Hi all! I've just bought an used Ampeg SVT-3 and Ampeg 115 classic cab. I'm really enjoying the sound, it's a big leap from my previous rehersal rig. But after a rehersal where I was really pleased with the bass sound (and the amp was all flat!), I noticed how the amp always had some distortion... Now I know a tube amp should give a nice smooth distorted sound that lots of people enjoy, I find it strange that no matter how I change the amp settings I cannot get a pure, clean tone. I tried 3 basses, a warwick 5-str corvette $$, a tune 4-str bass maniac and a cort 4-str acoustic. All of them distorted the amp. So, I'm asking you fellow TB'ers for help. Please Since I hear the distorted sound even from the amp DI, I guess all the distortion is coming from the (tube) preamp stage. The previous owner never changed the valves and, according to the pcb, the amp is from 93. But, the previous owner said he tested the valves (he has some sort of valve testing machine) and they are all ok. But I have talked to him and he aggrees that there may be a problem with the valves being old, and barely used. Well, since the previous owner had to remove the tubes to test them, it's possible he mixed them up... So, heres a pic of the amp. There are 4 12AX7 valves, and one 12AU7 which is in position 2. Is it correct? If not,where should it be? Or maybe this isn't the problem at all. Next thing to do is to replace the tubes, but I don't have the replacements yet.