Vacuum-tube amplifiers are not in the same class with techniques that are unlikely to have any perceptible influence on what you hear.

Among amplifiers that are not perfectly neutral, vacuum-tube amplifiers subjectively seem more pleasant.

Moreover, while an electronic audio amplifier made with modern components can be made perfectly neutral when terminated on a resistive load, i.e. it can reproduce any input signal without any changes except amplification at its output, once you connect loudspeakers at its output the amplifier-loudspeaker chain is no longer neutral, i.e. it no longer has a flat transfer function between the electrical input and the sound output and it is not at all clear which should be the output impedance of the amplifier as a function of frequency to ensure the least degradation of the sounds in comparison with the input signal.

So it may happen that a vacuum-tube amplifier - loudspeaker system has actually a better overall fidelity than a typical audio amplifier that was designed to demonstrate a much higher fidelity on a resistive load (because thus the transfer function is easy to measure and correct, unlike the complete transfer function to sounds).

In theory, one could make a modern amplifier reproduce any quirky behavior of vacuum tubes, e.g. a higher and frequency-variable impedance or certain kinds of distortions, but usually nobody bothers to do this, because it would be expensive and the normal amplifiers are good enough for the majority of people.

> Vacuum-tube amplifiers are not in the same class with techniques that are unlikely to have any perceptible influence on what you hear.

Yes, they are. The Carver Silver 7 was built to demonstrate this. [1] It's a tube amplifier with 38 tubes per channel that costs $17,000. It has all the important features - weighs 68Kg, vibration damping mounts, takes four minutes to power up, and the wiring is silver. Gets good reviews from the High End crowd.

Then Carver built the Silver 7 T, a transistorized amp with the same transfer function. As a demo, the Silver 7 and the Silver 7 T can have their outputs differenced, or wired up to cancel and drive a silent speaker. Same output. Gets terrible reviews.

[1] https://hometechnologyreview.com/CARVER-SILVER-SEVEN-MONO-VA...

> It is not at all clear which should be the output impedance of the amplifier as a function of frequency to ensure the least degradation of the sounds in comparison with the input signal.

> So it may happen that a vacuum-tube amplifier - loudspeaker system has actually a better overall fidelity than a typical audio amplifier that was designed to demonstrate a much higher fidelity on a resistive load (because thus the transfer function is easy to measure and correct, unlike the complete transfer function to sounds).

I don't know the electrical engineering at all, but I thought that this was a solved problem -- or that the degradation and mismatch were effectively negligible, well below the point of inaudibility.

>In theory, one could make a modern amplifier reproduce any quirky behavior of vacuum tubes, e.g. a higher and frequency-variable impedance or certain kinds of distortions, but usually nobody bothers to do this

Don't almost all transistor guitar amps do this?

> Vacuum-tube amplifiers are not in the same class with techniques that are unlikely to have any perceptible influence on what you hear.

I don't disagree. Not in the same class, but the audience overlaps.

> one could make a modern amplifier reproduce any quirky behavior of vacuum tubes, e.g. a higher and frequency-variable impedance or certain kinds of distortions, but usually nobody bothers to do this, because it would be expensive

In other words, the willingness to pay for OG tube amplifiers exceeds the willingness to pay for the sound thereof. I'm not sure you disagree with me either.

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