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This is how I wired my pot. Don't forget to ground the metal pot casing too.
I just built one of these, found some of the 19j6's in my uncles collection of tubes and he let me have them. Such a nice little amp! Way more detailed and smooth than I expected. Once I get more time I'll have to read through the thread here a build another one with some 17EW8's or 12AU7's.
Show us some pics! I have a 12AU7 version which sounds absolutely wonderful. I like it better than my Hi-Performance Mini³. That's what I would like to have: a headphone amp with the the sound of my 12AU7 and the portability of the Mini³.
Thanks Beftus, that perfect, and it matches the pic of P. Millet! All my problems resolved!
You're welcome Antoine. Oh and now that your problems are resolved, please show us the amp when you finish it.
For my next 12AU7 I'm slowly gathering parts and assembling small building blocks. Here's the progress so far.
Caps are Elna RJH 470uF and Elna Silmic 470uF output caps with MKP1837 bypass caps. Interstage caps are MKP1837's too. Tube sockets with 1K grid stoppers. IRF510's with gate stoppers. Blue tube LED.
Well here are a couple crappy cell pix, just built it at a camp and will be staying here for a few weeks and I forgot my camera.....
I am really diggin this amp! Its much better than I expected. I can forsee this getting alot more use than planned
LOL. Great looking box!
Looks good Trower, I really like the look, its "Starving Student" for sure. How about a peek inside ? How much did you spend on the build?
Thanks, I really like the way the cigar box looks with tubes As far as seeing the inside, she's glued shut now.......plus it was a quick build that I didn't pretty up, so I would kinda be ashamed to show it
As far as cost, I got the sockets and tubes for free from my uncle who used to have an electronics repair shop for years, and alot of the parts I had lying around, so it kept the cost for parts to about 20 bux I would say. I'll post some better pictures of the next one I build....though that might not be until the fall when I have more time.
The idea of doing a P2P build of this scares me a little. The idea of troubleshooting a P2P build scares me a lot. Since the PCBs aren't available any more, I thought I might try doing a protoboard build using the Radio Shack 276-0150 that tangent's cmoy tutorial uses. The first step of my plan was to draw a board layout and post it here for comments; I was hoping to get some advice before I started, however.
Is this an entirely stupid idea?
Any recommendations for how to draw the layout (besides pen and paper)? The images on Tangent's site (160k pdf) are nice, although I don't think I need them to be so fancy. I was hoping Eagle would have some protoboard templates, but no luck.
Are there any parts of the layout were I'd need to allow extra space between components?
Better make sure you don't make any mistakes then... The Starving Student was my first P2P build. Just take your time and double check everything do. Measure every resistor prior to soldering it. Lay out all the parts needed in front of you, make sure you don't forget to add a single part.
I forgot to add two resistors, got 12.5 volts on the output, saw my mistake, added the last two resistors and then it worked.
Yeah, and don't mix up a 33k and a 390k...you'll end up with it sounding really quiet for a while...than a tube will go out...
1) No, not at all, but P2P would probably be a lot easier than coming up for a layout on protoboard IMO. There aren't that many parts in this build, and if you are clean about your wiring (making wires as short as possible) and don't just leave uninsulated leads sticking out all over the place you'll be fine. Troubleshooting P2P is no different than a protoboard - putting something on a board doesn't mean you won't make errors as to which resistor to use where, or what should be connected to what. A PCB fixes this because you can not vary from the design even if you tried (except putting parts in wrong places). A protoboard lets you do whatever you want and thus IMO is the same as P2P, just with a nice board holding everything together. The board might actually be harder because you have less freedom of placement.
2) I don't believe there are any programs that have any sort of protoboard design tools. If you want it to look nice you could use Illustrator, but that's just pen and paper on a screen.
3) Yes. The MOSFETs usually are mounted to heatsinks outside the case. Obviously the tubes don't go to the board. The LED resistor should have some space as it's putting out a lot of heat, if you choose to use LEDs.
So, in summary, don't be afraid of P2P. And either way you go, don't forget to use a star ground - hum has been known to be a problem.
Are the 12AU7 like these the cheapest tubes to use? What is the likely hood that within a year one of the tubes will fail? Would it be worth it to get 3 or 4 as spares since the tubes are $5 each and shipping is $8 no matter how many I get?
The terrible secret is that some 12AU7 tubes are among the most expensive of all tubes. At the very least, they are not among the "cheapest." Plentiful, but at the same time in high demand, they occupy something of a middle-level price range in the tube market. Of the variants available, the 5963 is probably the cheapest, but that still may not be cheap on the Starving Student scale. If you bought two tubes from the link you gave, you'd spend $18 for two tubes - that's $9 each, not what I would consider cheap. Better deals can be had from recognized tube vendors.
As for getting spares, I wouldn't worry about whether the tubes will fail. In the Starving Student, they are running at a much reduced plate voltage and will probably outlast the amp itself. Rather, if you are buying "pot-luck" ebay, as it were, the goal would be to get as many as you can so that you increase your odds of having a pair that are the better performing out of the group (tube quality is sometimes wildly variable) and that match each other.