persistent 60 cycle hum only on tube gear

Erik,

Your exlanation is one of the best I’ve seen, and you are performing a great service to the community.  On my power cable page I warn people about defeating the ground on any power cables in their system.  I’ve yet to cover isoalted grounds.

In any case, I’m putting a link to your blog post on that page.

Cheers,

Thom @ Galibier Design

Great post @erik_squires , thank you.

@yesiam_a_pirate 

I suggest you watch this You Tube video on the Puritan Audio Laboratories GroundMaster.

Note: He says, Do not defeat the AC mains safety equipment ground.

Note: His mention of installing a Supplementary Ground Rod. This Is Not an Isolated Ground Rod. A Supplementary Ground Rod must be connected directly to the branch circuit EGC (Equipment Grounding Conductor) per NEC code for electrical safety. He should of mentioned that in the video.

For the Ground Master you can connect an additional ground wire from the ground rod to the Ground Master. One ground wire to the AC mains EGC connection in the wall outlet box. One for the Ground Master. 

https://www.youtube.com/watch?v=2G8-Z3BMDcw

FYI, "Supplementary" Ground Rod, is an old name used years ago replaced by,  "Auxiliary" Grounding Electrodes. Therein Auxiliary ground rod.

(NEC, 250.54)

If you must, use a ground cheater on the power cord(s) of the equipment to lift the ground from the chassis. (Not recommended for electrical safety though.) 

Hopefully @atmasphere will look at the schematic wiring diagrams I provided in my above post for your ARC equipment. 

@atmasphere said:

Does the amp make a buzz or hum without the preamp connected?

If yes, Is it both channels or just one?

If neither channel, The amp is OK.

You need to do this test. If you still have a buzz or hum with just the amp, (ICs not connected to inputs), 

You may need to use shorting plugs on the R & L inputs.

Still have buzz, hum? Try moving all the digital streaming equipment away from the amp and unplug it from the AC main oulet for the test.  

Read @bruce19 above post.

.

Note: It appears the circuit signal ground is connected solidly, directly, to the EGC grounded chassis. (Not good). Therein, signal ground is not connected, (for example), to a 10 ohm resistor then to the grounded chassis. 

@jea48 The audio input is grounded to circuit ground, not chassis. Normally in a balanced circuit the chassis and audio ground can be the same thing, but since this amp and a lot of high end preamplifiers (such as ARC preamps) do not support the balanced line standards, the practice of separating the two is a good idea. 

At any rate, until we hear back from the OP, the rest is speculation.

FWIW many claim to eliminate any system hum after introducing the Vinshine/Kinky Studios TaiHang power conditioner.