Hi S1,
Up front, I'm using a Lorenz PCC88 Grey Shields made in Stuttgart Germany.
I have finally settled on this after comparing it with other tubes such as the famous Siemens CCa Grey shields, Valvo Holland CCa Grey shields, Telefunken Tubes and a Frenchmade Philips E188CC amongst many others.
I have a pinched waist Amperex 6922 landing at my doorstep soon. I expect a "Clash of the Titans" to take place very soon.
![Wink Wink](https://www.decware.com/yabbfiles/Templates/Forum/default/wink.gif)
BTW, I think Steve will be able to comment on the accuracy of my hypothesis. If you refer to the preamp design notes over here,
https://www.decware.com/paper56.htm and scroll all the way to the last paragraph, the CSP preamp was designed such that the 5Y3 rectifier would run your smaller tubes at the lowest voltages. The use of a 5U4 based rectifier would be more taxing on your 3 tubes by running them at a higher voltage.
As I mentioned earlier, I have tube-rolled almost all makes and brands of tubes such as Siemens, Philips, Valvo, Telefunken, Lorenz etc in my CSP2+. The only consistent tube throughout was the use of a Tung Sol 5Y3GT rectifier. I believe that because I have been tube rolling at the lowest voltages, I have not experienced any of the tube arcing phenomenon. This is just my hypothesis and hopefully Steve can verify this?