London Power ad

Search the Forum

(Advanced Search)

Wire Size For Power & Output Transformers
What size or sizes of wire would be used in making power and output transformers?

I believe the question is a bit broad, so the answer is necessarily going to be broad or, dare I say, vague.

Just as with wiring the rest of the amplifier, the wire size needed in a power or output transformer depends on the current involved, in this case, for each winding. A power transformer is relatively simple since there is only one physical winding per secondary. Obviously a 5A heater winding needs a thicker wire than a 100mA plate winding. The guauges here will follow the listings for regular hookup wire for external wiring, or close to it. The insulation is thinner because the adjacent loops of the coil are a very low voltage apart.

Output transformers are more difficult to wind as each winding must be split into sections and interleaved with the sections of the other windings. Otherwise, the frequency response will be no better than that of a power transformer. This gets to be more tricky and you have to meticulously mark all the sect ends and keep track of what ultimately connects to what. The sectioning of the output transformer likely leads to the use of thinner wire than the net winding might require as some sections may be wired in parallel in the end.

For an OT you may end up with an overall section that spans the half-winding length (centre-tap to one end) to assist in reducing parasitics.

A problem Mr. O'Connor reported is with regards to "skaning", which relates to the tension on the wire while winding. Too high a tension can stress the wire and when the entire assembly is dipped and/or fully taped completed, there may be a broken winding or section.

If you are truly interested in winding transformers, you have to invest in books dedicated to that subject. I have heard from others that the problems acquiring core sections and end bells and such like outweigh the benefit of winding it yourself, but that is probably an individual decision regarding "worth".

I believe the best advice is to try as much as possible to base your build upon available parts. If those won't meet your requirements, submit a request-for-quote to a few transformer manufacturers and maybe talk to their design consultants.

Thank you for your reply, appreciated, can you refer me to any suitable books that deal with winding transformers?

Forum Jump:

Come in where it's warm!
A warm welcome to tube amp modding fans and those interested in hi-fi audio! Readers of Kevin O'Connor's The Ultimate Tone (TUT) book series form a part of our population. Kevin O'Connor is the creator of the popular Power Scaling methodology for amplifiers.
Please remember these three principles: respect, sharing, community.
Not familiar with The Ultimate Tone book series? See discussion topics, or click here to visit London Power/Power Press Publishing.

Tube Amp Forum Hosted by London Power
London Power logo