Dedicated 20 amp lines/should i use a sub panel

Al, (almarg),

By chance have you been following the exchanges between noromance and me in response to this post of his?

noromance
904 posts                                                                                                 01-03-2018 10:23pm

I ran 2 x 20amp runs on 10 gauge from 2 side by side breakers for monoblocs. I ended up not using one of them because of a hum loop. Let us know how you get on.

Both mono block amps are floating the safety equipment ground.

When everything is fed from one dedicated circuit no hum.
When the other dedicated circuit is used to feed the other amp he gets the hum.
Is there a chance the hum is not caused by a difference of potential between the two equipment grounds of the two dedicated circuits?
Just a gut feeling I don’t think the equipment grounds are causing the hum.

And how would you explain this?

noromance
904 posts                                                                                                  01-04-2018 2:29pm

Jim,
8/2 with ground. You are correct about the legs. I also tried it on both legs. So instead of 22, 24, where I originally connected it, I had tried it on 23, 24 but it still hummed. In fact, as it’s a basement space, I just ran in a 12/2 on 15A breaker on the same leg to see if it still hummed with the (2 wire) monos. It did. But it doesn’t when I add my REL sub. So all is not lost! I should say that there is normally no hum from the rig.

But it doesn’t when I add my REL sub.

???

Any ideas? Suggestions?

How about if the mono amps are using an AC Line filter cap/s and maybe one or both is leaking to the chassis of the amp. What if the hot and neutral AC polarity is reversed on one amp with respect to the other?
https://systems.audiogon.com/systems/1593

Again, any ideas?

Jim

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