Allan Songer Posted December 28, 2005 Share Posted December 28, 2005 I have some of these and they are really nice tubes--right up there with the GEC U52 and the WE 274B. World War II Surplus. http://cgi.ebay.com/Pair-of-Sylvania-Tube-274B-NOS_W0QQitemZ5846048405QQcategoryZ67816QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Quote Link to comment Share on other sites More sharing options...
Timmikid Posted December 28, 2005 Share Posted December 28, 2005 THanks Allan, I might have a go at these! Are they plug in, no matter what other tubes are in? Quote Link to comment Share on other sites More sharing options...
Allan Songer Posted December 28, 2005 Author Share Posted December 28, 2005 Direct plug in replacement for the 5U4. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted December 28, 2005 Share Posted December 28, 2005 http://tdsl.duncanamps.com/pdf/vm408.pdf Quote Link to comment Share on other sites More sharing options...
Timmikid Posted December 28, 2005 Share Posted December 28, 2005 Thanks 3D, I am just not technical enough. I just see lines and many very depressed smilies. [:$] Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted December 28, 2005 Share Posted December 28, 2005 Direct plug in replacement for the 5U4. the 274 is not a replacement for the 5U4 but the 274 is similar to the 5R4. The 274 a WE tube is required by spec to be used with a center tapped 5V heater. The output to be drawn from that center tap. In this way the the direct current is equal on both halfs of the directly heated filament. The WE274 won't blow up but you might kill it faster if your amp don't do this. According to the schematic I have for the MC30, it doesn't use such a center tap. At the price a pair of WE274 goes for these day, I'd be cautious. Quote Link to comment Share on other sites More sharing options...
Allan Songer Posted December 28, 2005 Author Share Posted December 28, 2005 Well, I've run the WE 274B in a pair of MC30s for about 2500 hours and they're still working (and testing) as new. The 274B isn't a 5R4 or a 5U4--it's somewhere inbetween. I think you would have to be far more brave to plug a 274B into a 5R4 circuit--the 5R4 can take 750V, while the 5U4 and the 274B are rated at 500v.The 5R4 draws 3 amps, the 274B 2 amps and the 5U4 2.25 amps.All I can tell you is that the 274B works great in an MC30--but you guys are the electronics wizards--I'm just a hack with a soldering iron who can barely read a schematic!!They really, really sound GOOD. Why do you think they work so well?I got them in a big bulk purchase of tubes, so I have about ten bucks a piece into them--I too would not spend the hundreds of dollars each these sell for. I got the Sylvania 274B in the same lot.I wouldn't pay more than $75 ea for the Sylvania ones. Quote Link to comment Share on other sites More sharing options...
neo33 Posted December 28, 2005 Share Posted December 28, 2005 Jeff, having a PhD, doesn't entitle you to know everything. [] Quote Link to comment Share on other sites More sharing options...
Timmikid Posted December 29, 2005 Share Posted December 29, 2005 They went way over my head at $115.- [:|] Quote Link to comment Share on other sites More sharing options...
paul cbc Posted December 29, 2005 Share Posted December 29, 2005 Allan, Any thoughts on how these compare to a Mullard CV 378? Paul Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted December 29, 2005 Share Posted December 29, 2005 Well, I've run the WE 274B in a pair of MC30s for about 2500 hours and they're still working (and testing) as new. The 274B isn't a 5R4 or a 5U4--it's somewhere inbetween. I think you would have to be far more brave to plug a 274B into a 5R4 circuit--the 5R4 can take 750V, while the 5U4 and the 274B are rated at 500v. The 5R4 draws 3 amps, the 274B 2 amps and the 5U4 2.25 amps. All I can tell you is that the 274B works great in an MC30--but you guys are the electronics wizards--I'm just a hack with a soldering iron who can barely read a schematic!! They really, really sound GOOD. Why do you think they work so well? I got them in a big bulk purchase of tubes, so I have about ten bucks a piece into them--I too would not spend the hundreds of dollars each these sell for. I got the Sylvania 274B in the same lot. I wouldn't pay more than $75 ea for the Sylvania ones. The 274B is a 274B indeed. A little correction is in order. The 5R4 and the 274B draw 2 A. The 5U4 draws 3A. The 5U4 can be used with input capacitor up to 32 uF, 40 uF for the other variants (5U4G, GB, etc.). The 5R4 and 274B should be limited to 4 uF input cap. The MC 30 uses an 8 uF input cap. The 274B is used outside its rated limit in the MC30. Does'nt mean the 274B will burst into flame after you flick on the switch. You may get 3000-4000 hours out of them. Even more. Used within it's limit, you'll get 10 000 hours with no sweat. Since I'm starting to sound like a well known member of this forum, I'll stop it right here. As for why they sound good... First suspect would be the possibility that these may get the B+ to a particularly sweet sounding operating point for the amp. Second suspect is that the WE274B were made by Western Electric which, to me, was the best tube manufacturer ever. Quote Link to comment Share on other sites More sharing options...
Allan Songer Posted December 29, 2005 Author Share Posted December 29, 2005 Well, even if I may be using them up too fast I'm still going to use them!! When they're toast I'll move back to the U52--they sound pretty good too. Maybe the synergy between the 274B and the 350B has something to do with it? WE with WE (especially good when Sonny Criss blows "Wee"). Quote Link to comment Share on other sites More sharing options...
steamer Posted December 29, 2005 Share Posted December 29, 2005 Check these babys out! http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5847252392&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1 Greg Quote Link to comment Share on other sites More sharing options...
Timmikid Posted December 30, 2005 Share Posted December 30, 2005 Check these babys out! http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5847252392&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1 Greg Gargl! [:^)] Quote Link to comment Share on other sites More sharing options...
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