[jea48]

Thanks for all the input. Just some background info on the basics.
-Everything is plugged into the same outlet
-The exact combinations of preamps and amp are silent at a friend's house
-all outlets are properly wired
-yes it is a 60hz hum
-I have tried a preamp with no ground and a captive cord as well as another preamp with a grounded cord...makes no difference in the hum
   I actually had an electrician that has done work for local recording studios come out yesterday and even he is befuddled. The only things he came up with were that the ground rod is corroded outside the house and he thinks the contact from the grounding wire is poor. He will replace that. Also, one of the electrical panels is inside the room and he thinks there many be some noise being induced by the proximity of the panel. He's the 3rd electrician and it doesn't seem to matter which amp and preamp I put in the system. Even matching preamp and amp from the same manufacturer causes the issue (with shielded IC's and various power cords)

Do you have an AC volt meter/multimeter?

Is this still your current system?

 schw06's system, a Two-channel Audio System by schw06Room Size 17x24x10
System Overview
Room Description
17 x 24 x 10 feet
Acoustic Treatment
GIK Acoustics diffusion
Components
Digital Source
Lampizator L4 Gen 4.5 with Duelund caps and volume control
Preamp
Melody Pure Black 101
Power Amp
Thor Audio TPA-60 monoblocks
Speakers
Meadowlark Audio Shearwater Hot Rods until Intuitive Designs latest creation is delivered.
Interconnects
Dale Pitcher designs
Power Cables
Abbingdon Music Research
Racking
Sistrum
Power Cond
PI Audio group Uberbuss


-Everything is plugged into the same outlet
-The exact combinations of preamps and amp are silent at a friend's house
-all outlets are properly wired
-yes it is a 60hz hum


Exactly what all do you take over to your friends house?
Just the preamp and power amp?
How about the power cords for the two units?
How about the ICs used to connect the preamp to the power amp?
I doubt you take the speakers with you.
Power cords would be a must. They appear to be after market. It is possible the AC polarity could be crossed in one of them.

If we rule out a ground loop. Just curious did you try a ground cheater/s to lift the safety equipment ground for a test?
If the hum/buzz is not heard through the speakers when nothing is connected to the inputs of the amp and the equipment grounds to the equipment are lifted when the preamp is connected to the amp and the hum/buzz is heard, I have a problem with the problem being the AC power at the wall outlet back to the electrical service. I am not saying the problem is not from the wall receptacle to the equipment.   

 He's the 3rd electrician and it doesn't seem to matter which amp and preamp I put in the system. Even matching preamp and amp from the same manufacturer causes the issue (with shielded IC's and various power cords)

The speakers are always the same, yes?

The only things he came up with were that the ground rod is corroded outside the house and he thinks the contact from the grounding wire is poor. He will replace that.
 

Important for lightning protection. I doubt that will solve your problem.
Does the electrician have a power analyzer he can connect to the mains power?
That would tell him if you have an AC power quality problem.

How old is your home?
Electrical, service?
Electrical Panels, is there one on the outside of the house and one on the inside of the house?

 

[sfox7076]

I think the amp he has has remained constant in the system.  I would ask him to confirm that though. 

[schw06]

Do you have an AC volt meter/multimeter?

Is this still your current system?

 schw06's system, a Two-channel Audio System by schw06Room Size 17x24x10
System Overview
Room Description
17 x 24 x 10 feet
Acoustic Treatment
GIK Acoustics diffusion
Components
Digital Source
Lampizator L4 Gen 4.5 with Duelund caps and volume control
Preamp
Melody Pure Black 101
Power Amp
Thor Audio TPA-60 monoblocks
Speakers
Meadowlark Audio Shearwater Hot Rods until Intuitive Designs latest creation is delivered.
Interconnects
Dale Pitcher designs
Power Cables
Abbingdon Music Research
Racking
Sistrum
Power Cond
PI Audio group Uberbuss


-Everything is plugged into the same outlet
-The exact combinations of preamps and amp are silent at a friend's house
-all outlets are properly wired
-yes it is a 60hz hum


Exactly what all do you take over to your friends house?
Just the preamp and power amp?
How about the power cords for the two units?
How about the ICs used to connect the preamp to the power amp?
I doubt you take the speakers with you.
Power cords would be a must. They appear to be after market. It is possible the AC polarity could be crossed in one of them.

If we rule out a ground loop. Just curious did you try a ground cheater/s to lift the safety equipment ground for a test?
If the hum/buzz is not heard through the speakers when nothing is connected to the inputs of the amp and the equipment grounds to the equipment are lifted when the preamp is connected to the amp and the hum/buzz is heard, I have a problem with the problem being the AC power at the wall outlet back to the electrical service. I am not saying the problem is not from the wall receptacle to the equipment.   

 He's the 3rd electrician and it doesn't seem to matter which amp and preamp I put in the system. Even matching preamp and amp from the same manufacturer causes the issue (with shielded IC's and various power cords)

The speakers are always the same, yes?

The only things he came up with were that the ground rod is corroded outside the house and he thinks the contact from the grounding wire is poor. He will replace that.
 

Important for lightning protection. I doubt that will solve your problem.
Does the electrician have a power analyzer he can connect to the mains power?
That would tell him if you have an AC power quality problem.

How old is your home?
Electrical, service?
Electrical Panels, is there one on the outside of the house and one on the inside of the house?

 

   My system is different now. Different everything including speakers and it seems to be independent of whatever power cables I use (including stock shielded) and I have tried many to solve the issue (both IC's and PC's). The problem appears to be independent of whatever equipment I use in the system. I do have a voltmeter and will try your suggestion later today. Again thank you for the input.
David

[schw06]

I think the amp he has has remained constant in the system.  I would ask him to confirm that though.

Nope. Not been constant. To make sure everyone realizes there is not a single component that has remained constant over the years. Only the hum

[avahifi]

Sorry for my misinformation regarding running the power amp with open inputs.

AVA amplifiers do not care if they are run with either open inputs or shorted inputs, they are quiet and stable either way.

I did not consider that other designs might have difficulties with being energized with open inputs.  Thus Roger's advice is correct with any except AVA amplifiers.  Test the amplifier alone with shorting plugs in its input jacks.

Frank Van Alstine

PS: Do you have any dimmer switches in the room where your equipment operates?  These are an excellent hum source, as are aquarium pumps and water bed heaters and high intensity lamps.

[Wayner]

I have an FM tuner, that when turned on, will make my systems hum, because the transformer in the FM tuner is poorly designed/poorly shielded. I too, was fighting a hum issue, thinking it was caused by dirty AC or poor interconnects or something else related to a ground loop.

The answer was distance. Moving the FM tuner away from the amp and preamp solved the problem. The tuner's transformer was creating a larger then normal magnetic field, and that field penetrated my preamp and induced hum. This may be the cause of the hum for you. Perhaps your amplifier's transformer is affecting your preamp, or your preamp's transformer is affecting your power amp.

My suggestion is to separate the 2 much farther then you have them now, even if that means using a 2 meter (or longer) interconnect to accomplish this. I have a semi-high degree of confidence that your hum is caused by EMF.

[schw06]

Wayner,
   You are my hero! After several years of this quagmire, it has been solved. Moving my amp as far away from the preamp, and as far away from the outlets and electric panel has solved the issue! This has escaped 3 electricians, countless audiophiles, and tens of hours with me getting increasingly frustrated. THANK YOU!!!!!!!!!!!!!!!!! When surveying the landscape I realize that there is essentially an equilateral triangle with the 2 base corners representing my 2 electrical panels in the home and the apex represents a confluence of 3 separate circuits converging at that point. Whether or not moving the components out of that is the reason for solution, I'm thoroughly relieved. Thank you all for your help! Special thanks to Wayner of course but again also for Dave E, Tom S, Frank V A, Roger M, and everyone else that I've not had the pleasure of meeting in person or via telephone conversations. I'm indebted to you all.
David

[avahifi]

Nice work there Wayne!

Frank

[dBe]

Nice work there Wayne!

Frank

+1

 

Dave

[Wayner]

I learned a lot of things from Frank, but also from one of my past employers, HTI. At HTI we make the suspensions for the hard disc drive industry. This device is the "tonearm" for the hard disc drive that has the reader head mounted to it. It is currently held at 4 millionths of an inch from the disc surface.

This suspension has a flex circuit on it that delivers the information from the hard disc drive to the computer and during the manufacturing process, we have built machines that measure the capacitance of these traces. Those values are in nano-farads. We had nothing but noise problems. Then I realized that we had a machine with 3 power inputs (because it was a huge machine with many modules within it). The cure, which I discovered, was to have only one ground to the system. We also discovered that there were offending components that produced EMI, and had to be moved away from earth ground and other very sensitive components. This is the reason why I suggested the move.

Thank you Frank, and others and I am glad the cure has worked. It doesn't always work out this way!!!!!!

[TomS]

Awesome news David