I can't speak to what others were looking for but it is possible for a speaker cable to pickup noise, esp. in a place like NYC. But if you swapped speaker cables and the same hum came out of the right speaker than that isn't the issue. I'll stick with my suggestion this is a problem for Steve.

P.S. Nice looking system

The left side hums more? Have you tried unplugging those grow lights? I have overhead LED lights on a dimmer, off is not a problem but when the are on I can hear a distinct hum. My system is on its own circuit, I keep the lights off.

RY,
Just one more thing to try!
Please try another electrical circuit, just one more variable to test.

Just some thoughts from your setup picture. Is the grid work in the window made of metal? Is that a hot water/steam cast iron radiator under the window? The orientation of your amp appears that the left channel tube is closet to the window? Maybe turning the amp 90 degrees might balance the hum. The window grid acting as an antenna if metal. Cast iron radiator is a huge ground drain. Maybe the open crossover is interacting with the window/radiator. Have you tried the crossover or speaker in a different location? Maybe try running a chassis ground wire from the amp to the radiator. My thoughts and good luck!

Hello all,

I super appreciate your insight and advice...

Some updates:

-The hum is still louder on the left channel of the amp. (I swapped L-R speaker cables and the louder hum switched to my right channel, so seems internal to the amp). HOWEVER, it seems to have been reduced in DB. It is no 50db Left, 41 db Right. (before it was 50db Left, 44 db Right after multiple measurements).

-My wifi router is 2' to the left of my amp. I tried unplugging it and taking measurements at night, but the hum remained unchanged.


CURIOUS... I am curious if I should just live with this degree of Hum. If you have the "Sonic Tools" app, could one of you measure the hum an inch in front of your speakers? I am using a new iPhone... Should I live with a 50db hum on one channel?

In my correspondence with Steve, he said the hum should be the same on both channels. Should I send it in given it is clearly and consistently louder on the left channel?

Thanks for advice.
Richard

I am still putting together the picture.

So new observations:

-Recently, the hum seems to. have gone from 55db L / 46db R to 50L/45R. The hum on the Left Channel is quieter?

-I noticed when remeasuring today, the Left Channel is actually 120hz. The right channel alternates between 120hz and 62hz.

I think that seems significant. What do you all think?

I will soon diagnose the following:
-moving amp location completely, rotating it 180 degrees
-turning off all circuits in the house except the dedicated curcuit that the amp is on

....

appreciate the advice and insight... hoping to resolve this without the 1K to reinstate the lifetime warrantee, and don't want to live without this beautiful sound for the 1-2 months it may take to send it in to be diagnosed...

thanks!
Richard

So interesting… and SOME PROGRESS!

… SO… I was restocking to add some vibration absorption below my rack, and I took the opportunity to experiment with the hum issue.

First: I unplugged all of my components besides my amp. I unplugged all inputs. The hum continued.

Next: I moved my amp to the middle my room, and reconnected my speakers. No inputs. Nothing around it. Hooked up power to the amp, and the hum is even between the speakers and low in db! It measured 44 db (which is great and barely audible at my seat) on BOTH speakers, at 60 hz!


SO…. Something about the amp on the rack in the corner of my room. When restocking, I paid special attention to what I thought could cause any EMF interference. I moved my router to the opposite corner (as it was previously a foot away from the left channel on the amp), moving the router had no effect on the hum. I moved the LED lamp that is made of metal and also near the amp. No effect on the hum. Moving the WiFi router and moving the LED lamp had no effect on the hum when the amp was placed again on my stack in the corner of the room… !

SO… what is it about the amp in this location that causes a hum to be 6-10db more pronounced in my left channel only?


I had previously switched my speaker cables Left - Right, and the hum followed the left channel of the amp to my right speaker. So its something seemingly interfering with just my left channel on the amp when it is in the corner on my rack… Some thoughts:


-The rats nest of cables behind the stack? I rerouted the power cord for the amp only, as far away as possible from the rats nest of cables. No effect.

-The power strip that is behind the rack, that serves only to power my turntable motor and my iPad charger? I disconnect this power strip, no change.

-The electric Piano, which is 4’ away? It still present at that distance when I moved the amp to the center of the room and the hum reduced significantly.

-The coil of anticable that is behind my right speaker? Both speakers have 12’ of anticable, so the right one is coiled up a little near the left speaker input on the amp. I rerout the cable far away, no change.

-The Palm Plant??!! I move the plant…! It laughs at me! No change in hum….

-Could it be something about the physical stack?
-Could it be something about the proximity to the dedicated outlets I installed? They are right behind the amp, but nearer the right channel  and not the left….
-Could it be the composition of the walls themselves? The house is 100 years old, and I believe there is wood slat with plaster… could there be a metal mesh in this old wall type?

Is there some way I can insulate the amp from any of this interference?

What else could it be????

THANK YOU ALL FOR YOUR ADVICE!
The mysticism of this alchemy….


R,

They are now uncoiled! Forgive me!!!! I repent!