Interesting idea, but that probably will not fix it. It's about how the devices are AC grounded.Originally Posted by BMWCCA
I'll just plug everything in there and run an extension cord downstairs!
Do the "back from the woofer" test we talked about above, and see if you can determine which device is producing the hum. Or, just leave the AC ground floating on that one amp and don't tell anyone! :shock:
It would be useful to measure the ohms from the mains plug earth prong to the earth signal (input or output( of both amps, the crossover and other sources feeding the crossover.
One or more of them is a short between those two points.
Ultimately if you do not have proper chassis too earth grounding from chassis could well be floating above ground and no longer act as a shield from the signal electronics.
Therefore you have several issues to address.
It would be best to obtain a quote from a qualified electrician to install a dedicated mains outlet for your equipment.
You also need to have a technician test/modify all your equipment to reduce or eliminate the apparent earthing problems.
Otherwise frankly you are walking all over yourself or you may suffer a fatal accident which I should point out we are not responsible for.
This is really beyond the scope of the forums as you need on site qualified technical assistance.
Until someone is deadThe statistics (deaths) from incorrectly wired appliances is quite alarming.
If there is a cause for an insurance claim a coroners report or something like that you will not be covered and you should consider your home insurance and life policy cancelled as soon as you disconnect chassis earth (they cover civil/legal liability but not deliberate acts of stupidity that cause harm)
Until someone is dead
If there is a cause for an insurance claim a coroners report or something like that you will not be covered and you should consider your home insurance and life policy cancelled as soon as you disconnect chassis earth (they cover civil/legal liability but not deliberate acts of stupidity that cause harm)
Once more: The house is over sixty-years-old. The living-room wiring is two-conductor copper wire insulated in rubber covered with braided cotton. It's old! The only outlets that test properly are those I replaced in the upstairs when I had all the wall-board off the studs, and the basement outlets which are wired with exposed BX cable (armored coiled metal). The downstairs is all plaster. Even though the outlet getting all the attention is almost directly above the basement and the breaker panel, the path through hardwood, plaster, and diagonal sub-floor is not a direct one and I don't really feel like ripping out wallpaper, plaster, and flooring to run a ground right now. I haven't seen a two-prong outlet in a store for decades. Most likely why this one is a grounding outlet with no ground wire.
I appreciate the concern for my safety, if that's what it is, but I'm reasonably certain my insurance company is aware of the situation since we've been in the house for 25 years and have had the same insurance company the whole time. The fire department is less than five miles away but I'll alert them to check whenever they ride by to see if we're still alive.
The nearest fire hydrant, however, is over two-miles away, which may have been a problem when our neighbor's house (Stefan Lessard, bass player for the Dave Mathews Band) burned down two years ago. The cause of the fire was never determined but I'm sure it must have been that new-fangled electrical service with the extra third wire since his house was only four-years-old at the time of the fire!
Can't you run a dedicated earth ground wire from just the power strip your gear is connected to? A small hole in the floor wouldn't be too intrusive, drive a ground rod and hook the wire to it.
I admit I'm not much of a home electrician, but I was pleasantly surprised that my old house (mostly) checked out with the diagnostics plug shown a few pages back. The outlet my computer is plugged into had no ground, so I ran an earth ground for it, and the computer is hooked to my stereo which has a grounded outlet and I get no hum through all those various components. So I count myself lucky there.
The outlet tester shows "good" as long as the pre-amp is plugged into the outlet. With nothing in the outlet it shows open ground, as expected with a two-wire service. I'll try slipping a ground wire through the cable hole and to the panel ground or the BX armor. That's where they grounded the phone line network-interface-device. I may have some well-pump wiring left from that last lightning strike.
I'm also planning Bo's component diagnostic from speakers-back. But work comes first, for some reason.
That tells the whole story. You have to fix it.
Widget
Let me clarify: The outlet tester shows an open ground at that outlet with nothing plugged in. Shutting off the breaker and pulling the outlet confirms it has original 2-wire house wiring. But . . .
Chalk up ten points for Bo. Moving backward from the speakers showed a problem at the new phono plugs at the small Crown. Pulling them out got rig of the hum and simply wiggling them when plugged in got rid of it, too. No time today to go in and find out what's up but repositioning them got rid of all hum with no lifted grounds. Obviously, as Bo had continued to suggest, the house wiring wasn't the issue.
And—just so Ian can sleep tonight—no grounds have been lifted. Unless you consider the fact that that entire house circuit isn't grounded at all!
Thanks again.
The dynamics of Bill Evans' Quintessence seemed like a good test. Nice quiet passages. Certainly horns-on-horns is very cool but let us not discount the subtle presence of Ray Brown's acoustic bass over a 2245H even at low volume. The 4345s continue to sound wonderful. No hum, no shocks, no animals were harmed so far in this installation. And yes, I'll pull the Crown eventually to see what's up. I've got one spare D150A-II loaned out to a neighbor but there's at least one more PS-200 still sitting in its box somewhere. It's so easy to lose count!
Guess I'll stash this back in the electrical drawer!
As expected...
You used the cheater to make the test right? If someone has replaced your original 2 wire outlet with a three wire outlet that is really wrong and very dangerous.
So you aren't going to ground your system??? You should fix it.
You should never plug a three prong device into a two wire circuit. I found out the hard way... no fire, no death, but it dropped me on my ass. The chassis of any of your three wired equipment could become lethal under certain circumstances.
Widget
Again, I appreciate the concern for my welfare, if that's what it is. I'm not taking quotes from contractors and I'm not doing electrical work without a license. Even if the only outlets that actually test out as proper are those I installed in the upstairs. When the time comes to punch a hole in the plaster and the floor, someone competent will be doing the work. Somehow we'll manage to get along as we are, and as we have for the past 25 years. While all the new houses around us burn down under suspicious circumstances!
The receptacle box is nailed to a wood stud and has two wires going to it. Even if I "grounded" the adapter to the face-plate screw there'd be an open ground. Last time I looked you couldn't even buy a two-conductor duplex outlet at our local Lowe's store. I realize the old system offers no protection against electrocution. I also realize if I drive my car fast I might get into an accident and kill myself. I prefer to drive fast cars fast.
In the words of Monty Python, "I ain't dead yet!" Amazing any of us ever lived to the ripe old age we have, isn't it?
I'm going back to enjoying the music now! Thanks again.
Whatever...
Outstanding!!!I'm going back to enjoying the music now! Thanks again.
Let's call this thread done and close it then.
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