Transformer orientation/location considerations

[fdesalvo]

Ello, ello!  

I'm planning my layout on a tight chassis 12.5" x 6.5" x 2.5" and I'm going to be forced to place either the OT or choke beneath the preamp side of the circuit board.   What do I need to know at this point?  

So far, I've made templates of the circuit board and all trannies, so I can move them about within a 1:1 scale drawing of the chassis and am finding that there will be some sort of compromise.  I've seen some really tight spacing in others' builds, but I'm not sure how others have managed to successfully mitigate noise issues.  How should I proceed?  

Thanks,

~F

[HotBluePlates]

What kind of circuit? Is this a tweed build (the dimensions sound roughly tweed-like)?

Are you tied to this chassis? Is it aluminum or steel?

[fdesalvo]

Hey, brotha - was hoping you saw this.

Pretty tied to it - it's a single channel/40w AB763.  Chassis is aluminum.

What kind of circuit? Is this a tweed build (the dimensions sound roughly tweed-like)?

Are you tied to this chassis? Is it aluminum or steel?

[fdesalvo]

Anyone with any insight - short of, "buy a longer chassis"?  I've seen this sugsted on a few forums:

"....it's also true that it's best to have the cores of each trannie at 90 degrees to one another. This minimizes any hum coupling between them. On some hifi amps the designer would actually drill only one mounting hole on the output transformer so he could rotate it a bit from exactly 90 degrees. If you put voltage into the power transformer and a pair of headphones on the output transformer you can actually hear any induced hum. The nature of making transformers means that things rarely are exactly symmetrical. Often he'd find that a few degrees either way hit the "sweet spot" or the absolutely least amount of hum pickup."

Edit - nm, Soldano/Orange manage to place their OT's on the opposite side of the chassis (some with the chocke on the inside!) with zero issues.  I'll study up.

[firemedic]

You can put the choke anywhere you want. Even inside the chassis.

OT placement may be more critical but it depends a lot on who you ask about it. You see them in many locations on different amps & that seems to be fine.
 
The noise-inducing transformer is the PT. Just mind the orientation of the other transformers & you should be good to go.

[fdesalvo]

^your opinion seems to mirror much of what I've been reading.  Much thanks.

I'm converting the PT to a standup using some endbell adaptors and am wondering how this effect orientation.