I have some experienced. I tried Sylvania 3 mica, RCA 3 mica, GE 5 Star 3 mica, and Raytheon 2 mica all have black plates. My conclusion is that if you are using a cartridge which is 0.8mV or lower in output (MC), I tried the Shelter 901 and Denon 103R, the gain is not sufficient to have a flat response on the mid range even if you have a step up tranny(I am using Tribute wired at 10X).
However, for a 0.8 mV output (Benz ACE M), with a step up tranny, it sounds great and it is probably safe to assume that it will work with other cartridges higher in output than 0.8 mV.
Difference? Less tube rush at higher volume for sure but sonics wise, I prefer the Sovtek 12AXLPS or Tungsol 12AX7 with either Amperex BB large ring getter 12AU7 or RCA Blackplate 5814 square getter. Here are some combo that I found(from being a new owner of the Cornet 2) that works with my system....
Tungsram 12AX and Telefunken Smooth plate 12AU
Mullard 12AX and GE 6189
Amperex BB 12AX and Amperex BB 12AU or RCA 12AU
Matsushita 12AX and RCA 5814
Sovtek 12AXLPS and EI 12AU
Ahhhh, pretty confusing isn't it? IMHO, the Cornet 2 is great sounding with any tubes but with the right tubes, it's magical! If you do not have a stable of cartridges of different output range or preferably MM, I would say stick with the 12AX7's or else you will be stumbling to rewire your step up for a higher gain.
My own conclusion? The 5751 works better on MM cartridges and higher output MC cartridges than the 12AX7's on the Cornet 2 in my system.
As what
GRD said above, the RIAA equalization of the preamp is directly affected by the rp of the tube. Hence for a 12AX7 whose rp is from 62500 to 80000 ohms and for a 5751 whose rp is around 58000, there will be a swing because of the discrepancies. Hmmmm.....that should be the reason why I thought the gain on the mid using 5751 is not sufficient for getting a flat response.
Pardon me Robert, but I have a question for Jim and others.
Question: looking at the schematic of the Cornet 2, the RIAA is R204,R205 C202, C203, R207 isn't it? Is it safe to assume that R208 in Series with the 2nd 12AX7 Rp is the one tilting the balance of the RIAA if 5751 replaces the 2nd 12AX7? If that is the case, the 2nd 12AX7 position can be "rolled" to tailor the RIAA response more effectively than the first 12AX7? Or I am getting this all wrong
