Output transformer & choke location

[MrBreeze]

Ive got my 5F2 chassis and trying to detemine where the output transformer and choke should go.  Two choices appear reasonable.  One has power, then output then choke and no new holes to drill (1st photo).  The other is power, choke and then output w/ 1 new drilled hole (2nd photo).  Seems like no magnetic field issues with either but one may be better for hookups to the board.  Any opinions on which layout is better overall?

[HotBluePlates]

I would prefer the output transformer further from the power transformer.  Keeps the hum out.

You can put the transformer anywhere on the chassis (that speaker-fit allows).  Simply allow a longer wire-run outside of the chassis before the wire duck in through the grommeted hole.

[chaswahl]

Here's a theoretical diagram (attached below):
from "Designing Vacuum Tube Amplifiers and Related Topics" by Charles R. Crouch
https://www.guitarstudio.tv/documents/Designing-V-T-Amplifiers.pdf page 155 or thereabouts.

The best empirical method I know of is the "headphones" test, with PT powered and headphones connected to the secondary of the (disconnected!) OT; move around to find the least noise. I don't know whether it makes much difference to the choke. Described herein:
https://www.tdpri.com/threads/transformers-minimizing-coupling.549494/

Note that for a laydown PT, there's a (marginal?) difference between having the long side of the EI laminations facing the OT (probably most common, due to physical space considerations prevailing), and the (presumably better) short side facing OT. Also discussed in the thread linked-to above.

[pdf64]

It’s worth noting that 45 & 50W type Marshall chassis put their PT and OT really close together, maybe 1/4” separation.
And are typically used with closed back, sealed cabs.
Yet their mains frequency hum can be pretty much undetectable.

[dude]

As HBP mentions put OT where best fit but run secondary's through a grommet on the under "outside of chassis" then back to speaker jack. I has a build that I was forced due to space to have the OT too close to the PT, I had unwanted hum, noise, etc. I ran the speaker wires under the chassis, and noise vanished.