AOpen Debuts The Funniest Motherboard Ever

Anonymous Coward X-11 writes "Has AOpen gone flipping nuts by putting vacuum tubes on its motherboards? AX4B-533Tube No, it's not replacing logic ICs with discrete components. The tubes are part of the on board audio. Not sure if they are serious about this. April 1 was two months ago." As an owner of a tube headphone amplifier I applaud AOpen's move to accomodate the high-end audio enthusiast, while simultaneous wondering about the ability of a switched psu to properly drive a tube amplification stage cleanly. There's no way this is for real, right? Right? Here's a link that seems to work pretty well. And this looks pretty, well, real. Update: /. reader Jedi1USA noted that HardOCP has more pics of the board.

Comments

Why your dad says that...

[fmaxwell]

Tubes tend to produce even-order harmonics when they distort. Transistors (except MOSFETS -- others?) produce odd-order harmonics. Of the two, odd-order harmonics are much more annoying from a psycho-acoustic standpoint and lead to what many describe as a "harsh" sound. Tubes also have the advantage of not clipping hard (producing a DC output) because they have to run through transformers to drive speakers and, as we all know, transformers don't pass DC.

That's a gross oversimplification that leaves out much that I know, some that I think I know but don't really, and stuff other people actually know that I don't know at all. But that's the gist of it.

Is it of any use on a motherboard? Sure. It's great gimmick to sell to idiots. So how do they get stereo out of a single tube? It looks too small to be the two-tubes-in-one variety.

Re:They're all harmonics!

[mesocyclone]

Errr.... harmonics at clipping are all fun and that, but only if you have one sine wave in your amplifier. With real music, you have lots of signal in there. Then, any kind of nonlinearity, whether tube or solid state, will produce intermodulation which consists of sum and difference frequencies. Intermod is infinitely annoying and the real problem with distortion in amplifiers.

The math of this is simple - and applies to RF as well as AF. Take two of the signals in the systemm and approximate them for as sin waves. The nonlinearity can be modeled as a power series, so you have terms of the form:

f(a,b) = A*(a + b) + B*(a + b)^2 + C*(a + b)^3...

Substitute

a=sin(w1*t+phi)
b=sin(w2*t)

And do the trig and you can see that you end up with all sorts of neat frequencies such as

w1-w2, 2*w1-w2, etc.

Now, instead of f(a,b), imagine f(a,b,c,d,e,f,g...)_ and you can see the mess that intermodulation makes. It basically mixes (in the frequency domain) all of the signals AND all of their harmonics in all possible combinations!

Tube amplifiers *do* sound different because their distortion curves are different than solid state amps. Why audio "purists" prefer one distortion curve to another is what I don't understand. What I want is minimal distortion overall!

But then, audiophiles also buy gigantic cables because they imagine that their speakers will sound better attached to them... etc.

Technical note: The coefficients on the various terms of the power series tend to go down with the order of the term. And, some configurations approximately cancel out all odd or even terms.