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|previous: DavidB Hi Lion,what grounding configuratio... -- 1/8/2000 7:23 PM||View Thread|
|1/9/2000 4:36 PM|
|lion||Re:Thanks RG and Randall!|
This is what I ended up with!
First thing Ė input and output jacks isolated.
I chose the cap closets to the PT CT and made this one my first filter cap.
The ground lug on this cap is my first star point.
Other grounds wired to this lug is:
- the PT CT
- the output tube cathodes (it made a huge difference!)
My second star point is a lug bolted to the chassis Ė physically placed 1.5 " from the first filter cap. (This was the most convenient Ė but Iím not sure if itís the best place?)
The rest of the grounds is wired back to this second point with seperat wires:
- the common local preamp grounds (as per RG and Randallís descriptions)
- the PI grounds
- the bias circuit grounds
- the OT secondary (Randall stated that if thereís no NFB Ė which is the case in my amp Ė itís not allways needed to ground the OT secondary at all. I tried it both ways and it made a huge difference to the better with a connection from the output jack sleeve back to the second star point.)
The first star point (the filter ground lug) is connected with the second star point (the bolted lug) with a short thick wire. It was actually this detail that made me confused for a while - and Iím still not sure that I fully understand this part.
Iíll also mention that I had a problem with one of the filter caps Ė being a different type than the others. It was one of those with the ground connected to the can so it would ground to the chassis by the mounting clamp. Had to isolated it.
Last Iíll just note that my 6.3VAC CT is lifted above ground with a 1M/100K from the B+. I havenít check if this has any effect with the new grounding scheme Ė I just had it that way and figured Iíd just leave there.
Hope this answeres your questions.
|DavidB Yes,thank you!Ah chasing the invisi... -- 1/9/2000 5:02 PM|