Equi=Core Hum & Other Issues

@jea48  Thanks for the transformer wiring info.
I'd like to keep you updated if you don't mind. Electrician appt. is Tuesday; my service order states to inspect panel and subpanel, replace the subpanel breaker, and inspect/service the Equi=Core.

I pulled the EQ out of service and will pop the top this weekend. I have a Brick Wall passive conditioner in the circuit running digital devices, no issues.
But now I'm hearing hum from the power transformer in my Atma-sphere amp. It uses the second dedicated circuit from subpanel with my preamp. I'll have to check with Ralph, the amp is supposed to have a DC blocker built in. Preamp is Audio Note using their large EI transformer.

This leads me to the question; can DC offset be measured by the electrician either at the service panel or the wall receptacles?

@grannyring , made an appt. with the electrician.
This device is highly thought of on the forums...
https://avahifi.com/products/humdinger-dc-line-blocker

Will the very large toroid in the Equi=Core 1800 be a problem for a small device such as this?

Lowrider57 said:

This leads me to the question; can DC offset be measured by the electrician either at the service panel or the wall receptacles?

DC on the AC mains can be measured at either location. In your instance you want to measure it at the wall receptacle outlet that you are using for your audio equipment.
Question is does the electrician and or electrical contractor you have hired have the test equipment to properly measure for DC voltage on the 120Vac mains. Unless the electrical contractor/electrician has a power quality analyzer meter something like this one then the answer no.
https://www.fluke.com/en-us/product/electrical-testing/power-quality/437-series-ii#

A typical good quality digital multimeter (DMM) will not correctly measure for DC on the AC mains unless a low pass filter (lps) is used. The lps is connected between the 120Vac mains and the DMM. The DMM is set to auto DC Mv.
I have a FLUKE 87 DMM and it cannot correctly measure for DC on the AC mains. I made a simple lps. Nothing to it. It’s of a lot cheaper than buying a power quality analyzer meter.

I don’t know how big the electrical contractor/electrician is that you have hired.
I do know a few good sized electrical contractors in my area. They could easily afford to buy a $10,000 power quality analyzer meter. I doubt if any one of them has one setting on a self in the shop just setting there waiting for the next time it will be needed.

If they have a customer where they may have a power quality problem in their facility the electrical contractor hires a Power Quality Testing Company. For around $150 to $200 an hour you can hire a Power Quality Testing Company that employs qualified, certified, trained, technicians to preform the power quality testing. The testing company furnishes the electrical contractor a complete certified test report when they are finished.

Do you need to hire a Power Quality Testing Company? Probably not.
I do find it odd though that the transformer in the Atma-sphere power amp is mechanically vibrating more than it normally should. It’s my understanding Ralph installs a DC blocker in all his amps that use a Toroid power transformer.

Quick test. Check/measure the AC line voltage at the duplex receptacle wall outlet with the power amp turned on. You want a conned load for the test.... A higher than normal AC voltage can cause a power transformer to buzz, mechanically vibrate, louder than normal. Normal? Voltage should be around 120V.123Vac is getting on the high side. 124Vac -125Vac and higher is definitely on the high side.... Look on the rear panel on the amp, what is the recommend nominal AC line voltage for the amp?

Jim

Correction:
Low Pass Filter (LPF).
NOT lps.

.

There are many DC blockers available, at different price points.  PS Audio used to make a popular one, occasionally available used.  Audio by Van Alstine, Emotiva, and Isotek all have models.