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PostPosted: 24 Nov 2018, 11:09 

Joined: 23 Nov 2018, 19:41
Posts: 9
Hello Everyone,

I'm new to the forums and to vacuum tube amplifier building as well. I'm preparing to build the SET 6CY7 tube amp. I have noticed quite a bit of material online on grounding metal amplifier chassis. All this material has left me a little confused and with a few questions:

1) How can I ensure that my connection between the ground terminal and the chassis is robust? I've seen a few examples of folks who use a star washer between the terminal and the chassis, followed by the terminal, and then a star washer on top of the terminal, followed by the nut / screw. Is this a good method?

2) How can I avoid issues with oxidation and galvanic corrosion between a ground terminal and the amplifier chassis? How can I avoid issues with oxidation and galvanic corrosion between my conductors and the ground terminal I select?

3) Do aluminum chassis typically come with any type of coating that I need to abraid to ensure good ground connections? Specifically I'm looking at either a steel or aluminum chassis from Hammond MFG.

4) In a typical single ended vacuum tube amplifier build, what components if any should I try to isolate from the node established by the grounded metal chassis? For example, I see people mentioning that RCA signal jacks should be isolated from the chassis with an insulating washer.

5) Am I correct in my understanding that all signal grounds' zero or reference node is the star grounding point in common potential with both the neutral outlet port and the amplifier chassis? I.e. only the power transformer connects to the AC negative terminal?



PostPosted: 25 Nov 2018, 16:31 

Joined: 13 Jan 2018, 21:33
Posts: 406
Location: australia
Hi and welcome. The content experts may respond to specifically address your query but at the link following is a kind of knowledge bank that includes a grounding techniques primer. Not too sure whether corrosion is addressed though by Gofar99.

Suncalc also advised the following in relation to a query i had ...viewtopic.php?f=9&t=4632&p=54394&hilit=grounding#p54394.

Hope this helps.


PostPosted: 01 Dec 2018, 17:25 
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Joined: 04 Jun 2008, 20:59
Posts: 4361
Location: Arizona, USA
Hi, Unless you are in an area that has problems with corrosion I would not worry about it. In all the projects I have built over the course of about 50 years this has never occurred and caused a problem. I use the toothed star washers between the chassis and component needing to be attached to it. They work just fine. The only chassis that need to be scraped are ones that are painted or powder coated. BTW, beware of transformers with painted or powder coated mounting feet. They too need to be scraped and have a star washer to insure grounding of their cases.

On grounding...I find that all signal grounds need to be isolated from the chassis and only the AC mains ground should go there directly. It must to comply with nearly all electrical codes. The signal ground system can connect to the chassis in several ways. I prefer to use an X2 type capacitor with parallel resistor. Others use opposite facing rectifiers in parallel.

Good listening

Some of my DIY Tube Amplifier Projects:

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