Layout in amplifiers with transformator one in each end.

[überfuzz]

I'm about the fix a chassis to an amplifier and I haven't decided where to place the 'trafos'.

Up to now I've gone with the Fender style and placed them both in one end. Now I like to try and put them one in each end of the chassis, but I don't know how to wire or set up the layout to get it stable with this kind of set up.

Any links or wise words to share..?

[loudthud]

Sunn amps used this type layout on many of their tube amps. They usually did not use an eyelet board but connected components between terminal strips and the tube sockets. A wiring harness connected everything together. The preamp tube sockets were located right behind the front panel with the transformers towards the back. Power tubes were between the transformers towards the back. Early amps were fairly low gain. The Model T was like the 5F6A (moderate gain). There was a higher gain amp, The Enforcer, but I've never seen the insides of one of those.

[Steve Conner]

With this layout style, you have two options. Either the PT will end up next to the input jack end of the preamp, or the OT will.

I always lay it out so it is the OT. My reasoning is that a tiny bit of hum induction will be more noticeable than the same amount of induction of the signal itself, because the hum is there all the time, but the signal is masked by itself. So, induction from the OT back into the preamp just needs to be kept low enough to avoid instability when everything is turned up full.

Tube circuitry is high impedance, which makes it much more sensitive to electric fields than magnetic ones. Therefore the critical part in this layout is not the OT itself, but the wires from the power tube anodes to the OT primary, which have to come all the way back along the chassis. They run the gauntlet of the entire preamp, and have to be Faraday-shielded from it or the amp will oscillate horribly. The easiest way is simply to run them outside the chassis from the OT end to the power tube end.

The wires from the OT secondary to the speaker jacks should get similar treatment, but it's not as important because the voltage on them is lower.

[Diablo]

Here's the layout on a Ceriatone Dizzy 30. I built one and followed the design and it's very quiet and well behaved.
http://www.ceriatone.com/images/layo...0Ceriatone.jpg