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Insulated input jacks on metal chassis? Grounding question.

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Just putting the final touches on my SSE and ran into a question. I have RCA jacks that came with insulated washers (they can be omitted though). If I ground the board through one RCA, as shown on the Tubelab site, I'm guessing this should also be in contact with the chassis.

What do I do with the rest of the input jacks? Should they be insulated or also in contact with the chassis/ground? Doesn't it create a grounding issue if they're uninsulated and also grounded through the volume control?
 
Or do I leave all the jacks isolated, ground the board through one input ground to the IEC and ground the chassis elsewhere directly to the IEC?

Or ground the board to the IEC and the chassis to the IEC? Looks like grounding the board would be straightforward using the other half of the screw down connector that the HV center tap goes to.
 
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Use the insulating washers for all of your input jacks and tie all of your signal grounds to one point (star ground) if possible. It's usually not a good idea to use the chassis for signal ground unless you are fond of hum.
 
Boy wonder, thanks for the tip. All my input grounds will then go to the board via the volume with one jack also grounded to the IEC (to provide a ground for the board). Then also ground the chassis to the IEC? The rest of the uninsulated components will then be grounded through the chassis.
 
Boy wonder, thanks for the tip. All my input grounds will then go to the board via the volume with one jack also grounded to the IEC (to provide a ground for the board). Then also ground the chassis to the IEC? The rest of the uninsulated components will then be grounded through the chassis.


Yes, ground the chassis to the IEC entry module, this is the most important connection in the amp as far as safety goes. I usually try to make the chassis ground stud also my signal ground, or run one wire between them.

Grounding one of your input jacks to the IEC module ground may set up a ground loop; if you have a scope you should check the hum level with the scope and a dummy load before connecting speakers. A scope also allows you an easy way to visually see the difference in hum level when moving ground wires around without the potential of frying a speaker.

If you do not have access to a scope, use a junk speaker for the first power up.

If you end up with excessive hum, you can also look into a ground-lift scheme using R's and C's.
 
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