DefQon Posted May 16, 2014 Report Share Posted May 16, 2014 Building amps is fun. Getting the case/enclosure work is not. Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted May 16, 2014 Report Share Posted May 16, 2014 Building amps is fun. Getting the case/enclosure work is not. I really enjoy the case and design aspect. 1 Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 16, 2014 Report Share Posted May 16, 2014 Ditto but sometimes it is just a pain. Quote Link to comment Share on other sites More sharing options...
eggil Posted May 17, 2014 Report Share Posted May 17, 2014 (edited) I have never used tubes before, so I am a complete novice when it comes to filaments. Thank you Kevin and Victor for putting up with my dense lack of knowledge... Here are the transformers and wiring I am using for my build. The transformers are all Triad Magnetics and their product # is in the PDF file. Feel free to berate me if I screwed up https://www.dropbox.com/s/75av9kajl6zin6u/Megatron%20tube%20transformers.pdf Edited May 17, 2014 by eggil Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 17, 2014 Report Share Posted May 17, 2014 That looks good. I still don't know why we made the front end filaments 6.3V though. They really should have been 12.6V or even 25V. Hell a LM7824 with a diode on the ground pin would be perfect for that. Quote Link to comment Share on other sites More sharing options...
SoupRKnowva Posted May 17, 2014 Report Share Posted May 17, 2014 That looks good. I still don't know why we made the front end filaments 6.3V though. They really should have been 12.6V or even 25V. Hell a LM7824 with a diode on the ground pin would be perfect for that. What makes using 12 or 25 volts better than the current 6? And would it be possible to use the current boards at those filament supply voltages? Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 17, 2014 Report Share Posted May 17, 2014 Higher voltage means less current so easier to power using regulated DC. No possible to do on the current boards without cutting some traces. Quote Link to comment Share on other sites More sharing options...
eggil Posted June 6, 2014 Report Share Posted June 6, 2014 (edited) I was thinking on using these Amphenol connectors for the umbilical cord: MS3106F28-12S http://www.mouser.com/Search/ProductDetail.aspx?R=MS3106F28-12Svirtualkey65400000virtualkey654-MS3106F28-12S and MS3102A28-12P http://www.mouser.com/Search/ProductDetail.aspx?R=MS3102A28-12Pvirtualkey65400000virtualkey654-MS3102A28-12P Edited June 6, 2014 by eggil Quote Link to comment Share on other sites More sharing options...
nopants Posted June 6, 2014 Report Share Posted June 6, 2014 There are some vintage? military connectors listed on ebay that would fit the bill, I can't remember in which thread they appeared. Definitely less than 74 a pop Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 6, 2014 Author Report Share Posted June 6, 2014 you only need 6 pins which are a lot cheaper Quote Link to comment Share on other sites More sharing options...
eggil Posted June 7, 2014 Report Share Posted June 7, 2014 You mean you are installing all the filament transformers in the amplifier, not in the power supply box? Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 7, 2014 Report Share Posted June 7, 2014 The filament transformer for the CCS tubes have to be close to the amplifier board. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 7, 2014 Author Report Share Posted June 7, 2014 actually you need 8 pins. the ccs transformers absolutely have to be inside the amp box, and you might as well put the other one there too. Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 7, 2014 Report Share Posted June 7, 2014 I would also run the raw mains on a separate umbilical. For safety and all that something like the Neutrik Powerkon would be perfect. Quote Link to comment Share on other sites More sharing options...
eggil Posted June 7, 2014 Report Share Posted June 7, 2014 (edited) OK, then: 1- the Neutrik Powerkon for the raw mains going to the filament transformers. 2- the 8 pin Amphenol for the main transformer. Edited June 7, 2014 by eggil Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 7, 2014 Report Share Posted June 7, 2014 I'll be doing something like that. I'll probably rewire the front end filaments to run on 25VDC too. Quote Link to comment Share on other sites More sharing options...
eggil Posted June 24, 2014 Report Share Posted June 24, 2014 (edited) Here is first power up. All LED's turned on. The 2 closest to the tubes not as bright as the other 2. Tubes got warm but did not see any glow. Where is the glow?? Got cold feet after a couple of minutes and turned it off. Thumping heart rate @ 140 per minute. Nothing exploded. Edited June 24, 2014 by eggil Quote Link to comment Share on other sites More sharing options...
chinsettawong Posted June 24, 2014 Report Share Posted June 24, 2014 Nice going. Quote Link to comment Share on other sites More sharing options...
eggil Posted June 24, 2014 Report Share Posted June 24, 2014 (edited) Oh my goodness! They are so beautiful! I can now see why people like tubes! My wife is in Finland with my camera. iPhone pics. Edited June 28, 2014 by eggil 2 Quote Link to comment Share on other sites More sharing options...
livewire Posted June 24, 2014 Report Share Posted June 24, 2014 Noice! Quote Link to comment Share on other sites More sharing options...
Victor Chew Posted June 24, 2014 Report Share Posted June 24, 2014 Congratulations on the successful power up. I am far behind you. Just got my casings and my amp board isn't even populated yet. Quote Link to comment Share on other sites More sharing options...
eggil Posted June 27, 2014 Report Share Posted June 27, 2014 Almost to the point I can hear music. Perhaps today. The casing though.... that will take time Quote Link to comment Share on other sites More sharing options...
eggil Posted June 28, 2014 Report Share Posted June 28, 2014 DC Offset is staying around 4V for both channels. I am concerned however that the heat sinks for the 8N80C's are a toasty 80 degrees Celsius. I know there is more current than the KGSSHV because the 3904's are not installed, but isn't this a bit too much? My KGSSHV's were in the 60 degrees range. Quote Link to comment Share on other sites More sharing options...
eggil Posted June 28, 2014 Report Share Posted June 28, 2014 (edited) And another Megatron comes to life! Bach sounds glorious Many thanks to Kevin for this wonderful design, to Birgir for preventing a major disaster with the PSU, and to RiStar and Victor for their much needed assistance. Edited June 28, 2014 by eggil Quote Link to comment Share on other sites More sharing options...
nopants Posted June 28, 2014 Report Share Posted June 28, 2014 I'm considering tricking mine out with another hv supply for the 300v line, anyone know of appropriate low power (ie reasonably sized) transformer? how does the srd generate bias in that small package? Quote Link to comment Share on other sites More sharing options...
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