preamp tube hiss from my SF Line 1

Brf: I swapped out one tube at a time using an extra tube I had. I've actually tried a few "extra" tubes, swapping out only one a time and get the same result. My next step is to put all six stock tubes in it and see what happens.

Jea48: You wrote: "If you put back in the three tubes you had pulled before the hiss, and you still have it, then I think that eliminates the tubes from the equations." I'm not following you. If I put the same tubes back in and the hiss is still there I don't see how I ruled out the tubes. If it is a bad tube, then wouldn't putting it back in cause the hiss to continue? The hissing didn't start until after I swapped out a pair of tubes. Maybe I did in fact break a solder joint. There aren't any error lights on though..

Phd: Did you happen to get an estimate on the repair work? The hiss is very audible and I won't be able to live w/it. Thanks for the info.

Thanks for all the suggestions. I'll update the thread after I swap out all six. I've had good luck with SF / Anthem tech support so I think it's time to shoot them an email as well.

One more piece of information. The hissing doesn't start until about 1 minute after the input is anything other than SSP. Assuming the starting point was the SSP or coming out of standby. This happened every time after I swapped out a tube trying to diagnose the issue earlier in the week. The previous instances were after powering the pre, this time the same thing happened after switching the source from SSP(HT passthrough) to the CD player. The pre has been running for a few hours so it's nice a warmed up. It seems more and more relevant considering it's a consistant issue after about a minute.

I've been tied up this week. Plan to swap out all the tubes in the next day or two. I'll update the thread with my findings.

No update yet. Hope to get to it this week.

I finally got around to working out the problem today. SUCCESS!! The problem was due to noisy tubes. I had one very noisy tube and one of my spare tubes of the same type, Amperex Jan Green, was also very noisy. Luckily I had a few more good spares and was eventually able to find 6 tubes that were dead quite. Funny thing is I ended up with the same setup I was running before all of this business started up. Amperex Jan Greens up top, Amperex USA Whites in the middle and a pair of Russian Rockets (not sure what they are) in the bottom pair. It was the bottom pair I tried swapping out when all of this started up. I put my Herbie tube dampers back on and I'm back in business.
Thanks to everyone for their interest and help.

Jea48: I remember one of your previous threads concerning the order of importance and yes, that's how I have them. I run the tube dampers about 25% the way down from the top. I didn't play around with placement much as the concensus seems to be towards the top like you mention. Any experience or have you heard comments concerning some of the new EH gold pin tubes in the SF line? I'm curious about how they might sound. At $15 a pop for brand new tubes, it's tempting. I've read that their production quality has really been improving, whatever that means.

Brad

My problem turned out to be two seperate tubes were making noise. It took a while to troubleshoot, luckily I had a nice stash of extra tubes to mix and match while trying to isolate it. I'd just replace the problem tube unless they are inexpensive and you think they are getting up there in age.