torodial transformers?

[pmkap]

pmkap:

I do not for one moment believe that an unshielded, inexpensive toroidal transformer is unsuitable for use in audio-equipment power supplies.

Wes

Of course you don't.... nor did I say they were not suitable. I'm simply saying there are better alternatives. My solid state poweramps use bog standard Avel toroids. I didn't wan't to muck other geometries with their external magnetic fields and its predeliction to cause hum, and at the time, I was unwilling to spend double the cost for interwinding shielded ones. We all make our decisions based upon both technical and economic constraints.

But when it comes to solid state source components or a popgun supply for a T-amp, and I see a toroid lacking an interwinding shield, I'm saddened. Saddened because, at least for a simple split or single rail ps, one could use a flat pack transformer which minimizes external magnetic fields, has far less capacitive coupling and bandwidth, and is roughly equivalent in cost. I don't care how good your regulators may be, these transformers will simply produce a better component.
http://www.mcitransformer.com/i_4-05_2.html

Then again, I live in NYC, and where you live your mains may well be perfect, noise free sine waves. I'm very happy for you.

Nor do I particularly care that you 'do not believe for one minute....', because if you'd actually tried, or evaluated alternatives, you would have said so. You simply stated your 'belief', not anything based upon empirical experience or technical knowledge. Faith based engineering..... thats a new one.

 

[planet10]

I was going to recommend checking out the fellow member from Turkey who is selling c-Core trafos made in his locale... but with someone in Telaviv making them, that might well be a better place to go (i'd take a c-core over a toroid -- all else equal)

dave

 

[AndrewT]

Hi wintermute,
I have not tried it but I read that removing the single core secondary output tails and replacing them with flexible cords allows you to move the transformers around without work hardening the copper tails (and risk breaking them).
Now you can rotate the toroid around its mounting bolt to minimise the hum field effect on the adjacent circuit.

 

[wintermute]

Thanks AndrewT,

I hadn't even thought about rotating the transformer, but given what magnetic fields look like (with poles) it makes sense!! When I next feel brave enough to open up the amp (when I put in a new rectifier/cap board) I'll have to give it a try.

Tony.