Lab12 Melto 2 - tube rolling

@lalitk for almost a year I had possession of a friend’s CH Precision P1 and had ample opportunity to AB the two.  The P1 at that time was the undisputed king of solid state and I believe the ART Phono is still the top tube phono preamp available.  I have not heard the new P10.  Anyway, neither one is perfect.  Either is wonderful.  They do sound different, but not as different as I presupposed they would.  Both are neutral, both are noise free.  I came to the conclusion that the ART was better (a weeny, teeny, to me, bit) on the low gain (47 k-ohm) input, the CH was better by a margin on the high gain input.  But with either I tended in the end to use my Consolidated 10:1 transformer, which meant in the end the ART was my preferred preamp.   If you get a chance to hear either take it.   

@lalitk yep I know that track very well and will be playing more of that album later today. Fade to Black is another great listen there. The first track, Elvis, has thunderous drums and man the Siemens tubes had them on display in full glory.
Another great track from the same album is “When It Comes To You”. I’ve heard cymbals on that track sound hard if the system isn’t dialed in. I’ll throw more music at Melto 2 before I swap in the 6H23P EB. Some Black Sabbath, my new favorite Scheherezade from Analog Productions. 
 

I’ll post more thoughts as I get more time with it. 

@billstevenson you never know if it can sound better unless you hear it. Could be worse too. But I doubt it will be the same with different tubes. At least based on my prior and current experience. Man I tried to stay away from tubes and tube rolling by selling my tube pre and amp several years ago…I guess that’s all down the drain…LOL

Lalitk, You wrote, 

"The tubes in output stage in theory has no voltage gain as @lewm pointed out but in real world, they behave quite differently.  A cathode follower has no voltage gain, it’s there to lower output impedance, provide current and buffer stages. So on paper, it shouldn’t influence the sound much, right…lol! 

But in real world, it still does. Tubes differ in transconductance and behavior under load, which affects microdynamics and low-level detail. They also shape the distortion profile, influencing tone, texture, and decay. Since a cathode follower is about current delivery not gain, how a tube handles dynamic current impacts attack, ease, and overall musical flow."

What you say here is quite true, but you are conflating differences among different tube types with differences among different brands of 6922 and its congeners. The performance of a CF is very dependent upon its plate resistance, mu, and most of all transconductance.  The output impedance of a CF is roughly equal to the inverse of its transconductance.  So to achieve the lowest output Z and the max current delivery at the output, you want tubes of highest transconductance. For this purpose, the 6922 and other high Gm/low Rp triodes are best. I like to use the 5687 as a CF but it does require lots of current, which is among its virtues as a CF but also puts demands on the PS.  This is also why the 12AX7 makes a terrible CF. (Very low current handling and very low Gm.) Among tube types, yes, performance as a CF will differ, but among 6922s that are performing within RCA manual spec, there should not be much difference.

That leads me to my next point.  I have found that any sonic differences among decent CFs can be ameliorated by adding a constant current source (CCS) between the cathode of the tube and ground.  The CF per se is a nonlinear device, and therefrom derives its character if it has any.  The CCS stiffens it up, makes it much more linear and transparent.  I have done this at least 3 or 4 times in different gear and always with a noticeable uptick in SQ. The caveat is you need enough cathode voltage to support the CCS itself. I realize that not many are going to try this, but K&K used to sell very compact solid state CCS kits, small enough to fit in most tube gear.  I've installed many of their kits. You won’t hear the dreaded sound of solid state, because a CCS by definition has a super high impedance, meaning the audio signal does not pass it.

@billstevenson 

Your recommendations on CH P10 and CJ Art phono’s are well noted. Unfortunately, they’re a bit outside my budget especially new, though I might get lucky on the used market. I’m trying to keep the phono stage under $20K so I can properly allocate funds toward the two cartridges….the Etsuro Gold and the Murasakino Sumile Mono which is already a $20K commitment.

Another reason I’m not leaning toward CH is that I want at least one tube component in an otherwise solid-state system, and the phono stage is really my only opportunity to do that. The rest of my setup is pretty much locked in.

That said, I’m keeping an open mind and really appreciate your input. At the end of the day, it’s all about finding that one piece that puts a big smile on your face.