Matthews Posted January 8, 2016 Author Share Posted January 8, 2016 (edited) "Rectifier selection switch with dropping resistor network. Unloaded, at idle." Edited January 8, 2016 by Matthews Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted January 8, 2016 Share Posted January 8, 2016 Too bad those are 5V rectifiers. 1 Quote Link to comment Share on other sites More sharing options...
Matthews Posted January 8, 2016 Author Share Posted January 8, 2016 Too bad those are 5V rectifiers. "What should they read, unloaded at idle?" Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted January 9, 2016 Share Posted January 9, 2016 (edited) Hey Matt, that's the filament voltage and it should read 5V. He's got the green wires wired to the switch, if it's a Hammond Power transformer the wires to the switch should be Yellow, in fact most tube transformers will have the 5V winding as yellow. He's using the 6.3 winding which is wrong. I would also recommend pulling the B+ from the 5V winding center tap. Edited January 9, 2016 by xxJPMxx 1 Quote Link to comment Share on other sites More sharing options...
Matthews Posted January 9, 2016 Author Share Posted January 9, 2016 He's got the green wires wired to the switch "The green wires are coming from the separate, 5V transformer". Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted January 9, 2016 Share Posted January 9, 2016 Well regardless, there is 6.3V which isn't a good thing for those tubes. Quote Link to comment Share on other sites More sharing options...
Matthews Posted January 9, 2016 Author Share Posted January 9, 2016 Well regardless, there is 6.3V which isn't a good thing for those tubes. Perhaps they will catch on fire? Be a good light show, "regardless", aye? Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted January 9, 2016 Share Posted January 9, 2016 Hey Matt, I noticed the quotations around the responses and figured they were from toolshedmatt. Did he figure out what's going on? He kept saying that the reason for them being high is because they were unloaded? That doesn't make any sense because in the picture you can clearly see the filament is lit which means the filament winding is being loaded. I am not sure if he thinks that the 10mA of current being drawn from the 6J5 tubes will drop it? That current will be drawn from the high tension winding through the rectifier and will not drop the filament voltage. Will you see fireworks? Probably not. Will the rectifier tube wither away prematurely? Most likely. 1 Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 9, 2016 Share Posted January 9, 2016 (edited) A retired EE friend taught me a bit of a way to rejuvenate a tube with lower emissions. It mostly only works with directly heated tubes. I've tried with indirectly heated tubes, with some if little luck. It's the same theory as how they rejuvenate a worn out television tube...if there is some contamination or a poisoned (probably the same thing) cathode, they crank up the heater voltage and try to boil (strip) off the contamination off the cathode. I'm not aware of the exact process of going about it, nor do I have any business doing it, because it can be rather dangerous...I think it involves a cap as well. It's hit or miss, the TV tube may recover or may forever be dead. To do this with a almost wanked directly heated triode, or one with a possible contaminated filament, stick it in a tube tester and crank up the filament voltage. Let it cook for awhile. I've done it, and it does work. But again, it's hit or miss. A dead tube is a dead tube... Think about it, all them electrons just boilin' off that cathode in a big ol' hurry... Edited January 9, 2016 by mike stehr 1 Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 10, 2016 Share Posted January 10, 2016 Well regardless, there is 6.3V which isn't a good thing for those tubes. This is a very valid point. Premature tube failure is often caused by excessive filament voltage. Most tubes can handle voltages which are up to 10% high, but around 28% high is dangerous from a longevity standpoint. This is a common problem with modern power and filament xfmrs which are often designed with 115V primaries. Maynard 1 Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted January 10, 2016 Share Posted January 10, 2016 This is a common problem with modern power and filament xfmrs which are often designed with 115V primaries. Hey Maynard Yes a lot of times people will buy modern transformers with the primary wound for 115, if the secondary load is rated properly this will still only get you 5.2V-5.5V. To get 6.4V with a 5V winding you would need to see something like 145v wall voltage!!! Or there are multiple primary taps and the 100V tap was used with 120v wall volts, this would still only get you 6V. Either way it should get straightened out or else some good vintage bulbs will be unhappy. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 10, 2016 Share Posted January 10, 2016 (edited) I'm starting to wonder if this some sort of a joke. A 5 volt directly heated rectifier tube is shown in the photo with a multi-meter supposedly hooked up to the filaments. It shows 6.3 volts, unloaded at idle. That makes no sense. A loaded rectifier tube isn't going to drop the filament/heater voltage. I may be some schmuck hobbyist, but I've never experienced that. I figured my last post being a little off-topic would however demonstrate what happens when exceeding the filament/heater voltage of a vacuum tube. Electrons are boiled (in a evaporation process) from the cathode until the material ( a type of aluminum oxide or such) is eventually gone along with the tube's emission. A directly heated tube just has a filament (no cathode) treated with the same sort of material, (sort of, not really) which boils/evaporates from the filament in the same manner. Now running a directly heated 5 volt rectifier at 6.3 volts is going to shorten it's life. No tube data says you can, either. You can, but it's like burning a candle with a propane torch, it won't last that long. You sure you want that 5 volt rectifier tube (heated at 6.3 volts) eventually lose it's emission, which a chance of a short? Being directly heated, it could take a few things out with it if it does. (more than likely will happen upon start-up or shut-down of the unit.) I don't get it... Edited January 11, 2016 by mike stehr Quote Link to comment Share on other sites More sharing options...
Matthews Posted January 20, 2016 Author Share Posted January 20, 2016 Matt's exquisite attention to detail continues to amaze me. His craftsmanship, discipline and patience is quite remarkable. The back input plate is no exception.. This entire build has been quite the pleasure. Matt has kept me posted routinely with his progress, sometimes daily. He sends me photos and an explanation of what I am looking at (sometimes in laymans terms per my request). Not only has Matt fascinated me with his craft, he has become a friend. The personal experience he has so graciously offered is priceless. I am excited for the day to come when I can meet him in person, shake his hand and say, hello friend. As this build begins to come to an end it is a new beginning for me. I will long look back upon this experience in fondness. Thank you Matt of Tool Shed Audio. With a "smoke test" in the coming day, mere days to my door, Exodus will finally be home, right next to her twin brother, Genesis. Yeah, I am a little excited... 1 Quote Link to comment Share on other sites More sharing options...
woodsman Posted January 20, 2016 Share Posted January 20, 2016 I put my faith in Matt last year and he built me a 6 watt SET amp. Than one is named Emotive 5i. It is the best sounding amp I have ever owned. I am really amazed at the volume's it can reach and play with such authority from a mere 6 watts. Build quality is way above and beyond any piece of gear I have owned as well. You will NOT be disappointed. I am glad I found this thread, I ordered one of the covers for mine. Thanks for getting that out there. 3 Quote Link to comment Share on other sites More sharing options...
woodsman Posted January 20, 2016 Share Posted January 20, 2016 Here is the front 2 Quote Link to comment Share on other sites More sharing options...
woodsman Posted January 20, 2016 Share Posted January 20, 2016 Side view Quote Link to comment Share on other sites More sharing options...
woodsman Posted January 20, 2016 Share Posted January 20, 2016 Better side view 2 Quote Link to comment Share on other sites More sharing options...
Matthews Posted January 20, 2016 Author Share Posted January 20, 2016 Better side view Thanks for posting "woodsman"! That is really nice. Matt's builds are a breed of their own. It is cool how much different yours is from the Genesis & Exodus. Is Emotive an integrated? 1 Quote Link to comment Share on other sites More sharing options...
woodsman Posted January 20, 2016 Share Posted January 20, 2016 Yes, it is an integrated 1 Quote Link to comment Share on other sites More sharing options...
Aercool Posted January 20, 2016 Share Posted January 20, 2016 Agree on all points that Matthews states while working with Matt. My Trancendence 12 is still a joy, and now I wish all you people would leave him alone so I can start a preamp project with ME... ;^) 1 Quote Link to comment Share on other sites More sharing options...
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