seti Posted August 27, 2008 Share Posted August 27, 2008 What order would you tube gurus upgrade these tubes? Which function would you select primo tubes for or are they all equally important? Power: 4 x 350B Preamp: 2 x 12AT7 Phase Inverter: 2 x 12AU7 Driver: 2 x 6922 Currently I have ValveArt 350B, Mullard formerly NOS 12AT7, generic chinese 12AU7, and generic chinese 6922. I replaced the tubes I understood the most premap and power. I' m still abit fuzzy on the other two functions. Time to do some more reading. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted August 27, 2008 Share Posted August 27, 2008 I'm sure you don't wanna pony up for NOS 350B's, so I'd work on the phase splitter and driver tubes. All I can say is you can probably do better than the Chinese ones that are currently in use. You can source a 12AU7 rather cheap over 6922/6DJ8. They'll be a little more expensive. I've got a bunch of 12AU7, I'd have to sort through them to see what I have.....I know I have a pair of Admiral labeled RCA side getter cleartops still plenty strong....I'd have to see.... Quote Link to comment Share on other sites More sharing options...
seti Posted August 27, 2008 Author Share Posted August 27, 2008 I'm sure you don't wanna pony up for NOS 350B's, so I'd work on the phase splitter and driver tubes. All I can say is you can probably do better than the Chinese ones that are currently in use. No way man. WE350B let me take out a loan. The amp can run most 6L6, 5881, and KT66 varieties. One of my favorite features of the amp. You can source a 12AU7 rather cheap over 6922/6DJ8. They'll be a little more expensive. I've got a bunch of 12AU7, I'd have to sort through them to see what I have.....I know I have a pair of Admiral labeled RCA side getter cleartops still plenty strong....I'd have to see.... I picked up rca clear tops but they were noisey as hell. They must have been just used up. I was curious what you guys consider the most important in the tube chain. Quote Link to comment Share on other sites More sharing options...
oldbuckster Posted August 27, 2008 Share Posted August 27, 2008 Seeing that your asking tube questions, let me ask one: What is a good rectifier tube to replace an 5 AR 4 ? Quote Link to comment Share on other sites More sharing options...
seti Posted August 27, 2008 Author Share Posted August 27, 2008 The last rectifier I bought was national unoin brown base 5r4 but I don't think you can sub them. Here are some prices for you to check out. I usually buy what I can afford at the time. http://www.vacuumtubes.com/5ar4.html Quote Link to comment Share on other sites More sharing options...
mike stehr Posted August 27, 2008 Share Posted August 27, 2008 I picked up rca clear tops but they were noisey as hell. They must have been just used up. I was curious what you guys consider the most important in the tube chain. Yeah, that doesn't suprise me. I not much of a fan of 12AU7 anyway. So what do you find objectionable about the overall sonics of the amp, to warrant tube rolling? All tubes are part of the tube chain. Pull one in use and you'll find out how important it is. I would think it would be a matter of rolling the driver and phase inverter tubes, with the driver tube (maybe) being the one that changes sonics the most? A matter of experimenting? Quote Link to comment Share on other sites More sharing options...
seti Posted August 27, 2008 Author Share Posted August 27, 2008 I picked up rca clear tops but they were noisey as hell. They must have been just used up. I was curious what you guys consider the most important in the tube chain. Yeah, that doesn't suprise me. I not much of a fan of 12AU7 anyway. So what do you find objectionable about the overall sonics of the amp, to warrant tube rolling? All tubes are part of the tube chain. Pull one in use and you'll find out how important it is. I would think it would be a matter of rolling the driver and phase inverter tubes, with the driver tube (maybe) being the one that changes sonics the most? A matter of experimenting? The amp came stock with cheap chinese tubes so I wanted to roll them out. Not sure how many hours are on them as well. Well I started with the power tubes just because I wanted to try the VA350B and they were an improvement over the chinese 5881. Yes I know the VA are chinese as well but they have been better than expected. It seemed logical to do the preamp tube next so I did. I thought there would be a more methodical way to go about tube upgrades instead hey tube your next Thanks Quote Link to comment Share on other sites More sharing options...
seti Posted August 27, 2008 Author Share Posted August 27, 2008 What order would you tube gurus upgrade these tubes? Which function would you select primo tubes for or are they all equally important? Power: 4 x 350B Preamp: 2 x 12AT7 Phase Inverter: 2 x 12AU7 Driver: 2 x 6922 As a rule of thumb, I find that the importance runs from the front (first tubes) of the signal chain to the back (power tubes) as far as what will make the most improvement in signal quality. i.e. start with the 12AX7. Power tubes last interesting. I've already upgrade the 12at so I'll hit the 12au next. Maybe I'll talk to brent jessie and get an assortment of tubes. Has anyone tried the KT66 Gold Lion reissue? Thanks Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 29, 2008 Share Posted August 29, 2008 My Favorite 12AU7 is the Mullard box plate CV4003.... been running them for years as a phase inverter. They used to be some what affordable at about $35 a tube but supplies of this 1980's military tube have dwindled and the prices have nearly doubled in the last few years... Craig Quote Link to comment Share on other sites More sharing options...
seti Posted August 29, 2008 Author Share Posted August 29, 2008 My Favorite 12AU7 is the Mullard box plate CV4003.... been running them for years as a phase inverter. They used to be some what affordable at about $35 a tube but supplies of this 1980's military tube have dwindled and the prices have nearly doubled in the last few years... Craig Brent Jessie has the Mullards you mention but only has one in stock but he gets new stock often. I have had good luck with him so far. CV4003 / 12AU7WA Mullard boxplates, Great BritainMATCHED PAIR New Old Stock original military box. This is a nice matched pair of vintage British military 12AU7 boxplate tubes, with the outstanding Mullard quality. Singles are $45 each. $100.00 per pair 1 single UpscaleAudio has then for $30ea. Have you tried the Gold Lion KT66 reissue? It looks nice. Thanks Craig. Quote Link to comment Share on other sites More sharing options...
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