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I believe the common terminal of the output transformer's secondary winding should be attached to ground somewhere. It isn't needed for feedback purposes, but if the secondary winding is left floating, won't it tend to wander to some potential? I didn't see any mention of it in the assembly manual, and a quick search didn't seem to turn up any related topic in the GSG sub-forum. What is everybody else doing?

With no feedback, grounding the output side of the transformer
isn't necessary. The only thing connected is the speakers,
and they are not grounded in any way. The output is more
"passive" than active - no DC potential exists.

*bzzzzzzt*

I've done both and will definately ground one end, even through a resistor as a static bleed.

Even on the best transformers, the leakage can give you a tingle.

If you're custom winding OPT's for a zero NFB amp, get the secondary centre tapped and ground the centre tap - no ground hum imbalances that way.

Cheers!

Even on the best transformers, the leakage can give you a tingle.

A tingle on what ? I don't know anyone that touches their
speaker leads with the amp turned on. If the speakers
are connected, their low impedance would squelch whatever
"tingle" you are talking about.

Tom, that's why it's called an accident

And it's not just us, it's guests, kids, pets, etc.

Why tempt fate?

I had already decided that grounding them is was I wanted to do. I was curious about what others were doing. Judging by the photos, it seems that Ed grounded his OPT common as well.
http://www.diytube.com/phpBB2/viewtopic ... 63&start=4

I'm trying to figure out where is the best place to ground them. I've got a couple of choices on my mind. There is an extra ground screw on the terminal block next to where the high voltage secondary's center tap gets grounded. I could use the terminal for the audio signal ground, where the RCA input jack is connected. Or finally, I could just pick a nearby bolt on the chassis and use that.

I like Geek's idea of putting a large valued resistor in series with the connection, although I don't think I've seen that in use before.

Judging by the photos, it seems that Ed grounded his OPT common as well

He also fused the Neutral.

TomMcNally wrote:

Judging by the photos, it seems that Ed grounded his OPT common as well

He also fused the Neutral.

Oooops!

I noticed that a while ago, it has since been corrected...

Even neutral-fusing is better than Heathkit's no-fusing...

I generally ground the OPTs' secondary "zero" to the chassis, if not the actual ground buss. If anything, that may reduce RFI and other electrical noises entering via the speaker leads.

/ed B

EWBrown wrote:Even neutral-fusing is better than Heathkit's no-fusing...

You mean the famous "hope to God their breaker works" fusing method so common of that era