what tube is that lurking in the background?
The amp is based on the 3GD4 rectifier (background tube); 6AS7 (I use 5998s) and 6SN7 (up front).
I now primarily use The Mighty 596 in the rectifier slot.
I use the 5998 tubes myself, mine are chathams also. Great tube
more dynamic with stock tubes? wait til you drop the metal base gZ34 in...
Here is the upgrade parts list...
1/ BlackGate NH 220uf/160V x 6
2/ RMG 470Ω resistor X 2
3/ RMG 220KΩ resistors X 4
4/ V-Cap CuTF 0.22uf/300V X 4
5/ BlackGate NH 150uf/350 x 3
6/ Mills MR-200 30.1k resistors x 4
7/ Gold plated Japan made selector
8/ Mundrof Silver Gold 0.5mm &1mm cable