Valve phono stage

@infection I mentioned earlier about how you can't just buy tubes off the shelf and expect them to work in a high performance circuit.
Lew's advice is good- those tubes are in there for a reason. This isn't saying that you can't do better- you can, just expect that when you buy a hot-shot tube be it boutique or NOS, that it may not be as quiet or low microphonics as you expected and you may have to return it and try again.

We buy tubes 100 at a time, so we have more examples to go through to find the tubes in the box that sound right. I'm sure that's what Keith is doing too.

Still have some amazing NOS tubes left, such as ECC801 / 12AT7 WA, not sure is there is any valve phono stage with this type of tubes.

We use 12AT7s in all our phono sections. Not as much gain as a 12AX7, but a lot more bandwidth.

Purist is pretty nice- not sure it they fit the budget.

as a disadvantages i can add:
Tube Microphonics, Tube Noise, Tube Rolling effect (you change the tube and you change the sound). The price for each good tube, the tube estimate hrs and short life of the tube (not good for very expensive nos).  

This statement is quite true, but I should point out that in any high performance audio equipment, whether tube or solid state, the devices used have to be hand picked- you can't expect to just buy them off the shelf and have them work.
Some years back we experimented with semiconductors at the input of our MP-3 preamp. What we found was that regardless of the MOSFETs we tried, we had to hand pick them and out of 100 units, we found only about 7 that were quiet enough for use. In that regard we had an easier time hand-picking the tubes!

MM cartridges are of course a different animal as loading affects them directly, otherwise they can ring and cause distortion. The loading is usually a bit more complex- did you read the comments Jim made about them in the article I linked?

How many great tube phono stages available for less than $1k , not for $3k? Just curious.  

At least two that I know of- but that IMO is a loaded question. In the preamp I'm thinking of the phono section causes the preamp to cost about $400 more that it does as a line stage. In another example the phono section raises the cost of the preamp by about $800.00; so I think the answer is probably a lot like 'a bunch'.

Any tube fan can explain me what is the advantages of the tube phono stage compared to the great SS design?

It can be explained. Whether you accept the truth of the matter is a different thing altogether.
The primary advantage of a tube phono section is reduced generation of higher ordered harmonics. This is why tube phono sections tend to sound smoother than solid state.
As I pointed out earlier on this thread, another advantage is that it is much easier to design a tube phono section that has good overload margins and good resistance to RFI (semiconductors more easily rectify Radio Frequency signals since they have diodes built into their structures). The advantage of this is less ticks and pops during playback. This phenomena is not well-known; nearly all of the phono preamps in Japanese amps and receivers on the 1970s clear though the 1990s were not good in this department and so made a lot more ticks and pops than are actually on the LP surface. So an entire generation of audiophiles grew up thinking that ticks and pops are endemic to the media. In fact such is not the case!
We should not ignore the 'cartridge loading' issue, which is related to this latter point. Cartridges need to be loaded with many phono sections, not because it helps the cartridge in any way, but because the inductance of the cartridge combined with the capacitance of the tone arm cable creates an ultrasonic/ RF resonance that is driven into excitation by the energy of the cartridge. This resonance can be a good 30-35 db more powerful than the signal from the cartridge (IOW over 1000 times more powerful) and many phono sections (in particular solid state) really don't like the RFI thus presented at their inputs and so don't sound right. This is why overload margin is so important- the overload caused by this resonance is where many ticks and pops originate.
Now if you have to load the cartridge to get it to sound right, what happens is the energy from the cartridge has to drive that load since it is a direct shunt to the cartridge signal. The result is that the mechanism of the cartridge becomes stiffer and less able to track, especially at higher frequencies. This is very similar to how an amplifier damps a loudspeaker cone and is easy to demonstrate. If you doubt me on this, take a raw loudspeaker and tap its diaphragm, then short its terminals and do it again. You will see that the speaker got a **lot** stiffer- the same thing happens with a cartridge, as the operating principle is the same.

So the ability of the phono section to operate correctly with the stock 47K load is pretty important- when you load the cartridge at significantly lower impedances, like 100 ohms, you are robbing the cartridge of its last bit of performance!
If you think I'm making this stuff up, talk to JCarr of Lyra, he has written extensively on this topic. He is by no means the only one, here is a helpful article from Jim Hagerman on the topic (which does the math on cartridge resonance):
http://www.hagtech.com/loading.html

In a nutshell, the result is that a good tube phono section will often be less irritating (smoother sound, less ticks and pops) than a good solid state phono section and for the reasons stated, can have greater resolution too (extracting more detail from the LP).

Facts contradict your salemanship approach on balanced connections.

@bpoletti  Perhaps you could point me to a link that confirms your position?
Here is a link that confirms mine:http://www.rane.com/note110.html
Scroll down, you'll see a diagram of a transformer hookup. Note that the secondary of the transformer is floating (like a cartridge, the secondary of the transformer is a simple coil with only two connections), per the Balanced Standard, also known as AES (Audio Engineering Society) file 48. There is a charge for the AES paper on that topic, so I can't link that, but here is a google search on 'balanced cartridge connection', also confirming my position:
https://www.google.com/search?client=ubuntu&hs=5U8&channel=fs&tbm=isch&q=balanced+ca...
Note how the cartridge is represented by a simple coil with two connections.

So I would be interested in your source(s).

Regarding sales, it is true that I push balanced line operation. IMO/IME it sounds better and no looking back. My exposure to balanced lines occurred in high school, when I was tapped by a local college to play string bass in their orchestra (1973, Macalester College, in case anyone cares).  At the concerts, I noticed a pair of Neumann U67s hung over the orchestra, with some very long cables going up to a very high ceiling and from there going back down to a booth on the side of the hall. Inside the booth was an engineer named Mike Shields (for real, not a made up name) and a Crown reel to reel, running the balanced line connections from the mics straight into the machine.

It was from those concerts (and his headphones) that I learned that you can run very high quality low level audio signals a really long way without degradation. That seemed a logical thing to incorporate into a phono section when I was designing one years later, not so much for the length of cable but for the additional sound quality. So the world's first balanced line preamp, which incorporated the first balanced line phono section, was the MP-1 preamp, which we still make.

A bit of audio history for you; the MP-1 brought balanced line connections into the home for the first time. Sorry if I still enjoy my work.

No single tube audio item ( everything the same ) can compete with SS designs as your Whest in some critical issues when we are talking of LOMC cartridges: noise levels, distortions levels, frequency response bandwindth, RIAA eq. deviation levels, output impedance level, etc etc.

This statement is obviously false. If it were true, there would be no vacuum tube phono sections.

so why do top phono stage designers use RCA inputs?

Tradition- rather than performance.

Take a very close look at phono cart signal generators. Doesn’t matter if the cart is MI, MM or MC. They are NOT balanced, they are single-ended with a + and - pole. One strand of wire that runs from the hot side of the connector to the ground side. No neutral.

This statement is false.
bpoletti, it seems to me that your misunderstanding is the idea that in balanced operation there has to be a ’neutral’ connection- like a center tap on a transformer or the like. IOW, are you expecting that if a cartridge is balanced, it would have six connections? It really doesn’t work that way! How it *does* work is that the winding of the cartridge floats with respect to ground, IOW neither side is tied to ground, instead the arm tube is the ground (its a shield) and other than shielding, the arm tube is not involved with the signal in any way. That is how a balanced system is supposed to work.

If there was a center tap on the cartridge winding, and if it were tied to ground, performance would be reduced because the center tap could never be perfectly placed. That is why balanced systems don't have a center tap- the coil always floats whether its a cartridge, microphone or transformer.

When you run the cartridge single ended, you wind up with the weird ground wire that no other single-ended source seems to need. That is because you are taking a balanced source and running it single ended- and you wind up with a ground wire.

So when we run the cartridge signal into our MP-1 (which in 1989 was the world’s first balanced line preamp), the tone arm ground wire is tied to pin 1 of the XLR, which is ground. The ’+’ output of the cartridge is tied to pin 2 and the minus to pin 3 (pin 2 being either the red or white wire of the tone arm, depending on which channel). This is why a 5-pin DIN tone arm connector is a true balanced connection, since neither channel is tied to the ground and the ground is thus the shield of the interconnect cable.

The advantage of this system is you simply don’t have to have an expensive cable to get it to sound right, a low capacitance cable that is constructed properly is all that is needed, and it will easily keep up with any exotic tone arm cable made, cost no object. Its a pretty clear (if you will pardon the expression) advantage.

I appreciate your suggestion but I want a dedicated PS.

@infection 

FWIW, an outboard phono section has some problems to overcome. The main one is connectivity- if you have ever had to audition interconnect cables then you know what I'm talking about.
When the phono section is hard wired into the preamp this problem is avoided. In addition the input and output impedances are controlled- so the phono section can perform as the designer intended.

Not considered that... would you say I should?

Since the cartridge is a balanced source, the advantage of having a balanced input is once again that of the connection- balanced lines exist for the sole purpose of minimizing sonic artifacts that can otherwise occur in the cable. Again, if you've ever had to audition cables you know what I'm talking about.
This should be a boon to audiophiles- it means that an inexpensive cable can perform as well as the most expensive cost no object!
Since all low output moving coil cartridges have a very low impedance, the result can be that you don't have to have an expensive cable to make it work in your system and have the tone are cable be absolutely transparent- which is the most important place for transparency to happen- no matter how good your gear is, it can't make up downstream for losses upstream!

So there is a pretty potent argument for running a balanced input, otherwise you are leaving performance on the table.

Do you want balanced inputs as well?
Phono cartridges are a balanced source...