one,
can't wait.

I forgot to mention. If you are using a digital front end and have digital outs on your cd player or transport, the EVS Millenium II dac will really enhance the lower octaves, leave a natural shimmer and air and musicality to the midrange and remove all the digital harshness that contributes to the slightly shrill top end. It hasn't fully tamed it, but it sure lowered the edge and provided the musical lift as significant as going to the LS 5. Now I really can't wait for the pre amp upgrade.