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Two-point star ground Q’s – long

1/5/2000 3:33 PM
lion	Two-point star ground Q’s – long In order to improve the SN-ratio in a DIY amp project, I’ve been gathering info on grounding principles. Until reading the tech-paper on Randall Aikens excellent site, most sources I’ve read, refers to a one-point starground scheme. In the article (www.aikenamps.com/StarGround) Randall Aiken states: "Even better is a two-point star....." The article is pretty detailed – but yet there’s a couple of things I’m not sure about, so I thought I’d better seek some advise before redesigning my grounding scheme. The layout off my amp is with the PT in one end off the chassis and 3 radial double cap cans mounted in equal distance (4 cm) round the PT. Not in a straight line arrangement. My doubts is regarding the physically placement off the two grounding points. "The ground lugs for the capacitors can then be connected to the chassis in such a manner as to keep the later stage ground currents from interacting with earlier stages." If I’ve got it right, the first ground point should be a lug ,bolted to the chassis, close to the PT – and preferably on the edge off the chassis. The ground wires from PT center tap, first filter cap, the output tube cathodes (fixed bias), filament center tap and the OT secondary ground connects to this first ground point. The second ground point connects with all the local common preamp stage grounds and the remaining filter caps – the ones after the choke. (Input and output jacks isolated) BUT - is the second ground point another lug bolted to the chassis – and where should I place it. In the preamp end off the chassis - as far from the first ground point as possible? Or close to the second filter cap – which, in my case, is also close to the PT- and the first ground point? What influence, if any, will the placement off the choke and OT have? I’m also not sure where to connect the bias circuit grounds! Any info, advise or comments will be highly appreciated. Thanks. regards Lion

1/5/2000 3:33 PM

lion

Two-point star ground Q’s – long

In order to improve the SN-ratio in a DIY amp project, I’ve been gathering info on grounding principles. Until reading the tech-paper on Randall Aikens excellent site, most sources I’ve read, refers to a one-point starground scheme.

In the article (www.aikenamps.com/StarGround) Randall Aiken states:

"Even better is a two-point star....."

The article is pretty detailed – but yet there’s a couple of things I’m not sure about,
so I thought I’d better seek some advise before redesigning my grounding scheme.
The layout off my amp is with the PT in one end off the chassis and 3 radial double cap cans mounted in equal distance (4 cm) round the PT. Not in a straight line arrangement.

My doubts is regarding the physically placement off the two grounding points.

"The ground lugs for the capacitors can then be connected to the chassis in such a manner as to keep the later stage ground currents from interacting with earlier stages."

If I’ve got it right, the first ground point should be a lug ,bolted to the chassis, close to the PT – and preferably on the edge off the chassis.
The ground wires from PT center tap, first filter cap, the output tube cathodes (fixed bias), filament center tap and the OT secondary ground connects to this first ground point.

The second ground point connects with all the local common preamp stage grounds and
the remaining filter caps – the ones after the choke. (Input and output jacks isolated)

BUT - is the second ground point another lug bolted to the chassis – and where should I place it. In the preamp end off the chassis - as far from the first ground point as possible?
Or close to the second filter cap – which, in my case, is also close to the PT- and the first ground point?

What influence, if any, will the placement off the choke and OT have?
I’m also not sure where to connect the bias circuit grounds!

Any info, advise or comments will be highly appreciated. Thanks.

regards
Lion

Replies:

Dave H. q{BUT - is the second ground point ... -- 1/5/2000 5:07 PM
DavidB Yeah,I think you would bolt the pre... -- 1/5/2000 6:23 PM
Todd Hepler Does this forum read minds ? -- 1/7/2000 8:10 PM
Whit Re: Two-point star ground Q’s – long -- 1/10/2000 5:57 PM