Hopefully A Painlessly Way To Get Into Experimenting With Tubes

Discussion in 'Shock Brother's DIY Amps' started by printer2, Feb 19, 2020.

  1. printer2

    printer2 Poster Extraordinaire

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    I have been thinking about for a while, I am building another building board. A 12" deep piece of shelving, some aluminum foil over it as a ground plane, a press-board back from an organ. A hole drilled into the press-board and a tinned wire running the length of it, sandwiched together with some screws. The wire will go to a ground point and the foil will act as a shield reducing noise.

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    An assortment of switching power supplies at the back mainly 12V although I have other voltages and will discuss them at a later date. Will have a pair of octal sockets, pair of seven pin and four nine pin sockets. Along the left I will have some terminal blocks to make it easier to hook up the power to, not necessarily the ones shown, I think I have some others kicking around here, just depends if I will find them in time. In the front, a plate for input and pots. To the right of it is a stepdown converter hooked to a 6V pentode, will rewire it. Then the tiny board, a single voltage to +/- 24V converter, then a high voltage switcher to put out up to 400V if you can believe the ad.

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    Done enough today, will do some soldering tomorrow and probably screw things down. Then the first experiment, see if the +/- 24V will be enough voltage to put across a tube or two. If so, build a preamp to go into a class D amp. I thought up this project to get a tube to run in a lower voltage circuit for the pedal crowd or anyone that wants to start off without worying about high voltage.
     
  2. tweedy_woodpecker

    tweedy_woodpecker TDPRI Member

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    Great. Looks like an interesting project...
     
  3. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Great idea for a guy with as many ideas as you have - I like it!
     
  4. printer2

    printer2 Poster Extraordinaire

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    Just never had the time to mess around much, too many other priorities, retired now. So I should get to try out some of them. But my real aim is to see if this would be a feasible way for others to go down the rabbit hole. I want to see the limitations of the high voltage module, yes there might be smoke. But getting ahead of myself. First the low voltage tube idea. A 12AX7 sucks on low voltage in my mind (sorry Valvecaster), a 12AU7 should sound better at 48V, I think a 12AY7 might just squeeze enough out of that voltage, only one way to find out. The tube kits for sweetening up your stereo (not my cup of tea) has seen a few people try the 6AK5 (Chinese 6J1) although they only tried it in triode mode. I would like to see it as a pentode.

    I have been looking at the tubes I have and what the pin-outs are. Shame they are all over the place, little consistency. I started wiring some of the sockets with colors that hopefully makes some sense to me, really just going to have to make a lookup table for each tube type. I'll wire up what I need to try out this first project and do the other socks as needed. I am splitting my time between this and some guitar building, bouncing back and forth between them. And then there are the non-guitar related stuff I got going on. So this will be a slow burn kind of thread, when I feel guilty about one project being ignored I allocate some time to it.
     
    Mr Ridesglide likes this.
  5. FenderLover

    FenderLover Poster Extraordinaire

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    That looks like the same high voltage switcher I have on my bench right now. I've noticed that it wants a modest load in order for it to start regulating, so a triode amplifier stage may not provide enough of a load. Just be aware. You may need to waste power with a passive load just so that it starts regulating to hold up the output voltage.

    I'm using mine for a triode buffer pedal with paralleled triode stages, so the output current of my 12V supply is better than 4W. Just to spill the rest of the beans, it runs on 250V, and drives two outputs, one transformer isolated as a signal splitter.
     
  6. printer2

    printer2 Poster Extraordinaire

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    I have been debating on what to do first, want to use the +/- supply board to power a tube preamp, had some ideas but a thread in another forum had me moving virtual parts around to get a Long Tail Pair type of stage together. Being the curious type I wanted to know if I could cascade the stages with the use of a switch. Just a rough idea, part values will most likely have to change or disappear/show up. A late night idea.

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