The measurements are good......
The bad news is it does not help the hum problem.
From the pictures you supplied of the sub panel what I could see the electrician you hired did a good job. The only code violation I could see was the (4) 30 amp breakers he installed for branch circuit protection instead of 20 amp breakers..... Just guessing he did what you probably requested.
At any rate that would not be causing your hum problem.
You seem to have isolated your hum problem.... The problem exists between the power amps and the speakers.
Could your problem be RFI/EMI on the AC mains of your home's electrical system? Well if you live in an area that is warm at the present time you could shut off every breaker in the main panel except the 2 pole breaker that feeds the sub panel. Then check the amps for the hum.
LOL, take a flashlight with you....
If the hum is gone then start turning back on the breakers one at a time until you find the source of the problem.
Still hum? Then, jmho, I would think that would rule out RFI/EMI noise, interference, on the mains. That is, at least from a source within your home. That does not mean EMI/RFI noise is not coming in from outside your home on the utility power.
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Maybe the problem is the power amps and the sensitivity of the speakers??
By chance do you have another pair of speakers you could try? Less efficient?
You might try a different pair of speaker cables. For a test just some cheapo Home Depot rip cord would do.
Sorry, I am out of ideas......
I did send an email to an EE who posts here on Agon. I asked him to read the thread and post a response if he has any ideas.
Jim
The bad news is it does not help the hum problem.
From the pictures you supplied of the sub panel what I could see the electrician you hired did a good job. The only code violation I could see was the (4) 30 amp breakers he installed for branch circuit protection instead of 20 amp breakers..... Just guessing he did what you probably requested.
At any rate that would not be causing your hum problem.
You seem to have isolated your hum problem.... The problem exists between the power amps and the speakers.
Could your problem be RFI/EMI on the AC mains of your home's electrical system? Well if you live in an area that is warm at the present time you could shut off every breaker in the main panel except the 2 pole breaker that feeds the sub panel. Then check the amps for the hum.
LOL, take a flashlight with you....
If the hum is gone then start turning back on the breakers one at a time until you find the source of the problem.
Still hum? Then, jmho, I would think that would rule out RFI/EMI noise, interference, on the mains. That is, at least from a source within your home. That does not mean EMI/RFI noise is not coming in from outside your home on the utility power.
==========================
Maybe the problem is the power amps and the sensitivity of the speakers??
By chance do you have another pair of speakers you could try? Less efficient?
You might try a different pair of speaker cables. For a test just some cheapo Home Depot rip cord would do.
Sorry, I am out of ideas......
I did send an email to an EE who posts here on Agon. I asked him to read the thread and post a response if he has any ideas.
Jim