Phono Preamp Tube Rush


Is there such a thing as a tube phono stage that doesn't have tube rush? Is it just an inherent weakness of that type of pre or is it some combination of cartridge gain and preamp gain? I went from a silent solid state ASR Basis Exclusive to a Herron VTPH-2A (new home with space limitations) and now I'm using a Hagerman Trumpet with my Decca London Super Gold. Both the Herron and Hagerman have tube rush. The Hagerman beats the Herron in my setup and it really sounds incredible but in quiet passages and between songs, there's that hiss at high-medium and high volume. It's just there. No combination of new tubes, new cables, etc changes this fact. Same with the Herron. Anyone having a different experience with a tube phono preamp?
dhcod

Showing 4 responses by atmasphere

the only reason I raised the issue of Johnson noise was in response to a question about whether any tube-based phono stages are quiet enough for hiss to be inaudible when one’s ear is placed against the speaker, while a record is not being played. And my response was to the effect that for typical combinations of system gains, sensitivities, and volume control settings theoretical limitations might come into play which could make that impossible, or close to it.
*If* the phono section has sufficient overload margin yet still has plenty of gain (60dB) and a stepup transformer, you can get so much output out of the phono section that the noise floor of the line section will obscure that of the phono section- such that switching between Aux inputs and phono will not have an audible change to the noise floor even with your ear pressed to the loudspeaker drivers. I've demonstrated exactly this at shows.
I then extrapolated from that number to the result corresponding to the 12 ohm resistance of my cartridge, over a 20 kHz bandwidth:
@almarg Most LOMC cartridges have bandwidth well past 20KHz- most have no worries going to 40KHz.
if executed in the balanced domain you get a maximum of 6dB less noise
Actually, that's not true. With balanced amplification you get 6dB more signal gain, but you also get 6dB more differential noise gain. Overall SNR is the same.  

IME you get the same gain- not 6dB more. We might have to straighten out our terms here- it might be that we are talking about the same thing.


I would like just a little more gain for ultra low output cartridges and I believe from what I have read that a balance design should have lower noise levels. Cartridges are balanced to begin with.
The reduced noise can be significant. For a given gain stage, if executed in the balanced domain you get a maximum of 6dB less noise. Now if you have two gain stages or more this adds up.
I have never heard an ARC phonoamp with "tube rush."
I think you will find that ARC uses semiconductors at the input of their circuits as well.