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previous: DavidB Hi Lion,what grounding configuratio... -- 1/8/2000 7:23 PM

Re:Thanks RG and Randall!

1/9/2000 4:36 PM
lion	Re:Thanks RG and Randall! David This is what I ended up with! First thing – 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 – physically placed 1.5 " from the first filter cap. (This was the most convenient – but I’m not sure if it’s 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 Randall’s descriptions) - the PI grounds - the bias circuit grounds - the OT secondary (Randall stated that if there’s no NFB – which is the case in my amp – it’s 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 I’m still not sure that I fully understand this part. I’ll also mention that I had a problem with one of the filter caps – 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 I’ll just note that my 6.3VAC CT is lifted above ground with a 1M/100K from the B+. I haven’t check if this has any effect with the new grounding scheme – I just had it that way and figured I’d just leave there. Hope this answeres your questions. Regards Lion

1/9/2000 4:36 PM

lion

Re:Thanks RG and Randall!

David
This is what I ended up with!

First thing – 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 – physically placed 1.5 " from the first filter cap. (This was the most convenient – but I’m not sure if it’s 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 Randall’s descriptions)
- the PI grounds
- the bias circuit grounds
- the OT secondary (Randall stated that if there’s no NFB – which is the case in my amp – it’s 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 I’m still not sure that I fully understand this part.

I’ll also mention that I had a problem with one of the filter caps – 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 I’ll just note that my 6.3VAC CT is lifted above ground with a 1M/100K from the B+. I haven’t check if this has any effect with the new grounding scheme – I just had it that way and figured I’d just leave there.

Hope this answeres your questions.

Regards
Lion

Replies:

DavidB Yes,thank you!Ah chasing the invisi... -- 1/9/2000 5:02 PM