Phono Preamp Tube Rush

Tubes are inherently tweakier than solid state.  You can have tubes that have gone a bit 'microphonic' that need to be weeded out as a first step.  Power up the phono stage with the cover off and the volume at midrange, and very gently tap each tube with a pencil eraser and see what comes out of the speakers - a bad tube will be pretty obvious and I've had bad ones even in brand new batches.

Gain mismatches with a low output moving coil cartridge into a tube phono stage running at almost full volume are likely to give you some noise. If you listen to rock music with limited dynamic range that still may work for you, but on music with greater dynamic range you are likely to hear noise.  Consider the SUT that several have suggested - they work quite well - as long as you set the impedance correctly, assuming that it is adjustable on your unit.

And unlike solid state gear, you have a whole new set of non-soldered contacts that can get dirty and make unreliable contact and will need cleaning (usually every few years)  I'll leave the cleaning procedure and materials to someone else to explain.

Get the contacts right, and the tubes non-microphonic and the gain correct and it still may be a noisy pre-preamp for your system.  Which is why I run a solid state phono pre in my main system, which otherwise uses all tube amplification.  If you get a tube phono stage operating well for you, don't get upgraditis and get something else - you may well regret it.  I have had a tube phono stage in my second system (which ironically is otherwise all solid state) for some time and it is quiet and really quite good (CJ Premier 15). I have no intention of changing it any time soon.

I've just skimmed the thread and so may have  missed it, but nobody has mentioned low noise tubes.  I have found the NOS JAN-Phillips 7981's sold by The Tube Store to be substantially below stock tubes in my Brown Audio Lab headamp.  I also own a Counterpoint SA-2 headamp, and in that unit tubes are paralleled to achieve the same effect.

This is a topic I’ve been following for awhile. Although I’m not an EE, I do know I hear what I believe is tube rush from my Aesthetix Rhea eclipse phono pre. I’ve tried to ensure good connections from the cartridge all the way to the pre. I also found I had some RFI or EMI from a google mesh wireless extender that was positioned too close to my TT/cartridge.

But I can say unequivocally that going to ultra low noise 12AX7 NOS tubes (amperex) in V1 and switching from 6922 to 7308 ultra low noise amperex made a big difference. It did not eliminate but the rush but it is now very tolerable. And with the low-noise telefunkens in the other tube slots, a very very enjoyable sound. 

Harry, you did not read the thread carefully enough. I mentioned them way in the beginning.

Mike

I far prefer tube-based circuits to solid state, for sound quality, but all tubes do have a finite life span, and as the end draws near, they become noisier, until they reach a final common pathway of being noisy.  This malady will affect SLN tubes as well as non-select samples.  The variable is time from new to noisy, which is impossible to predict for a given sample of a new tube, but I would agree that for a tube that starts out SLN, perhaps (on average, but there are no guarantees) the time to its becoming noisy will be longer than for a non-select tube.  But the point I was trying to make earlier is that circuit design also has a lot to do with "noise" one perceives over the speaker.  For one example, ARC stuff was always known for driving tubes very hard, near their recommended limits for voltage and current.  In the old days, this led to short lifespan. Circuit layout also has an effect.  What tubes are chosen for a given task also has an effect.  Someone wondered why Herron(?) didn't choose to use a 6DJ8 instead of a 12AX7 in its phono stage; the simple reason is you could never get enough phono gain out of a 6DJ8, used as Herron uses the 12AX7.  The 12AX7 is a standard choice used in common cathode mode for the input of an MM phono stage; all the gain is done at the input before RIAA, as Hagtech mentioned.