My thought would be a 430 or 450 volt model, but I will have a better guess once I wire a 4TK400 up to my board. I will be away this weekend due to funeral, so probably won't happen until next weekend.
I think I might go for something BIGGER like a 500 or 550 volt version to crank up some 35LR6's into the 200+ watt range for the second board.
They work pretty good and don't even get warm. A can of spray paint from Walmart can fix the ugly.
There are those 480 V industrial control xfmrs on Evilbay. Pretty cheap usually. I got some of these 500 Watters a while back for $15.
2nd picture: Warthog versus Boat_Anchor. About the same size. The industrial xfmr would normally be rated at 300 Watts at that size, but this is wound with Hi-temp materials and rated for an 80 degree C rise. Probably cook eggs on it at 500 Watts. The boat anchor is probably a 250 Watt xfmr.
2nd picture: Warthog versus Boat_Anchor. About the same size. The industrial xfmr would normally be rated at 300 Watts at that size, but this is wound with Hi-temp materials and rated for an 80 degree C rise. Probably cook eggs on it at 500 Watts. The boat anchor is probably a 250 Watt xfmr.
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I have seen quite a few of these that have 220-480v primaries and 120v secondaries. These seem if wired with 120v as the primary you would only need to find a bias and filament supply. This seems like a pretty affordable option as well. The few I have seen are in the neighborhood of 750va....pretty large.
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I used a 500VA GE 480 to 120 volt industrial control transformer wired backwards for the HV power supply in my 845SE amp. It feeds a voltage doubler made with 5AR4's. I get 1100 volts with no load, about 1050 with a 120 mA load and just over 1000 volts cranked up to 220 mA. The old Sovtek 5AR4's haven't exploded yet. I am guessing that you would get just about 600 volts with SS diodes in FWB instead of a doubler with tubes.
I have bought several of these in ratings from 250 VA to 1KVA from Ebay. The shipping usually costs more than the transformer.
Note the rated 100C temp rise at full load. How do you want your eggs?
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I got 475V when using the on-board ripple filter. If you use a more conventional filter, I would expect more.
Unlike the JJs, the Sovteks are tough. I haven't killed one yet. The SSE just arced-over a JJ one the other day. Still works, though it's sagging a bit.
I built that at least 6 years ago, maybe longer. My woodworking skills have improved a bit since I made it. Note the use of cheap pine boards and sheetrock screws.
YES, there is lethal voltage all over this thing. The tube sockets for the 845's have 1050 volts on the plate pin.
Note that the driver board is a Tubelab SE that was cooked up on the kitchen stove. I made this amp (and the Lexan TSE) before I sent the TSE out for commercial quality PC boards. I replaced the PCB in my Lexan amp a few years ago. I rarely use this amp since it is a serious room heater, so I never upgraded it......someday.
The tubes in this amp say that. I also had a 5AR4 that says "Election Tube".
When I first started buying the Chinese 845's and 211's they were $26 each. Now they are over $50. Maybe I could sell a few. I think the 300B's have doubled too.
I also have a carton of early Chinese KT88's. They are at least 10 years old, probably closer to 15. They remind you that the Chinese invented fireworks. These have shown me that is it possible for a tube to blow so violently that the glass broke! I got to get some from the warehouse and crank them till they blow....with the video camera on of course. Good Youtube footage. The blue death ray tube would have been cool in video.
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Indeed. I believe I paid <$100 for the quad. This was probably about 8-10 years ago.
The Shoogoo stuff has gone up as their reputation has improved. Now they have these fancy "Psvane" and "Treasure" types. I can't get over all the fake NOS stuff they have put out over the years, and so I can't help but feel like these premium tubes are just a gimmick. I kind of feel the same way about the Tung-Sol and Mullard reissues. Some of New Sensor's reissues seem to be unique (based on how they look/feel), but others leave you wondering if they are just normal Sovtek stock that was maybe binned during test and then labelled differently. It seems to be working for them, so I guess I cabn't complain.
That would be cool. My first experience with Chinese tubes was about 10 years ago when I tried to retube my Thomas amp. The new 6V6GTs of the day did not handle over-spec B+ and these failed quickly and violently at 320V B+ (fixed bias). NOS tubes were more plentiful at the time, so I got some JAN tubes and those rocked. I guess the new stuff is better.
More than one person has commented to me about short life or outright failure of reissue Tung-Sol KT88's in the Simple SE. The EH and Sovtek tubes seem to take anything thrown at them. Obviously something is different, and not necessarilly in a good way.
I built some guitar amps that used the same Allied 6K7VG that I use in the SSE. B+ was about 450 volts. I had been using Sovtek 6550WA without issue, but I got these KT88's cheap. The first pair glowed and died early. The second set worked on the bench, but when I set the amp head on top of the speaker and cranked it, the fuse blew. After a few blown fuses, I stuck a screwdriver in the fuse holder, dimed the volume control and cut loose. A most wicked firestorm errupted in one of the 6550's leading to broken glass. I put the Sovteks back in and all was well. The Chinese KT88's worked OK in some HiFi amps that I made that ran on 380 volts. They still died early.
I have found some rather poor quality in late vintage Sylvania tubes too. I got a brand new bulk pack of military surplus 6V6GT's, and when I opened it I found that nearly half had gone to air. In the 10 years that I have had the box stored inside my air conditioned house several more have gone to air. Many that look OK have the blue glow of gas. I posted pictures of some 35LR6's that were so poorly assembled that they never could have worked. Now I have looked at all of the NOS 6KN6's that got last week, many of them are assembled bad. They may work, but they won't live long.
Are you talking about the Tung-Sol 6550 (big, ST shaped bottle like the Sovtek KT88) or the ultra-premium "Genelex Gold Loin" KT88? I had a Tung-Sol die in my SSE recently. I can't quite stomach the cost of the Genelex.
Those are the ones that die, and you are not the only person that has seen it happen. Some users like them so the problem could be batch related.
I know of two users that put these in their SSE's. Both said that they sounded great, but I have not heard anything since the initial build.
I still have the original pair of EH KT88's in my SSE. That amp saw daily use for about 3 years, until my SPP was finished.
They were a quad meant for a PP amp. I actually used them in my ST70 for a while, but they were a little tough for the VTA70 driver board to drive. Now I guess they will be for the SSE. I won't be buying any more. One of the 3 remaining has some blue on the glass above one of the plates. The others don't have it, so I agree there must be some build consistency issue. They sound the best when pushed hard (100mA), but I backed-off after this incident. I guess I'll just keep leaning on them and see what happens. No point in not using them in the way that they sound their best.
The SED KT88s sound very nice too, but can't handle as much current and don't quite have the bass punch of the New Sensor tubes.
Wow...sorry for the OT again.