New space, Amps all hum now?

Was suggested by the tech guy at the college to replace the power cords to the amps with non grounded ones?

NEVER a good idea. Back in the old days, amps didn't even have grounded cables. And had a polarity switch because the 2-pronged plugs were not defined as + and - like today's cords are. Could it remove the hum? Yes. Could it give you a bad shock? Yes.
 
NEVER a good idea. Back in the old days, amps didn't even have grounded cables. And had a polarity switch because the 2-pronged plugs were not defined as + and - like today's cords are. Could it remove the hum? Yes. Could it give you a bad shock? Yes.


Go find an axe handle and go and beat him to death with it. NEVER remove power earths!

Dave.

My thoughts exactly.
 
Was suggested by the tech guy at the college to replace the power cords to the amps with non grounded ones?

So he dislikes you? Or he is after your girlfriend?

Don't do it. However I suspect the hum problem is being caused by bad earthing on the power supply.

Alan
 
So he dislikes you? Or he is after your girlfriend?

Don't do it. However I suspect the hum problem is being caused by bad earthing on the power supply.

Alan

What happens when you run just ONE amplifier and rotate it in the horizizontal plane PLEASE!

The only way this is going to get fixed (IF it can be) is to take a very systematic approach.

Dave.
 
What happens when you run just ONE amplifier and rotate it in the horizizontal plane PLEASE!

The only way this is going to get fixed (IF it can be) is to take a very systematic approach.

Dave.

Hum is there whether the amps are on singly or together, whether rotated, stood on end or moved around in the room. Even plugging them into the other circuit now has hum. I'm landing on the water meter or router, so perhaps no real fix other than to play louder and edit/mix guitar tracks carefully.

Really appreciate all the info here.
-Bob
 
Hum is there whether the amps are on singly or together, whether rotated, stood on end or moved around in the room. Even plugging them into the other circuit now has hum. I'm landing on the water meter or router, so perhaps no real fix other than to play louder and edit/mix guitar tracks carefully.

Really appreciate all the info here.
-Bob

Ok Bob well my only conclusion is that you have a bad, i.e. high resistance mains earth or possibly none at all!

Dave.
 
Hum is there whether the amps are on singly or together, whether rotated, stood on end or moved around in the room. Even plugging them into the other circuit now has hum. I'm landing on the water meter or router, so perhaps no real fix other than to play louder and edit/mix guitar tracks carefully.

Really appreciate all the info here.
-Bob

As I mentioned previously...you could unplug the router for a few minutes to see see if that's the issue. Easy trouble shooting step. I also mentioned that here in south Florida we did have a problem with some water meters causing interference after being converted from analog to digital. It was in the news for a short while a few years ago. I don't recall the exact cure but I think it had to do with some sort of isolation or shielding or both.
 
If both amps have this hum now that you have moved them, perhaps there is something nearby producing a magnetic field which gives your amps the new hum. You didn't say that it was a 60Hz hum, but that frequency is the most common stray hum in America. Two questions come to my mind: (1) is there a high-powered motor such as an A/C compressor, large blower, or the like which produces a magnetic field in your new location? (2) Is the hum's volume related to the setting of the level controls on the amps? What I am driving at on Question 2 is whether the hum is being introduced through something connected to the amp or whether it is there with the gain down and maybe, if not too difficult, with all input devices disconnected. It sounds like there is either a ground loop somewhere or else the hum is being introduced magnetically somehow from a high-current source somewhere nearby. I would think that new wiring and a new breaker system would be "clean," but don't overlook at least the remote possibility that someone didn't get things grounded well. This one is very rare; but we cannot forget that occasionally even professional workers goof up, though they certainly shouldn't do so. I know of at least one case years ago when a new pipe organ was being installed in an auditorium, and the blower circuit was wired by a professional, and probably a union, electrician; but when the pipe-organ technician came in to power up the instrument, the blower did not come on. It seems the electrician forgot to tie the 220VAC wiring into the main panel! Imagine that! You'd have thought the fellow would have checked for power all the way out to the endpoint specified in his contract. So mistakes definitely do happen, though I would think this one might be the least-likely source of your hum - namely a poor electrical ground.
.
 
A BAD SHOCK! YOU BET! I wouldn't dare replace a grounded cord with a nongrounding cord! While I was attending an amateur musical program one evening, a couple of fellows set up their two amps and guitars to play and sing a song. When the lead singer grabbed the mike stand of the mike belonging to the house as one might casually do, he was shocked so badly that he fell off the little stage. That was in the era when amps didn't have the grounded cords; for one thing, if a short developed between the chassis of the amp and one side of the AC line cord, then you have a 50/50 chance of the chassis sitting 120 volts above ground. In those days, there could be a shocking voltage between two guitars on separate amps or as in the case I knew between the guitar and the house mike, which was probably well grounded while the amp for the guitar was not. We should never defeat the polarized plugs on line cords or on those cords with a third wire as a ground.
 
"Bad earthing on the power supply...." If the hum didn't occur in the original location, but now it does, I wouldn't suspect the power supply in the amp(s). With the same hum in both amps, I would have to suspect something outside of both amps, since it is not too likely that you would find the same hum-producing in both of the amps.

Something "weird" just occurred to me: I note that you moved the amps downstairs to a quieter location. Of course, I don't know how bad the hum is, but could it be that at least some level of hum was present in your original location, then when you moved the amps to the quiet location, you now hear that hum? I know that was a strange consideration; but when we are troubleshooting a difficult problem, we should consider at least briefly all the possibilities of which we can think.
 
Lots of good ideas here. In Radio studios and even those apartment studios the ground was done through a 6 foot copper rod sunk into the ground.

I myself would start by disconnecting the input that eliminates the hum coming into the amps- if no hum then it is getting into your input signal path.
OLD houses can have different ground potentials and this due to clamping on electrical pipes that has gone bad will make ground loops. I forget the wall ground and make a star pattern ground on chassis with thick wire. This way if a wall ground is floating it will be grounded through the star pattern.

Running audio cable that is not 100% shielded will allow all kinds of interference into the signal line. The question is why are you using this kind of cable if you
want a good result- that spiral wound drain wire 50 cent cables should be eliminated in all cases. Throw it out.
Some of the test bench connections I have made using RG6 3GHz coax- it is also low capacitance or it would never handle 3GHz. The low cap and 100% shield is what I am after.
I use to buy cable4less 6 foot ones but they stopped carrying them. I think Monoprice cables are the next cheapest BUT good cables to get- I look for those that can carry 50KHz without loosing more than 2 dB as measured by my equipment. The Cables for less cables did meet that spec. I found out by cutting one they are not coax but more like Canare cable with two conductors in them but shielded well.
 
Lots of good ideas here. In Radio studios and even those apartment studios the ground was done through a 6 foot copper rod sunk into the ground.

I myself would start by disconnecting the input that eliminates the hum coming into the amps- if no hum then it is getting into your input signal path.
OLD houses can have different ground potentials and this due to clamping on electrical pipes that has gone bad will make ground loops. I forget the wall ground and make a star pattern ground on chassis with thick wire. This way if a wall ground is floating it will be grounded through the star pattern.

Running audio cable that is not 100% shielded will allow all kinds of interference into the signal line. The question is why are you using this kind of cable if you
want a good result- that spiral wound drain wire 50 cent cables should be eliminated in all cases. Throw it out.
Some of the test bench connections I have made using RG6 3GHz coax- it is also low capacitance or it would never handle 3GHz. The low cap and 100% shield is what I am after.
I use to buy cable4less 6 foot ones but they stopped carrying them. I think Monoprice cables are the next cheapest BUT good cables to get- I look for those that can carry 50KHz without loosing more than 2 dB as measured by my equipment. The Cables for less cables did meet that spec. I found out by cutting one they are not coax but more like Canare cable with two conductors in them but shielded well.

While all good suggestions, the OP has already said that he has a professional electrician doing all of the wiring. He also just recently added this area's own ground connection. We should hope this electrician knows his craft.
 
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I do want to make one point, since you are now thinking of just living with the hum. That might be out of disgust or humor, but either way, don't do it. There is a solution to this. BUT, you really have to look at it from the beginning.

We're now hearing there is a new router? That wasn't in the original post. What we heard was everything was the same, just at the other end of the house. True, the water heater could be an issue. I don't have that, because mine is 30 feet in front of the house, at the street. Sorry, my own version of humor.
 
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I seem to have got it down to the router or water meter, will be doing some investigations tomorrow, when my wife is out all day and the internet can be down for a while.
 
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