CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => DIY => Topic started by: maverickronin on September 23, 2012, 12:30:45 AM
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I've been thinking about doing this for a while now, just for fun and possibly to learn something too. With those being the primary goals I'd like to do it on the cheap and hopefully still make something that sounds decent.
Is there anywhere to get decent quality power transformers and tube sockets without breaking the bank? I've got no idea where to start with tube sockets besides buying from random ebay sellers (who mostly seem to based in China) with good feedback and hoping for the best. For the power transformers, is there a better budget option than Hammond?
Also, while I have been reading up a bit on the theory behind tubes I don't know much at all about what's actually available on the market and for how much. Since output transformers probably would break the bank I'll probably have to go OTL. Right now I'm thinking something like paralleled cathode followers in hopes of a low-ish z-out but I don't even know how I should start looking for output tubes short of grabbing random data sheets and compiling all the relevant parameters into a spreadsheet or something.
Anyone got any ideas or am I asking too much?
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the CMC teflon tube sockets are usually pretty good.
I've no idea about the circuit part, but this project sounds like a lot of fun. Enjoy!
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The teflon is a bit pricey.
Plus if I mess something up and the socket gets too hot the teflon will out-gas some pretty nasty VOCs that will kill my pet bird pretty much instantly.
I've been looking for ceramic ones since they won't have that issue.
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here's some free reading - start with the "triode gain stage": http://www.valvewizard.co.uk/ (http://www.valvewizard.co.uk/)
another is Broskie's TubeCAD: http://www.tubecad.com/ (http://www.tubecad.com/)
Doug also has a lot of great stuff: http://www.ecpaudio.com/diy.shtml (http://www.ecpaudio.com/diy.shtml)
Morgan Jones is generally considered to be "must reading", but focuses mostly on output TX designs. for your purposes: http://search.barnesandnoble.com/Valve-Amplifiers-Morgan-Jones/e/9780750656948?sourceid=Q000000630&cm_mmc=Google%20Product%20Search-_-Q000000630-_-Valve-Amplifiers-Morgan-Jones-_-9780750656948&sourceid=Q000000633&cm_mmc=GooglePLA-_-Textbook-_-Q000000633-_-9780750656948&cm_mmca2=pla (http://search.barnesandnoble.com/Valve-Amplifiers-Morgan-Jones/e/9780750656948?sourceid=Q000000630&cm_mmc=Google%20Product%20Search-_-Q000000630-_-Valve-Amplifiers-Morgan-Jones-_-9780750656948&sourceid=Q000000633&cm_mmc=GooglePLA-_-Textbook-_-Q000000633-_-9780750656948&cm_mmca2=pla)
as far as tube sockets go, i like the Belton Micalex from TubeDepot.
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Thanks for the links.
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I was thinking of getting a Bottlehead Crack and messing about before starting from scratch. Tyll had a nice article on it recently. $279 gets you all in I believe. I'm at the point in my life where it's not just bottom line costs but calculating my time as an opportunity cost as part of the whole equation.
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+1 for micalex sockets, been using them too.You can find them slightly cheaper here (http://www.tubesandmore.com/search/node/Micalex).
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I was thinking of getting a Bottlehead Crack and messing about before starting from scratch. Tyll had a nice article on it recently. $279 gets you all in I believe. I'm at the point in my life where it's not just bottom line costs but calculating my time as an opportunity cost as part of the whole equation.
The instructions are simultaneously wonderful and awful. I put it together almost perfectly (electrically at least...) and didn't learn a damn thing.
+1 for micalex sockets, been using them too.You can find them slightly cheaper here (http://www.tubesandmore.com/search/node/Micalex).
Cool. Sounds like a good bet then.
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Sounds like a lot of fun, maverick. I'd love to learn more about amp design when I get some time to devote to intellectual pursuits. Please keep us posted (and feel free to post about it in the diary). I'd be very keen on tracking your progress and maybe learning things vicariously as you go along.
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Sounds like a lot of fun, maverick. I'd love to learn more about amp design when I get some time to devote to intellectual pursuits. Please keep us posted (and feel free to post about it in the diary). I'd be very keen on tracking your progress and maybe learning things vicariously as you go along.
I think I'm just going to get a bunch of semi-random parts and start experimenting with them in some kind of modular/prototyping sort of way and see if I come up with anything interesting or useful.
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thought I might be able to dig out a cool tutorial I had for getting started with tubes - sadly it has been lost in all the pc transfers I have had over the years but I will keep looking for it. Tubecad is one way to try and understand design and parts choice but sometimes Broskie gets lost in his own thoughts. Pete Millet has an incredible archive of old books on tube and design. Headwize has a few tutorial driven projects too.
I was going to suggest a kit too but as you have built the crack and not gained the sort of experience that you were hoping for, it really comes down to experimentation.
I think the important thing would be to read about different tubes of design, WCF, SRPP etc and then decide what you want to play with
for your experimentation, I would recommend these sockets - not good for the finished amp but it will allow you to breadboard easily.
(http://www.parts-express.com/images/products/large/075-166_l.jpg)
they can be found at many places but a quick google search found the one above at PE http://www.parts-express.com/pe/showdetl.cfm?Partnumber=075-166&utm_source=googleps
AC wrote this cool paper on WCF for headphones - makes for good reading.
http://www.cavalliaudio.com/diy/docs/WCFOptimization.pdf
If you have an idea of stuff you might need, I am happy to raid my parts box , you could probably build a dozen amps from the bits lying about.
..dB
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The Crack's instructions are pretty much just "solder part A to terminal 3" an so on. There's no schematic (presumably because they're worried about someone 'stealing' the design) and it doesn't really tell you what any of the parts are there for or what they do.
I was already planing to make my own version of that kind of socket you pictured by attaching a normal socket to turret board or something and running small jumper wires to some terminals. Then I can disassemble them later if I need to.
As for parts, I don't have much of anything yet. I want to keep the Crack in one piece to either sell or mod later if I learn something interesting from this messing around. The only potentially useful loose parts I have are a bunch of 250V resistors, a bag of random diodes that might have something useful, and several different tubes from the 12AU7, 6922, and 6080 families. I was thinking that I should just get the power supplies I need to run those tubes along with an assortment of resistors and caps to string them all together and then just try different stuff.
Thanks for the WCF link. It looks interesting.
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http://www.edcorusa.com/
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OOOh , when did they do this? I was always tempted by the jonokuchi
Based on the tubes ( 6922 ) , you might be good stating off with something like the Morgan Jones take on the Ear max
http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=cmoy5_prj.htm
..dB
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http://www.edcorusa.com/
Sweet! Just what I needed (http://www.edcorusa.com/p/831/tbpwr-mv2-120). Thank you.
Based on the tubes ( 6922 ) , you might be good stating off with something like the Morgan Jones take on the Ear max
http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=cmoy5_prj.htm
Yeah that was something I was looking at. I'm probably going to start with just a single triode gain stage though. It won't really do anything useful but I want to play around with something simple until I get the hang of all the parameters.
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still can't find that dern pdf but this looks handy http://www.guitarstudio.tv/documents/Designing-V-T-Amplifiers.pdf
Doug gives a little tutorial on calculating triode current on his MEHA project pages too ( ecp audio - posted above )
..dB
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Mav,
i don't know the schematic for the Crack, but it strikes me as a great learning tool to explore amplifier design and why the designers made the selections and choices they did. reverse engineer it. you're going to need to be adept at reading tube data sheets and drawing load lines. Broskie has software as well.
i really think you would like Morgan Jones - he offers very sensible, logical reasoning.
here's another link i forgot to mention: http://jacquesricher.com/NEETS/ (http://jacquesricher.com/NEETS/)
headbang
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Mav,
i don't know the schematic for the Crack, but it strikes me as a great learning tool to explore amplifier design and why the designers made the selections and choices they did. reverse engineer it. you're going to need to be adept at reading tube data sheets and drawing load lines. Broskie has software as well.
i really think you would like Morgan Jones - he offers very sensible, logical reasoning.
here's another link i forgot to mention: http://jacquesricher.com/NEETS/ (http://jacquesricher.com/NEETS/)
headbang
I haven't checked for sure yet but after doing some reading I think I've mostly figured out the Crack. It's a little cramped, and the sockets aren't the best quality so I don't want to mess around with it much until I at least get some better sockets and maybe some more spare parts. I'll probably end up building my own copy from scratch to make sure I understand it.
Right now I'm mostly making a list of parts I'd need and another list of reference material.
Thanks for that link. Looks interesting.
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So rather hilariously I've noticed that my Bottlehead Crack actually makes my PFE232 more neutral. Compare the FR and impedance plots (http://www.innerfidelity.com/images/AudeoPFE232.pdf) and add ~120-ish Zout. I noticed that a while ago but never got around to trying it.
OTOH it kinda defeats the whole point of them. I like that they sound natural at really low volumes so I can listen all day long w/o ruining my hearing. Also, the Crack really gets cranky like where they dip down to 15 ohms at ~9k and it makes maracas and cymbals sound like static. The rest of the spectrum isn't that bad, though I'd rather lay off the syrup and stick with my O2 or UHA-4.
They just don't look as impressive on my desk though...