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Ask Slashdot: How Do You Build Your Own Vacuum Tubes?
Could you beat wireless headphones by creating your own DIY home audio system? Two weeks ago one Slashdot commenter argued, "to have good audio that is truly yours and something to be proud of, you need to make your own vacuum tube amplifier and then use it to power real electrostatic headphones over a wire." And now long-time Slashdot reader mallyn is stepping up to the challenge:
I want to try to make my own vacuum tubes. Is there anyone here who has tried DIY vacuum tubes (or valves, to you Europeans)? I need help getting started -- how to put together the vacuum plumbing system; how to make a glass lathe; what metals to use for the elements (grid, plate, etc). If this is not the correct forum, can anyone please gently shove me into the correct direction? It needs to be online as my physical location (Bellingham, Washington) is too far away from the university labs where this type of work is likely to be done.
Slashdot's covered the "tubes vs. transistors" debate before, but has anyone actually tried to homebrew their own? Leave your best answers in the comments. How do you build your own vacuum tubes?
Slashdot's covered the "tubes vs. transistors" debate before, but has anyone actually tried to homebrew their own? Leave your best answers in the comments. How do you build your own vacuum tubes?
Here's a good one with links to more: http://hackaday.com/2016/05/04...
"Freedom in the USA is not the ability to do what you want. It is the ability to stop others from doing what THEY want"
You don't need vacuum tubes. That's such a horrible audio myth. They glow in the dark and look nice. Aside from that, they produce more distortion, more noise, use more power, are more fragile, and have shorter lifetimes than solid state electronics. They do not sound better, given $X spent on whatever, presuming some reasonable amount of tech is returned per dollar.
OTOH, if you just want to make vacuum tubes because.... you want to make vacuum tunes... have at it :)
I've fallen off your lawn, and I can't get up.
Okay, we need to discuss classic amplification (IOW, not digital) and tube vs. transistor distortion. Applies to all audio reproduction systems - receivers, preamps, amps, headphone amps.
When run entirely in their linear range, which is to say, in class A amplification, where very expensive and/or high end analog musical system designs sometimes run, analog devices, be they tubes, fets or bipolar transistors, all follow the input signal faithfully, plus or minus total system noise and phase shifts -- no "warmth" or other characteristics are inherent in even a half-decent design, unless you add it yourself with tone controls or the like. *NONE*. For the record, tubes make the most noise, bipolar transistors next, various field effect transistor types the least. Analog integrated circuits tend to use bipolars and/or FETs; look the specific IC up to see, there's no telling otherwise.
So what you want, ideally, is the very minimum of distortion, noise, and as close to perfect signal reproduction as you can get. What goes in equals, as closely as possible, what comes out. But class A is an expensive and power-hungry way to do anything. So most reasonably priced tube and transistor linear amplifiers tend to run in class AB, which uses two devices or sets of devices at the high levek output, where one set amplifies the negative excursions of the signal, the other the positive set. The idea is that the devices are slightly on all the time, and when they begin to amplify their part of the signal, there won't be much distortion from moving into the linear part of their amplification curve from the non-linear, off, part, because the device isn't switching from off to on, it was already on. This works really well, and some very high end tube and transistor equipment works this way. Uses a little extra power, but it's a great compromise.
So what's different in a useful and interesting way between tubes and transistors? Well, when a tube is pushed into its nonlinear range, the gain transfer curve bends over comparatively smoothly so that what would be a sharply clipped (squared off) signal in a device like a bipolar transistor, turns first into a compressed signal, and even later down the curve, begins to evidence harmonic and other distortion that somewhat resembles that produce by hard clipping, but has, because of that still-somewhat-gentle curve, an entirely different set of dominant harmonics as compared to, for instance, a bipolar transistor at or near saturation. So the distortion, when the system is run so hard it distorts, sounds quite different.
That characteristic is why (knowledgeable) musicians who use distortion as a tonal tool often choose tubes; specifically because these musicians *do* run the tubes out of the linear area of the transfer curve, and the result is interesting -- and often pleasing. When the distortion is the result of a transfer curve that abruptly goes from highly linear to highly nonlinear, as is the case with bipolar devices, the result is most unpleasant. Edgy. Sharp. Dissonant. It isn't very often that such a thing is well received in a musical performance.
However, this choice does not *ever* hold true for a musical reproduction system based on tubes that isn't running in a range that will distort the music. You'd have to turn it up so far that one or more elements of the preamp or power amp is pushed past the linear part of its transfer curve, and then all of the music distorts -- and that's not a "warm" sound, that's a "hey, your system sounds awful, turn that thing down before I puke" sound.
So, for example, if I get out my Les Paul or my Strat and plug it into a tube amp and turn that bizatch up, I'm doing so because the amp's distortion is going to very significantly color the reproduction of what I play. I'm going to adjust the amp specifically so I *get* distortion. It'll sound fabulous. I'll get feedback, there will be awesome weirdnesses when I hit harmonics on my strings, pick and fretting artifacts will sound very different,
I've fallen off your lawn, and I can't get up.
Howdy all, I'm a scientific glassblower (25 years now), and I make my own tubes. I'm at www.incandescentsculpture.com; not much tube info there yet -been a few years in beta mode on them, but some other high-vacuum delights are to be seen. (My handmade incandescent bulbs, my Tesla wireless brush bulbs, the 'fuxie' tube....) Even the production of a simple, low-mu triode is non-trivial; the requisite equipment and knowledge take years to acquire, and a page long essay to even enumerate. OP, I'd be glad to help; perhaps we can compose a FAQ and parts list for kindred spirits.