well Im a half tube head, I have two tube preamps, and will probably build another in the not too distant future🙂 I could see building another tube amp (last one was dissapointing) but good iron in this part of the world is hard to get.
The difference in sound quality is even more stark on real stereo recordings, of
acoustic music of course.
Going with tubes stopped me worrying, and off the upgrade thing, and back to music.
First a friend lent me two Radford stereo valve power amps, and the stereo pre.
Then through a series of swaps and actual gifts, I ended up with two rebuilt (upgraded and improved) LEAK Stereo 20's, and a classic four valve (4 twin triodes) preamp.
note that I was using a notably sweet sounding SS integrated by Luxman before that.
BSEGrin!!!
acoustic music of course.
Going with tubes stopped me worrying, and off the upgrade thing, and back to music.
First a friend lent me two Radford stereo valve power amps, and the stereo pre.
Then through a series of swaps and actual gifts, I ended up with two rebuilt (upgraded and improved) LEAK Stereo 20's, and a classic four valve (4 twin triodes) preamp.
note that I was using a notably sweet sounding SS integrated by Luxman before that.
BSEGrin!!!
I'm currently listening too Gregg-the-Geek's DynaMutt and am very pleased with it.
dave
Hey Tim, nice to see you stick your head up... was thinking of you recently when a discussion turned to statistics 🙂
dave
Distortion Characteristics
I can't vouch 100% for this, but my understanding is that the normal distortion characteristics of tubes vs. transistors has a lot to do with their popularity in sound reproduction amplifiers. The overload distortion characteristics is part of the picture, but even outside of overload, tubes alter the signal differently than transistors do. IIRC, transistors produce more odd-order harmonic distortion whereas tubes produce more even-order harmonic distortion. The even-order harmonic distortion is more pleasant to the ear than the odd-order harmonic distortion which makes tube amps more pleasant to listen to for many people.
I'm not sure there's much of an argument for one or the other being more or less linear than the other, and there are all kinds of arguments around negative feedback in the amplifier being detrimental to the sound (which you generally get lots of in solid state amps and may get less of - or none - in tube amps). Both solid-state and tube amps affect the signal going through, and the manner in which they distort the signal seems to have a lot to do with why one is felt to be more pleasant than the other.
Or at least, that is what I recall reading...
Lyle
I can't vouch 100% for this, but my understanding is that the normal distortion characteristics of tubes vs. transistors has a lot to do with their popularity in sound reproduction amplifiers. The overload distortion characteristics is part of the picture, but even outside of overload, tubes alter the signal differently than transistors do. IIRC, transistors produce more odd-order harmonic distortion whereas tubes produce more even-order harmonic distortion. The even-order harmonic distortion is more pleasant to the ear than the odd-order harmonic distortion which makes tube amps more pleasant to listen to for many people.
I'm not sure there's much of an argument for one or the other being more or less linear than the other, and there are all kinds of arguments around negative feedback in the amplifier being detrimental to the sound (which you generally get lots of in solid state amps and may get less of - or none - in tube amps). Both solid-state and tube amps affect the signal going through, and the manner in which they distort the signal seems to have a lot to do with why one is felt to be more pleasant than the other.
Or at least, that is what I recall reading...
Lyle
In their essence, electrons flow from negative to positive. Resistors, capacitors, inductors, xformers, and tubes. Tons of circuits. Easy to do point to point wiring when on picks up a few terminal strips.
For me, its just plane FUN.
Best from Tucson Arizona
Bob
For me, its just plane FUN.
Best from Tucson Arizona
Bob
How about a tubed deuterium arc lamp power supply?
Electronics Forum -> Tubed Deuterium Arc Lamp Power Supply
Electronics Forum -> Tubed Deuterium Arc Lamp Power Supply
The reason to use tubes is that due to their linearity, they more closely obey the rules of human hearing than transistors do. This is not to say that transistors can't also be made to work, but its a lot harder, here's why:
Choas Theory has shown that amplifiers with negative feedback are unstable non-linear dynamic systems when amplifying a constantly changing waveform. What we want in audio is something that is linear. Norman Crowhurst showed over 50 years ago that feedback creates a harmonic and inharmonic noise floor in any audio circuit. Our ears can hear about 20 db into a natural noise floor (BTW Choas Theory has something to say about that; amplifiers without feedback have a natural noise floor that is identical to the out-of-doors and for the same reasons). That is why we can extract spatial information even if the wind is blowing. However, our ears have trouble penetrating this harmonic/inharmonic noise floor that feedback creates so spatial information (and detail) below that threshold is lost.
Tests on human hearing done by General Electric during the 1960s shows that humans use the 5th, 7th and 9th harmonics of a sound to determine its loudness. Loop feedback enhances these harmonics- if only by 100ths of a percent, that is still enough to be audible according to GE, and is borne out by audiophile terms for the same: bright, brittle, hard, harsh, etc.
Tubes allow you to build audio circuits without feedback. So it is possible to build circuits that do not violate fundamental human hearing rules, like how we perceive loudness or how we perceive spatiality. You can do this with transistors too, but like I mentioned, its a lot harder.
Dr Herbert Melcher, a noted neuro-chemical scientist, has done tests with sound reproduction systems and has found that the brain knows when a stereo is trying fool it; the more the basic perceptual rules get violated by the sound reproduction system the more the sound processing moves from the limbic/emotional system to the cerebral cortex. Fascinating stuff.
Intuitively that makes a lot of sense. Where can i read more?
Is this much in the sense of the simple iterative (feedback) equation that generates a fractal like the Mandlebrot set? Or does it have less order?
dave
Aerodynamic theory says a Bumble Bee can't fly. 😀 The H/K Cit. 2 employs approx. 36 dB. of NFB in 3 nested loops. The design is unconditionally stable. Like aerodynamic theory, chaos theory must yield to empirical reality.
BTW, the "Duece" sounds VERY good.
BTW, the "Duece" sounds VERY good.
Nonlinear dynamics is applicable for nonlinear feedback systems. For linear feedback, as in audio amplifiers, Bode-Nyquist theory seems to work exactly as predicted. If someone has demonstrated that unconditionally stable amps are actually unstable, I'd love to see that demonstrated.
No way! I prefer metal, techno, and hard rock in general. For that, VTs are better. Once I had a tube amp up and running, it was like getting a whole new CD collection for free. There was so much more detail that you just could not hear through the Big Box, SS amp I was using before that.
One project I did includes variable gNFB. With that, easy listening, etc. seems to prefer turning up the gNFB, whereas hard rock really comes alive with less gNFB.
Although solid state gets a bum rap these days since there are so many examples out there that are a good deal worse than they ought to be. Still, I've done some SS designs that beat the daylights out of any Big Box system. I'll do more in the future. However, these designs don't get all the way there, and VT amps still sound better.
FWIW, the best sounding amp I've built is all sand. But, it is transformer coupled on the input (Lundahl amorphous) and the output (Cinemag nickel) and the circuit is basically a "tube" circuit except I can get away with 150 ohm OPTs. I generally prefer tubes to sand, but really what I prefer are good designs. 🙂
Do you have the references for this stuff? Particularly the Norman Crowhurst article and the theory on "out of doors" noise?
Iron costs money. You won't find that kind of design outside of boutique gear. Is a schematic of that design posted anywhere? I'm curious.
Ah... there's that chestnut about the bumblebee again. They found that the missing understanding had to do with the compression of air. This was discovered decades ago yet people still quote that. Not to be contrary but... I'm just saying.
My point was that when theory and reality conflict, the theory gets altered. The Michaelson/Morely experiment and Einstein's Special Relativity are a paradigm case.
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