Another Tubelad SE build

[athos56]

I'm ready to wire up my Tubelab SE using 45's. Here are some pictures. The only question I have is for someone to ok my ground schema. RCA ground lugs, PCB Ground point, black speaker terminals, Transformer Case, all directly wired to the plug ground lug.

[aardvarkash10]

lots of good grounding advice here - grounding cable. The one I hadn't come across before but used in my latest build (6CM5 p-p) is to have the signal GROUND (all star connected) separated from the safety EARTH - with a 100 ohm 5w resistor connecting them. No hum issues in this build, and the B+ and heater (28VAC) trannies are up close and personal with the rest of the components in the case

[athos56]

Yeah but there is no metal in the chassis at all for a ground point other than the safety ground. Thanks for the link!

Looked at the link, I have successfully grounded many amps, all point to point in a metal chassis, this is the first wood chassis with a pcb hense the question (not really covered in the thread) Thanks though

[aardvarkash10]

one end of the 100 ohm resistor IS your star connection point. You have already identified the PCB's signal ground. Bond this to one end of the 100 ohm 5W resistor. Bring all the other signal grounds (but not the transformer case) you have to this point as well. Instant star ground point!

Now connect the other end of the resistor to your safety earth point. The transformer case should be EARTHED ie connected directly to the safety earth point, since it is not a signal path component and its earthing is an electrocution protection requirement.

Done!

[Geek]

Please tell me that outlet is a switched power output or the like and you don't attach power through a male-male cord

Love the wood chassis.

Cheers!

[aardvarkash10]

it sure is a good looker! Congratuations on that - it has a high WAF at this side of the world...

[athos56]

Originally Posted by aardvarkash10

one end of the 100 ohm resistor IS your star connection point. You have already identified the PCB's signal ground. Bond this to one end of the 100 ohm 5W resistor. Bring all the other signal grounds (but not the transformer case) you have to this point as well. Instant star ground point!

Now connect the other end of the resistor to your safety earth point. The transformer case should be EARTHED ie connected directly to the safety earth point, since it is not a signal path component and its earthing is an electrocution protection requirement.

Done!

OK, I totally get your point! Thanks for spelling it out for me.

Yeah that outlet is crazy Wanna see a picture of the nice male to male cord I made? I'll change it to a switched outlet or keep the cord separate from the amp or epoxy it in place, don't worry.

The chassis is a shadow box I got at a craft store, I knocked the glass front and cardboard back out and put a wood top in.

[athos56]

I used the grounding scheme suggested but used diodes (one going in each direction) in place of a resistor. This amp is the quietest of all my amps, both in terms of hum and power. Great highs and good bass, I used the 5k edcor GX opts. I think I'll buy some 2a3's for a tad bit more power.