diytube.com

Using the Edcor GXSE-10 and the Edcor XPWR transformers... which arrangement would you choose?

Shannon built his this way... we'll call this option A.


Dynaco arranged the ST35 this way, sort of. The GXSE are a little different in that they lay down on their long side, rather than stand upright. You can call this one option B.

Morgan Jones in "Building Valve Amplifiers" (pages 10-11) votes for #1, saying that 'transformers leak most flux along the axis of their coils and where the edges of their coils are furthest from the core.' Meaning aim the PT's laminations at the tubes. I think....

George

I use the "A" configuration almost all of the time. The only exceptions seem
to be when "B" is physically a better fit on a small chassis, like a diytube
ST-35 in a 12x8 chassis.

I use "A" because the EMF off the power tranny is the least off the corners (45 degrees) and induces the least hum in the tubes in the position in front of the OPT's.

I put the rectifier right in the middle, where there's no worries about hum.

Now if you have a Z-mount (like a PA-060), make sure the centre leg is aimed at the output trannies.

Cheers!

My methodology was merely to keep the Edcor labels facing forward.

Shannon

separks wrote:My methodology was merely to keep the Edcor labels facing forward.

Shannon

Brian & Phyllis should give you a deal for that

Cheers!

I have not built as many amps as some people herhume, but I haven't noticed any induced hum from transformer leakage. Sure, physics says it's possible, but why would you hide those Edcor labels?

Pete Millett made his(and so did most of the builders) Jonokuchi spud amp in B configuration.

http://www.pmillett.com/Jonokuchi.htm

Well, I think I'm still every bit as uncertain as I was when I started.

I might just go with whatever seems to fit best...

I normally use the"A" orientation, but in most cases, it really doesn't make any difference, as long as the OPT cores are 90 degrees separated from the PT.

If you use a PSU choke like the C354, its core is oriented vertically, so it wil be oriented 90 degrees "orthagonally" (mutually exclusively) from both the OPTs and the PT cores.

Mostly, it's just a matter of personal aesthetics, whatever looks best is the way to go

/ed B

I wonder if you could get the GXSE-15xx transformers made with vertical end covers instead of horizontal? I'm planning on using a Hammond 10x6 box and that would free up some real estate!

Ty_Bower wrote:Well, I think I'm still every bit as uncertain as I was when I started.

The vote is 4:1 for "A".... how you confused, bro?

Cheers!

Geek wrote:The vote is 4:1 for "A".... how you confused, bro?

Fine, fine. The A's have it.



It'll look better after I prime and paint it.

Ty, if I can be nosy, what is the size of your chassis plate? I'm looking at 9x12 or so for mine, and yours looks like it might be about the same. Just wondering if I'm making it too big. Thanks.

George

It is 10 5/8" wide by 8 1/8" front to back. The transformers will be GXSE10, whenever they get here.

I've always made my chassis plates out of whatever scrap aluminum I could dig up, and this is what I found. If I moved the transformers a little closer to each other, it would fit on a 9" wide chassis without too much trouble. If I moved all the binding posts, input jacks, etc to a rear apron (like on a Hammond chassis), I might be able to squeeze everything onto a 6" chassis (front to back), but I don't think I would recommend it.

I typically use 1/8" thick aluminum plate, but this piece was about half that thickness. I'm pretty sure it's going to flex once the transformers are on, and I'm going to need to reinforce it from the bottom with a piece of angle.

You can never make a chassis too big. Just spread the transformers apart more.