| Electronics > Projects, Designs, and Technical Stuff |
| Tube amp questions |
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| T3sl4co1l:
--- Quote from: spec on November 05, 2018, 05:21:02 pm ---If you are interested in the off-line switch-mode PSU approach, I can post a schematic of one of the designs I did a few months ago, which may give you a few ideas. --- End quote --- I'm a bit interested (maybe put it in another thread) -- does that come with winding details of the transformer, and EMC test results? Theory says (and backed up by my own measurements) that high voltage outputs are that much harder to pull off cleanly than low voltage (where you only have the primary's voltage and ringing to deal with). Tim |
| sahko123:
I would have used kt88s but that would have involved buying them. the 6550s where used for 5 euro 12 of them so I thought why not and they were shown to me to be all working so I couldnt let an opportunity like this pass. (Plus they look cool as hell) as for the Offline switch mode psu im not even sure where to start im not sure what they really are. I understand what switch mode supplies are but are hese ones specifically for powering vacuum tube circuits or other high voltage dc electronics? |
| chris_leyson:
RS Components sell a good range of OEP audio transformers everything from a few watts up to 25W, the larger transformers also have 20% taps for ultra linear operation. I breadboarded a single ended 3W amp using an OEP N35A002F and a 6BW6 with a 25% ultra linear tap, I don't know what's happened to it and I didn't get around to making any distortion measurements. Never mind, I've found another N35A002F so I will probably have another go at it, single ended or push pull. In push pull I can drive twice as many volts into the windings then I can push the core close to saturation. It's something that Peavey did with some of their amps, not only do you have valve sound but you got B/H loop sound as well. |
| Gyro:
--- Quote from: sahko123 on November 05, 2018, 06:11:32 pm ---I would have used kt88s but that would have involved buying them. the 6550s where used for 5 euro 12 of them so I thought why not and they were shown to me to be all working so I couldnt let an opportunity like this pass. (Plus they look cool as hell) as for the Offline switch mode psu im not even sure where to start im not sure what they really are. I understand what switch mode supplies are but are hese ones specifically for powering vacuum tube circuits or other high voltage dc electronics? --- End quote --- These days the economical alternatives are Soviet NOS GU50s, they look even cooler once relieved of their hot-swap (really!) knobs and lids. The only downside is 12.6V heaters (but half the current). Built like (for) tanks with hard glass envelopes and 4 getters! Strangely, once de-lidded, they look much more modern than the more recently designed KT88. - see attached (before and after). P.S. It's wise to cook them for a while to mop up stray gasses from cold storage before applying HT. |
| sahko123:
they do look really cool but I enjoy the smooth tops of the 6550s and nos tubes wont be around forever |
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