Transformer Noise: What is Normal?

[rsmiii]

Recently completed my Kaiju 300B with the DC Filament Supply Upgrade.
Tested over several days through my 1959 Motorola Console speakers – picture attached.
It's superb, absolutely superb! Fun and delightful!
Speakers are dead quiet except for the music itself – no detectable speaker hum, buzz, whatever.
Again, I am so happy and faintly astonished I was able to build this product successfully.

I have one question: the PT-9 transformer (I think?) does make some noise.
It's not really bothersome; it's pretty quiet.

Is some level of transformer noise usual?
Bottlehead products is pretty much all I know about tube amplifiers so I have nothing to compare it to.
Again – absolutely none of the "transformer noise" comes out the speakers.
Advice appreciated.

[Paul Birkeland]

A little bit of transformer noise from the PT-9 isn't unusual, but you'd want to be sure that the transformer screws are nice and tight.

[johnsonad]

My Kaiju does the same. I’m going to tighten it down as PB suggests.

[Lowercase]

I know this is an older post, but thought it would be better than creating a new thread.

Is there a distance for hearing the hum that is considered normal? Some say they only hear it with their ear right up to the transformer, others from a bit of a distance. I can easily pick it out when no music is playing from about 6 feet away, my listening distance. Within arms reach the noise is audible with music playing at a relaxed listening level. I feel like I’ve tightened mine down as far as I can/should take it, but do I need to break out my torque wrench to get to a certain point?

[newfangled]

I would also like to know what's considered normal for hum from the transformer. I have the DC filament upgrade and don't hear any hum from the speakers. When music is paused or even quiet passages I can easily hear hum directly from the PT9 power transformer. The hum is easily audible when standing at the back of my acoustically treated room 20 feet away.

I tightened the 4 screws securing the transformer as much as I feel comfortable taking them and there was no difference. I don’t see any solder issues. Wondering if the hum is normal or if there’s something I can do to reduce the hum.