Dedicated 20 amp lines/should i use a sub panel

When I did my Listening room installation, I moved most the rest of the house circuits to a separate sub-panel - but I needed the space breaker wise.  If  you don't need the space just use your existing panel, but have your electrician tighten up all connections.

I ran 12/2 to the outlets but the longest run is only 20 feet of wire,  I have 9 dedicated lines, one leg of the incoming power is used for the tubed system,  4 circuits.  The other is for my SS system,  5 circuits including a 220V one.

I don't get caught up in the Outlet craze - use Leviton Industrial grade outlets.

Running separate dedicated lines will be the single most $ efficient upgrade to your system you can do, the second one will be room treatments.

Good Listening

Peter

Looks like I should expedite my plan to rewire the power cords on the power amps with new OFC cables including connecting the safety ground. I’ve been meaning to do it after changing the power cord on the preamp with very positive results. Thank you.

noromance
906 posts 01-04-2018 11:20pm

Looks like I should expedite my plan to rewire the power cords on the power amps with new OFC cables including connecting the safety ground. I’ve been meaning to do it after changing the power cord on the preamp with very positive results. Thank you.

@ noromance,

Is this the schematic wiring diagram for your amps?
http://www.freeinfosociety.com/electronics/schematics/audio/pictures/eicohf22.gif

If so, see that C13 (.03 600V) cap connected to the AC line that is connected to the chassis? (Just to the right of the AC line fuse). That would have to be removed before connecting an equipment ground wire to the chassis.

That’s the cap I was attempting to ask Al about in my previous post. I forgot it was/is referred to as a "death cap". (Thanks imhififan for the 2 Links above.)
I always wondered why the cap was installed on the fuse AC line and not on the non fused line. With the old original non polarized plug the user had a 50/50 chance of plugging the plug into the wall outlet and getting the neutral, (The Grounded Conductor), the line the cap is connected to. Again note the fuse would be connected to the neutral line.
I guess back in those days electrical safety was seen different than it was in later years.
One example, old Knob and Tube wiring the HOT was ran directly to the ceiling light and the neutral ran through the switch on the wall.


The amps, at the time they were designed and built, were not designed to be directly connected to an equipment ground. You will be connecting the amplifier’s circuit ground/signal ground directly to the mains safety equipment ground. I am not sure if that will improve the SQ of the amps or harm it. Someone like Al or Ralph would need to chime in with their thoughts.

Jim

Thanks for your thoughts and questions, Jim.  Generally speaking a direct connection between AC safety ground and signal/circuit ground is an invitation to ground loop issues (both hum and high frequency buzz).  In good modern designs the two grounds are often connected to each other through a resistor having a resistance in the area of 10 to 100 ohms, which would probably be impractical to do in this case since chassis is used as signal/circuit ground in many places.  It would also stand a good chance of being sonically undesirable, due to the small impedances it might create between grounds at different circuit points within the amp.  So I would recommend that Noromance leave well enough alone, and if he chooses to upgrade the power cords on the amps that he **not** connect AC safety ground within them.

Also, regarding the "death cap" (and thanks to Imhififan for providing the good reference), it's worth noting in the photo of the underside of Nomance's amp that the cap has been replaced with a modern one.  So presumably leakage within that cap is not an issue.

But it doesn’t [hum] when I add my REL sub.

Noromance, what model is the sub, and if you are using the high-level Speakon connection what is the black wire connected to?

Also, if you want to pursue the hum issue further what you might try would be connecting each amp to its own dedicated line, with the two lines on the same AC leg, and then trying all four combinations of the orientations of their AC plugs. If the plugs are polarized or are 3-prong types, even though the safety ground is not used within the amps, for experimental purposes you could try that using cheater plugs.

Regards,
-- Al