bluefoxicy Posted April 1, 2008 Share Posted April 1, 2008 Let's say you have a spare combo amp chassis and you really, really hate the amp; but it has a nice 8 ohm speaker in it, enough room to pack in tubes and the OT and a full valve junior circuit easy (but what doesn't), and you have a spare 5.2k VJ V3 OT on hand from a Hammond upgrade. This might all work out well and good, but what about power? I ... THINK there's room for a power source, here's what I got.. Now, that 8 ohm speaker runs 2 watts, so the 5 watt EL84 output will of course be too much. I could always reduce the plate voltage, though that could adversely affect tone beyond a point. Not really sure what to do here. I think on two 9-Volts, 550mAh each (alkaline), 12W/18V == 2/3 of an amp, maybe an hour and a half for just that power tube? But the whole circuit needs 35W to run, so it's more like half an hour... I'm pretty sure I can get 4 9Vs in there if I really want to though, parallel, allowing more current draw; and use a small silicon DC-to-DC converter for filament and plate input voltages. Have to use more raw resistance and less voltage divide to ground (positive) to regulate power though, changes around R10 (remove) and R11 (increase) for example. Can totally remove C6, C7, C8, C9, and 12 probably due to no ripple. Replace R7 with an open and R6 with a short. That'll move a lot of the big components directly out of the circuit and leave lots of room. Any thoughts? Link to comment Share on other sites More sharing options...
m-theory Posted April 1, 2008 Share Posted April 1, 2008 Gut it and make it into a Ruby, or one of the modified variations. I don't know that it's going to be worth your effort to try to power a tube amp on 9v batteries, frankly. Assuming you ever can get it to work, it's not likely to be very impressive, and will undoubtedly burn through batteries faster than you could replace them. That's just my opnion, however, and I'm admittedly no expert on amps and current draw. You should pose this question on sewatt.com. It's entirely possible that somebody over there has already tried this, perhaps successfully. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 1, 2008 Author Share Posted April 1, 2008 Uh. Wow Didn't think anyone would actually take that seriously. Well, except maybe TWANG. Link to comment Share on other sites More sharing options...
m-theory Posted April 1, 2008 Share Posted April 1, 2008 Uh. Wow. As an April Fool's attempt, I've seen much better. Apparently, you haven't been around long enough to see some of the ideas bandied about. One guy even wanted to know what vocal mic to buy for his Vlv Jr....oh wait, that was you! This one is totally believable, and in fact, like I said before, it's probably been attempted before, and perhaps even successfully by someone. Link to comment Share on other sites More sharing options...
bluefoxicy Posted April 1, 2008 Author Share Posted April 1, 2008 Hah true. Keeping a VJ powered on a small array of rechargeable 9V batteries WOULD be a project; but miniaturizing it and ditching the power filter cans and the PT for pure DC voltage and silicon DC-to-DC converters is simple enough. Hell, a custom-fab'd plate Li+ battery could power it, maybe an inch thick version of the thing that powers my laptop? That's about the right dimensions. But by then you're talking about "I'm planning to market this" instead of "this is a hobby project" ne? Heh. You know I'm starting to realize how cool that would really be. @_@ Link to comment Share on other sites More sharing options...
m-theory Posted April 1, 2008 Share Posted April 1, 2008 It would be cool, but alas, probably not worth the effort! Link to comment Share on other sites More sharing options...
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