I have a general question about the order that component grounds should be connected to a buss bar in a tube phono preamp with p2p wiring.
This is what I think for buss bar order:
Chassis - Input - 1st stage - 2nd stage - output stage - (B-) - (H-)
I am not referring to the safety ground, to me that is an entirely separate entity.
Am I thinking correctly?
Thanks
This is what I think for buss bar order:
Chassis - Input - 1st stage - 2nd stage - output stage - (B-) - (H-)
I am not referring to the safety ground, to me that is an entirely separate entity.
Am I thinking correctly?
Thanks
That seems sensible. You can also ground H+ and H- to the chassis with a pair of 220 ohm 1/4W resistors.
Thanks, if I did that then I would not connect it to the buss?
I have also seen some builders ground the buss bar to chassis through a resistor. I wonder about the need for that though.
Yes, you can add that resistor between the chassis and the buss bar. I find this helpful with noisy powerlines.
For clarity, the H- connection point is at the heater transformer secondary, not the H- connected to the tube filament / heater point. Correct?
No I am referring to the negative leg (or return leg) of the heater circuit, more specifically DC heaters.
The B+ negative supply lead is either the center tap of the B+ secondary, or it is the Bridge rectifier negative output.
The negative of the B+ supply lead needs to connect directly to the negative of the first B+ filter cap. This is a minimum distance hum and noise ground loop. Good.
After that, put a separate wire from the negative of the B+ first filter cap to the buss bar.
If instead you connect the negative of the B+ supply (secondary center tap, or bridge negative out) to the buss bar, and connect the negative of the first filter cap to the buss bar, you have created a much longer hum and noise ground loop. Bad.
The negative of the B+ supply lead needs to connect directly to the negative of the first B+ filter cap. This is a minimum distance hum and noise ground loop. Good.
After that, put a separate wire from the negative of the B+ first filter cap to the buss bar.
If instead you connect the negative of the B+ supply (secondary center tap, or bridge negative out) to the buss bar, and connect the negative of the first filter cap to the buss bar, you have created a much longer hum and noise ground loop. Bad.
your right, in general buss bar order is with the highest current draw circuits at one end, with the least current hungry at the other. It's a good idea to to connect your HT/B+ ground right near the OP stage/OPT secondary ground..
Andy.
Andy.