• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Orientation of E-I core OPT and toroidal power transformer

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Member
Joined 2009
Paid Member
Folks,

Eventually, I will get to try this in the lab, but I figured I could give myself a head start by asking out loud:

With a toroidal power transformer and regular E-I core OPT's, what is the preferred orientation of the OPT's with respect to the toroid?

My current thinking is to have the toroid 'above deck' and the OPT's 'below deck' to save space. The 'deck' is 1/16" (1.6 mm) aluminum. While the leakage fields from a toroid typically are pretty low, they're not zero. I'd still think I should be able to achieve some form of optimal placement that would eliminate any hum. But where to start...

Any input?

And happy Festivus everybody.

~Tom
 
No serious experiment, but I have built an amp that is "backwards" from your proposed design. The toroidal power transformer is below the deck, nearly under the OPT's which are on the top of the deck. I used this layout because I painted the OPT's gloss black, but the Antek toroid is ugly unless I found a pretty box or can to put it in. This was a "zero budget" amp, built with parts that I already had.

Pictures are in post #189 in this thread. The amp had been tested, then disassembled, then all of the finishing and painting was done, then partially reassembled when the pictures were taken. The deck is 1/16 inch aluminum.


http://www.diyaudio.com/forums/tubes-valves/148694-tubelab-simple-p-p.html?highlight=Simple
 
Member
Joined 2009
Paid Member
George,

Nice woodwork on the Simple P-P! I'm trying to do something similar for the chassis for my Spud, though, I'm using walnut wood. Nice stuff. But my woodworking skills are nowhere near yours. It'll be decent, but I expect the mitered corners to have a couple of gaps as my miter saw apparently was set up for 45.5 degrees and not 45 degrees. Oh, well. Live and learn.

I'm curious to hear what your conclusions are for the Simple P-P as far as noise/hum goes.

I'm using an Antek 1T250 for power transformer and the matching CA-100 steel pot for it. Those pots are quite stout - it probably weighs as much as the transformer. Unfortunately, there'll be a 1 mm gap between the deck and the pot so the pot doesn't form a shorted turn on the transformer. And the pot has a couple of notches (about 1/8" deep) to allow the wires to come out. I'm hoping I can fill the gap and cover those notches with a gasket of some sort. I'll be running the wires through the deck (1/16" aluminum) and cover everything with the pot. It should be pretty decent...

~Tom
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.