Tubes in Hi-End Preamps


I’m confused. If some of you engineer types could pipe in on this subject, it would be greatly appreciated. I know a little, but not a lot about electricity. I’ve been in the battery industry for 20 years and have taken two semesters of college electronics, so I know just enough to be dangerous.

For 15 years, I’ve been sans preamp. The idea being that I don’t want anything messing up the source signal. That limits me to one source only though, and I’ve finally caved in to the need to be able to access multiple sources with the turn of a knob.

It’ll be nice to finally have hifi sound when I watch DVDs, and I would like to spin vinyl again after 20 years away from analog. To that end, I have an Audio Illusions Modulus 3A unit on its way now.

OK, here’s my question:

Why is it that many higher end preamps, Audio Research for example, that are said to be “neutral” and “transparent” sounding use tubes in their designs? Wouldn’t it be a lot easier and less expensive to build a solid state circuit that produces clean, neutral, and transparent sound? Aren’t tubes supposed to “color” the sound?

I've noticed the presence of a lot more equipment out there (the latest generation of some designs) with tube output sections that are described as not sounding "tubey." What's the point then of having tubes?

I hope I haven’t opened a can of worms here.
blumusician
Veridan, The key in this part of the discussion is not, IMHO, the presence or absence of distortions in the electrical signal but whether or not neutrality is an aural experience or a just a difference in the electrical signal itself which may not be audible.

When you take a strict approach by saying that neutrality cannot exist in the presence of distortion as measured by an electronic devise I would agree. However, if a premise is based on the surmise that the product of a distortion in the signal must be audible when heard to be meaningful, a different conclusion can be reached.

Personally, I do not believe we can hear the effect of all that we can measure if for no other reason than we have not the means (our equipment) or ability (our ears) to do so.

That is why it becomes necessary to define 'neutrality' before we can conclude whether or not it can exist.
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Viridian,

Sorry 'bout the name - I think my mis-spelling is the result of my mis-pronouncing it and not looking back. I'll be more careful - wasn't meant to be personal, just laziness on my part. :-)

As to elections of distortions, I'm a tube guy - I'll take a bit of 2d order harmonic distorion every time. Makes those sources sound more natural (neutral?) to me. And, at 10% and 2% I could well imagine that both should easily be audible.
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Viridian,

What I said was that 2d order harmonics sound more 'natural' to me. I parenthesized 'neutral'with a ? mark only to emphasize that I didn't think the my use of the term natural necessarily encompassed neutrality, but some might think these terms were identical in this context. That is, to be natural demands neutrality.

If I may digress a bit - I think many, myself included, are convinced that the best result in home audio is brought about by a careful matching of the speakers to room acoustics, the amps to the electrical requirements of the speakers, the pre-amps to the needs of the amps and sources, and lastly the sources to please the ears of the listeners.

None of these components need to be neutral to succeed in their function, in fact bending of the tonal balance by selection of certain components is often what makes a meaningful difference to the user because they need to compensate for other tonal imbalances brought about by compromises in the choice of room, speakers, amps, etc. They should all be highly resolving as pratical but tonally accurate (read neutral) is, for me at least, not necessary.

Some bend the tone with cable, IC's, tubes, PC's and even tweeks. But bend the tone they do and in the final analysis they have the tone that they feel is most natural, not which is not necessarily more neutral.

On a purist level, I will be very impressed when some one can prove to me, not just speculate, that they have been successful in actually replicating, or even coming close for that matter, to the sound that was recorded on the source. For those who might, I might ask if they were present when the recording was made and why they have such confidence in their long term aural memory.

Being a 'hair shirt' audiophile is no walk in the park! :-)