Electronic Design Mag discovers High End Audio!

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Except it is not adding harmonics unless the source is a single tone. The only device that could truly "add harmonics" would be a pretty sophisticated digital device that analysed a waveform, broke it down into its constituent source waveforms, tweaked the harmonics of each individual source, then re-synthesised the output. (It couldn't do much with non-harmonic/noise-like sources!)

Amplifier 'harmonic' distortion is primarily non-linearity that doesn't really care about fundamentals or harmonics. The non-linearity smears the individual source waveforms together, so that they can no longer be separated cleanly (by the ear), and one source in the mix influences another. Intermodulation distortion is spoken about as though it is a separate property distinct from harmonic distortion, but only a computerised gizmo could give you THD without IMD.

Maybe this wonderful tube-like quality sounds OK on already 'smokey' recordings - Nina Simone, jazz and stuff like that seems popular around these parts - but I wouldn't want it on a cool, spare, modern orchestral piece where I would want to hear each instrument as unaffected by the others as possible.

It was a tube stage with control of distortions produced by vacuum tube triode stage. The purpose was to experiment, if it is true that specific tube distortions add "tube warmness" to the sound. The answer is no: adding distortions do not add "tube sound", but add intermodulation distortions instead.

Nothing like "wonderful tube-like quality". That means, it is naked myth about "specific tube distortions" that are preferred by some "tube sound enthusiasts".

But a tube amp with 0.01% THD that I designed, and built as a prototype, indeed sounds like a tube amp: soft, warm, transparent. My conclusion was, using of vacuum tubes allows to avoid "transistor harshness".

Further experiments proved that indeed further minimization of distortions increases softness and transparency, up to the moment when sounds reproduced start being confused by subjective mind with real sounds. But such reduction of distortions has nothing to do with further reduction of THD by deeper overall feedback. It is mostly assistance to active devices to work in more stable regimes, with decreased variations of their parameters. Like, load of vacuum triodes on higher dynamic resistance, bootstrap of FET followeers, paralleling of BJTs to minimize effect of beta droop, design of wideband stages, and so on.

And one more surprise: I've found that smoothness of transfer function means lower distortions than it's linearity. I.e. attempts to improve quality of an amp with smooth transfer function by decreasing of distortions applying feedback makes transfer function more linear but less smooth. It decreases THD, but increases audible distortions.
 
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It's interesting that J. Gordon Holt, who was one of the early and most influential proponents of "tube sound," described it as bright and forward, not soft and warm.

People of different thinking habits use different language. For example, if you use visual language with kinestetic you induce trance state instead of understanding. And vice verse. :)
Professional hypno-therapists use this well. ;)
 
Nothing like "wonderful tube-like quality". That means, it is naked myth about "specific tube distortions" that are preferred by some "tube sound enthusiasts".

Ok your hybrid is the best for you, since it is relative, but I more like clarity in amplifier.
I have question, if you really do any good experiments.
The question about tubes are many, but i just asking one, here: "why tubes always has tonal characters?" please explain its mechanism, and if you wish you may also explain what affected by this.;)
 
It's interesting that J. Gordon Holt, who was one of the early and most influential proponents of "tube sound," described it as bright and forward, not soft and warm.

But the low damping factor that usually accompanies tube amplifiers gives a 'warm' frequency response regardless of the type of device (tube or SS). Maybe if it is supplemented with sufficient distortion, it can be brightened up enough to compensate.
 
The question about tubes are many, but i just asking one, here: "why tubes always has tonal characters?" please explain its mechanism, and if you wish you may also explain what affected by this.;)

I've explained many times: absence of Kirk and Early effects, no inertia of charge carriers, and so on. Simple geometry, simple laws that are close to properties of mechanical media that transfers, absorbs, reflects sounds. We don't hear such alterations as distortions, while distortions specific to electronic devices are well audible as artificial distortions.

If you want to argue, please find some other opponent. I just shared my own experience and my own conclusions, that are different from yours, and of course lead to different end results.
 
There is not enough 'definition' here of a specific tube amplifier to be SPECIFIC how it sounds. For example, a Marantz 9 in triode will sound smooth, and a Mac 75 might sound 'bright and forward, yet a Mac 350 might sound almost as smooth as the Marantz 9 in triode, or more like a Marantz 9 in 'Ultralinear' mode.
 
But the low damping factor that usually accompanies tube amplifiers gives a 'warm' frequency response regardless of the type of device (tube or SS). Maybe if it is supplemented with sufficient distortion, it can be brightened up enough to compensate.

Once again: it is not about "Usual" damping factor. My Pyramids have HIGH damping factor, but despite of LOW THD, WIDE BANDWIDTH, and HIGH DAMPING FACTOR they don't sound like transistor amps. One Pyramid during BAF 2008 festival was used to listen to Hi-fi speakers with crossovers, and nobody heard anything "transistor" in it's sound. Jan Didden when published it's picture called it "Sweet sound of Anatoliy's Russian glassware". SY saw distortion pattern of the amp on the screen of his computer, but he did not see anythging that can "add sweetness". 0.01% of 2'nd order harmonic can't add any "sweetness" to the sound, right? What can add "sweetness", absence of higher order harmonics, and LOWER distortions the LOWER is loudness, and absence of audible phase intermodulation.


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Edit: damping factor affects frequency response ON THE LOWEST frequency that the speaker effectively reproduces. If it's main resonant frequency is say 63 Hz I don't understand how such boomy resonance can add warmness. It is some kind of a miracle you are talking about. :D

When damping factor is more tan 10, be it 100 or 10,000 I doubt you can hear any difference of damping of main speaker's resonance. But you definitely can hear nasty harsh clipping of the later amp when it is overdriven, because the amp with 10,000 damping factor must have such feedback that causes very sharp clipping.
 
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There is not enough 'definition' here of a specific tube amplifier to be SPECIFIC how it sounds.
I hear you, John. I don't really know what "tube sound" is. It's a constant cliché, but few tube amps I've heard have a "tube sound", whatever that is.

An important moment for me was many years ago in Paris at a tube expo. Jean Hiraga was there with his "Tube Museum". He had set up a system to let us hear many vintage tube amps from his collection. Same CD player, same tracks, same speakers, only the amps were swapped. Dynaco, Marantz, Scott, Fisher, MacIntosh and many others I don't remember.

They all sounded pretty much alike (except one with a bad cap), there were some differences, but nothing dramatic. Expect one. The MacIntosh. I don't remember the model, but it was lush, warm, sweet, big and pleasant. Like a sunset thru rose colored glasses. Now THAT was "tube sound"! A lot of fun and made me understand in an instant how Mac sold so many amps. It was a great sound, but not anything I'd ever buy - far too colored. Many in the audience agreed. The Mac was a lot of fun and very pleasant to hear, but the the more neutral amps would be preferred in the long run.

Since then I've heard many tube amps that sounded a lot like solid state, I doubt most folks would peg them as tube. And I've heard a number of transistor amps that were warm and forward. Fooled me into thinking they were tube.

Bottom line. When I actually listen to real tube amps, I find it hard to hear any distinct, common signature. I find the find cliché doesn't hold.
 
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