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.
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
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: Charles1dadA couple of factors that may contribute to that in some cases, in addition to the performance characteristics of the particular equipment:
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.
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