ground-loop problems

[David Lesher]

Here, a standard circuit is 120v/20A or 2400 watts [at unity PF...]

Indeed. So one circuit should be adequate for feeding any 'portable'
appliances in a room? Excluding heating etc. Not many domestic audio
systems will need a 2400 watt supply. Not even mine. ;-)

You clearly don't know the folks I do...

32 amp is the standard these days.

Thanks to the EU...

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

The local transformer is on a pole outside, or a pad. The breaker panel
is split; half the loads on each leg. Big loads: stove, water heater,
whole house airconditioning, dryer are fed with 240V.

Why would you want 'three or four' 20 amp circuits in a 'family' room?

Why would anyone drive down the wrong side of the road, or use Whitworth
threads? It's not usual for a large room to have multiple circuits. If we
had a 7500 watt scheme, one would do, I suspect.

 

[David Lesher]

Is there a limit to the number of outlets on one circuit?

I don't know, but likely. Many building codes require outlets every
'n' feet, not crossing a doorway. A friend had a vestibule between the
house and garage:

<---7 ft -->
--=====-----
| |
x x
| |
--x--------

where x are doors, and === is a sliding door. To meet the
code, he had 5 outlets in the space. There's no furniture
but lots of places to plug in anything....

 

[Eeyore]

I'd like to thank everyone who took the time to respond to my question. I
was particularly appreciative of those that told me about noise & grounding
problems I've never even heard of.

I'm not quite ready to put everything on one circuit. So I'm going to call
both Parasound and Pioneer to see what insights, if any, they have to offer.

Again, thank you-all for your help.

PS: As for balanced cables being an OTT solution for home installations... I
have five power amps, four of which sit next to the speakers they drive.
Given the distances, and the fact that the amps draw significant current,
and some are on different circuits, it would not be a good idea to use
unbalanced cables.

I could tell you a thing or two about that as well. Balanced connections are
VERY advisable especially with the rise in use of SMPSs with their associated
ground leakage currents and the general increase in EMI pollution in the aether.

Graham

 

[William Sommerwerck]

Use an optical cable.

Oh? How? The system uses coax.

Does someone make an RF/optical, optical/RF converter?

 

[William Sommerwerck]

I did ask the sous-manager of the Bellevue Magnolia, and was told that

Er, either they're fitted with balanced connectors or they're not. To
modify an unbalanced unit isn't a trivial matter. Involves either using
expensive transformers at either end of the line or incorporating new
electronics. You don't just buy a new cable. ;-)

Sure you do. Almost all "good" home-cinema (as well as middle-to-high-end
audio) equipment has both balanced and unbalanced ins and outs. (My
Parasound controller does. I use the unbalanced outputs to feed a Pioneer
quadrascope.)

 

[William Sommerwerck]

I've Googled, and as far as I can tell, there is no commercially available
device that converts cable-TV RF signals to optical, then back again. What
would be the point of such a device, when an isolation transformer would be
much, much cheaper?

On the other hand, there are hundreds of products that convert TOSlink to
coax and back again.

 

[William Sommerwerck]

I've Googled, and as far as I can tell, there is no commercially
available

There is no reason. You can use a six hole Amidon core and make a
1:1 isolation transformer. Bytemark used to sell a lot of Amidon cores
and beads at hamfests, but their website has been gutted. I can't find
my Amidon Databook right now, but I'll see if I can locate it this
weekend.

You may find a suitable core in a junk two way 75 ohm TV splitter. The
Amidon website is useless, but the style would be like their
FB-61-5111-2.5, although type 64 core material would probably be better
than type 61. You can open a diecast splitter by shoving a sharp awl or
small screwdriver through the aluminum in one corner and peel the thin
aluminum back away from the conductive epoxy. If you can't find one, I
might still have some left from they 75 ohm return loss bridges I used
to build. They are out in the shop, and it's still raining around here,
so it will be a day or two before I can check for you.

Thank you for your suggestions and kind offer. I'd appreciate your looking.

When I was putting together this device *, I opened the balun with a F plug
on one end and two screws (for the twinlead) on the other. ** The thought of
"rolling my own" crossed my mind. The whole thing verges on the trivial, the
"hard" part being firmly and stably attaching the F jack.

Two obvious questions...

1. Any particular type of wire if I want to get to 1GHz or beyond? (One
would think litz wire would be appropriate and needed.) Or can I just
cannibalize what's there?

2. Ditto for the number of turns. Same or less than the number in the
existing unit?


* I actually invented it 25 years ago, to resolve the same problem, but
that's another story.

** The other balun has a F jack on one end, twinlead with terminations on
the other end.

 

[William Sommerwerck]

Total overkill. Balanced audio is only needed for very long runs or in
very hostile environments -- not found in the home. Are your aerial
and video connections balanced?

We've been through this before, and I'm not going to keep arguing. Most
equipment these days has balanced connections. It's ridiculous not to spend
a little more for balanced cables.

 

[William Sommerwerck]

Wow. Thanks for all that useful stuff. Really.

 

[cjt]

We've been through this before, and I'm not going to keep arguing. Most
equipment these days has balanced connections.

Domestic? It doesn't. It adds cost for no reason.

It's ridiculous not to spend a little more for balanced cables.

All a cable needs to do is connect things together. Properly. And you
simply don't need to use balanced in a domestic environment.
[/QUOTE]
It doesn't hurt. The incremental cost is small.