You're grounding concerns will be about the small voltages that can develop on a grounding system because of the currents running through the ground cables combined with fact that the cables have resistance.
One stage of an amp can therefore have a part of its signal impressed on another stage of the amp by way of the ground not being all at the same voltage at the same time, and as an amp will normally amplify the difference between ground and the signal, this will cause problems. Another way this can happen is where noise is picked up on the ground cables and two stages therefore are sitting at different levels.
A logical and effective way to fix this is to bring all ground connections back to the same point as this 'point' will have one certain voltage on it and therefore all stages of the amp will be at the same ground potential. The next stage in cleaning the ground is to make sure your B+ and ground are properly positioned with respect to each other. Thus...
If you look at the last filter cap in a conventional power supply, (and assume it is the ideal low impedance source), you expect a clean source of voltage from it. From there, your ground point and B+ point can be star connected out to everything that needs it (yes, the B+ too).
However, before the filter cap you expect to have charging pulses at twice the line frequency as the cap is kept full from the rectifier side. If you were to connect your ground star point somewhere back there and since there is resistance on that ground wire, you'll get a voltage from those currents on your ground system with respect to the B+ (but not the stages with respect to each other if you're star connected, but the noise will still get through via the supply rails and the fact that the stages have only a certain amount of 'power supply rejection ratio'.)
Same on the other hand. If you connect your ground star point to the last filter cap via a length of wire, the wire will develop a voltage based on currents from all the amp and your ground will therefore not be steady with respect to your B+.
Your individual ground wires from each stage to the star point at the cap can have length. They'll only behave, for example, like very small extra cathode resistors causing no grounding problems, but the longer wires may be more open to interference that will affect only that stage. Inside the grounded chassis though, and properly routed, you should be OK.
If you have multiple ground connections on a single triode (grid resistor and cathode resistor etc.), theoretically you should ground them with individual connections to the star, but in practice this is not necessary. The connections are electrically so closely related that ground interference is hardly a concern, let alone a problem. Also, the connections are so physically close together that a really short and not too thin cable (between them all connecting them to the star return wire) can be used.
BTW, nice work on the chassis.
One stage of an amp can therefore have a part of its signal impressed on another stage of the amp by way of the ground not being all at the same voltage at the same time, and as an amp will normally amplify the difference between ground and the signal, this will cause problems. Another way this can happen is where noise is picked up on the ground cables and two stages therefore are sitting at different levels.
A logical and effective way to fix this is to bring all ground connections back to the same point as this 'point' will have one certain voltage on it and therefore all stages of the amp will be at the same ground potential. The next stage in cleaning the ground is to make sure your B+ and ground are properly positioned with respect to each other. Thus...
If you look at the last filter cap in a conventional power supply, (and assume it is the ideal low impedance source), you expect a clean source of voltage from it. From there, your ground point and B+ point can be star connected out to everything that needs it (yes, the B+ too).
However, before the filter cap you expect to have charging pulses at twice the line frequency as the cap is kept full from the rectifier side. If you were to connect your ground star point somewhere back there and since there is resistance on that ground wire, you'll get a voltage from those currents on your ground system with respect to the B+ (but not the stages with respect to each other if you're star connected, but the noise will still get through via the supply rails and the fact that the stages have only a certain amount of 'power supply rejection ratio'.)
Same on the other hand. If you connect your ground star point to the last filter cap via a length of wire, the wire will develop a voltage based on currents from all the amp and your ground will therefore not be steady with respect to your B+.
Your individual ground wires from each stage to the star point at the cap can have length. They'll only behave, for example, like very small extra cathode resistors causing no grounding problems, but the longer wires may be more open to interference that will affect only that stage. Inside the grounded chassis though, and properly routed, you should be OK.
If you have multiple ground connections on a single triode (grid resistor and cathode resistor etc.), theoretically you should ground them with individual connections to the star, but in practice this is not necessary. The connections are electrically so closely related that ground interference is hardly a concern, let alone a problem. Also, the connections are so physically close together that a really short and not too thin cable (between them all connecting them to the star return wire) can be used.
BTW, nice work on the chassis.
Here's what I think is most important.
:yes: 
