Hi, That is where it ought to go, same for the output transformer ground.
"One more question. Is the connect position of power supply bus, signal ground bus and the other direct ground connections (LM317HVs, maybe opt ground) on the central ground bus important? I mean the sequence of them on the central ground bus."
This is an excellent question.
Yes the sequence often does matter. All conductors have some resistance. Any time a current passes through a resistance a voltage is developed. If you have a high current source sharing a ground with a sensitive signal source it can introduce noise and sometimes hum. The complication is that both need to be at close to the some potential also to reduce noise. So the way they are arranged on a buss can alter the noise level. A really low resistance "buss" will often make the noise level from an incorrect arrangement very small and it might be insignificant. The way I like to sequence things on the buss is starting from the input signal grounds and shield ends of any shielded wires, to the small signal portions of the circuit, to the output ground (so the NFB if used has good access to the signal side) then the big signal stuff (like the cathode circuit of the output tubes) then finally the power supply ground. Remember that all this is typically in my builds on a 2-4 inch long #12 bare copper wire. The actual resistance between any point is realy quite low, but if you dump 200ma (like the cathodes) into it there will be some noise and that can end up being amplified by the voltage amplifier section. The arrangement is not as significant in low gain circuits, but can cause significant problems in high gain ones like phono preamps.
The grounding arrangement rears it angry head in a more subtle way too. I have seen folks string the ground of one part of the circuit, like the signal section to the power supply ground and then to the input jacks. Also folks using the shields of wires (inside gear, not outside between equipment) to carry the ground connection to various parts of the circuitry. This will nearly always introduce a significant amount of hum and noise.
Good listening
Bruce
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