Ssssh, is your tube preamp really that quiet?

A point that hasn't been mentioned yet is that our ears, or at least MY ears :-) are significantly more sensitive to high frequency hiss when it is firing into them from the side, rather than emanating from a direction that is closer to the one that is being faced (as it would be under normal listening conditions).

FWIW I have never had a preamp in my system, tube or solid state, that was totally silent with my ear directly facing the tweeters from a distance of less than about 3 or 4 inches. That applies to both line-level and phono modes, and to any setting of the volume control, although the hiss level will of course increase somewhat in phono mode as the volume control setting approaches max. In my present system (solid state preamp), turning my head to face the tweeters, with my nose almost up against them, reduces that hiss level to being just about inaudible (except in phono mode with the volume control at or near max).

As Rodman indicate earlier, though, some or most of that hiss may originate upstream, due to EMI/RFI pickup, ground loop effects, or source components. I know it is not being generated by the amp or its interconnects, because it disappears when the preamp is muted.

03-24-14: Charles1dad
Ralph, What's interesting is that despite the noise you mention, once the music begins these "noisier" devices ironically reveal more musical nuance and low level information. As though the noise floor diminishes with the musical signal transmission.

A couple of factors that may contribute to that in some cases, in addition to the performance characteristics of the particular equipment:

1)I've read a number of times in the past that the presence of very low level high frequency broadband noise can be subjectively perceived as an increase in ambience. That seems credible to me.

2)Just speculating, but perhaps a phenomenon can occur as a result of the addition of very low level high frequency noise to analog signals that is akin to the improvement in digital signal resolution which results from the addition of dither.

Best regards,
-- Al

I have very efficient speakers and went through a number of tube preamps which had varying degrees of noise before settling down with the Herron VTSP-3A (R02). It is not only super quiet but also a very convincing performer across the board.

Yes, Charles1dad, you and I are of the same opinion in that regard.

Ralph,
I discovered this some years ago when I owned a Symphonic Line SS amplifier and a tubed Audio Prism el 34 tubed amplifier. The S.Line amplifier was quieter in terms of external noise than the tube amp. Yet when comparing the same recordings via these two amps the tubes revealed nuance,subtle-inner detail and emotion that wasn't apparent with "quieter" amplifier. It was as if the noise floor of the tube amp became lower once there was signal propagation activation. I sold the Symphonic Line amplifier.
Charles,

Hello Charles, the same thing happened to me although it was a different solid state preamp that I started with.

We can get such good gain numbers with the use of stepup transformers that at normal listening levels, you can't hear the phono noise over that of the line section and amplifiers regardless of the loudspeaker. But I have yet to find a stepup transformer that conveys the music as well the tubes do running directly.

Over the years we have experimented with semiconductors as well- super linear FETs and bipolar devices, and we have tried OP Amps as well. Try as I might, I can't get them to sound as musical as the tubes- I hear the same problems with the semiconductors in our stuff as I hear in the competition. So for the time being anyway, we are sticking with the tubes. They just work.