What tubes to use for Audio Research SP-9 MkIII?

I have never opened the case on my AR SP-9 MkIII preamp. I called the guy who sold it to me and he says that it has Sovet6922 or called 6DJ8. A pair of Simens old new stock tubes 6922 made in Germany are for sale for $130 bucks...is the price of the Siemens tubes a good deal? Will the change in tubes make a significant improvement? I've never opened the case...how many tubes will I need? The AR users manual suggests leaving the preamp on all the time....how long will tubes last if the unit is always left on? Thanks,...Mitch
I have the MKIII and NOS tubes are the way to go. The tube near the center of the circuit board is for your cd, tuner etc. The other tube is for the phono stage, so if you don't have a turntable you'll need just one tube. No, $130 for two Siemens is a bit high. You can get "made in Germany" RCA 6922 for about $25 - $35 apiece on Ebay. They were made for RCA by Siemens. The Siemens give an open, detailed sound at the expense of the bottom end heft. At the other end of the spectrum is the Telefunken E88CC (6922 European) and it will give you hefty bass and smoother sound but less detail. They run about $65 - $100 apiece. Amperex 6922 is somewhere inbetween those two but there are many versions of them, all designated 6922, and some are much better than others. Try audioasylum.com, FAQ, "Joe's tube lore" for more info on that. If you play music every day then leave the unit in "mute". That keeps the heater on so the tube doesn't have to cycle hot, cold, hot which is hell on tube life. The 6922 family is rated at 10,000 hours. Whether standby time (mute) is counted towards that, I don't know - info Anyone? Good luck.
I've had my MkIII for about 5 years and have tried Telefunken,Mullard,Amperex,etc. I finally called ARC and got some of their stock tubes for the preamp, the Sovtek 6922. I use them with their tube dampers and to me the preamp has never sounded better. I'd suggest that you call ARC, tell them what equipment you have, the type of sound you're looking for, and they'll be able to help you. New tubes from them are about $25-$30. Another source for tubes and info is Upscale Audio.
Good listening.
Upscale won't sell any decent 6dj8/6922 types to people unless they bought their gear there. I'd recommend Amperex as the best tubes of this type...after all, they invented the 6dj8 frame-grid type of tube.

-Ed Sawyer
(Full disclosure: I have some of these for sale.)
I second the AR tubes having owned the SP-9 and they do sound their best with tube dampers.
In my experience ARC ls16,sounds best with the stock sovteks.Tried siemens69229-detail NO bass) & matsushita's 6dj8,(no improvement just noisy)I think ARC preamps are sensitive to nos tubes in general,besides the rip-off factor is too high dealing with these "internet guru's of tubes".
My favorite tube in the 6DJ8 family is the Telefuken E188CC.
It is very detailed and laid-back (if this is the sound you are looking for). Siemens CCAs has more bass, and Valvo E188CCs is detailed but a bit forward. Amperex made many differnt types ranging from 6DJ8,6922,7308 Bugle Boys,PQ,USN,CEP,Gold Pin,World Globe,pinched tubes,made in USA, Hollad A getter& D getters (BTW D getter tubes are mellow sounding tubes)

Anyway, all this is quite maddening. I agree with Wlutke, these tubes can get very expensive, and Ebay is a good source to obtain some of these tubes for a listen. Good Luck!
BTW, here are the US and European equivelent #s for these tubes. 6DJ8-ECC88, 6922-E88CC,CCa, 7308-E188CC, the E288CC european tubes are physically longer in length and have a longer life span. There are also US JAN and British CV military tubes as well.
I am using Gold Aero Platinum, Gold Pin 7308 tubes in my SP9 Mk II. Sounds very much better than Valvo 6DJ8's.
Sorry for tagging on to this thread, but I also would like to know what you would suggest for tube's for my LS 25 mkl and PH 3SE. And....should we keep the pre-amp's and phono amp on (mute) if we listen 1 hour a day???

I welcome your responses!