What wire to wind toroidal core inductors? (41hz Amp4)

[Peteruk]

Hey all,

Further to my thread on what cores to use on the toroidal output inductors of my amp4 kit, I realised I now need to decide what wire to wind them with.

Now, I am using Metglas (Anamorphous) Cores, whom supplied them with the recommendation I needed 13 turns of 1.2mm wire on each to make them ideal for my requirements. I thought getting the wire would be quite straightforward- a simple piece of standard copper wire.

However, I didn’t realise how much division there was over which material is best, and hadn’t even begun to consider insulation.

While some successful amps have used copper (such as the Red Wine Audio Signature 30), some people have expressed the view that silver is a sonically favourable material. As one person put it:

“The difference between copper and silver wire is far greater the then numbers would suggest. In fact, I doubt that the difference would be very noticeable if it were only the conductivity. Silver has an entirely different sound that is particularly noticeable in the higher registers and in the overall detail and soundstaging. The use of silver is what Audionote Japan famous. Hand drawing silver takes things a step further because, unlike machine made silver wire and ribbon, The successive drawing of the material through progressively smaller dies creates a material the is essentially a monocrystal.”

On the other hand, some have pointed out that Silver is harder to handle, which as a result, means it is harder to wind both tightly, and evenly, around the core, factors which could have a greater impact on the result (apparently).

Additionally, silver costs significantly more, and some people have stated it could sound ‘brighter’, which might be an issue for me, considering Tripath amps are supposed to sound bright anyway, and my Monitor Audio BR2s are a tad on the bright side too.

As for insulation, whereas Teflon is common and cheap, natural materials are said to make a more natural sound. However I am undecided as to whether this is true.

Electrum Audio, who I go to to find many good audio bits cheap, have 1.2mm hand drawn .999% silver insulated with cotton that has been permeated with beeswax for $6.00 per foot with an additional $2.00 per foot cryogenic treatment option. However, unfortunately there is a 10 foot minimum order.

Any opinions on this would be greatly appreciated!

Thanks,
Peter

[Peteruk]

Anyone have any opinions?

I'd also like to expand the topic to hook-up wire, as I imagine I'll use similar for that too.

[BWRX]

Use copper wire. Save your money for something more worthwhile.

[Peteruk]

Originally posted by BWRX
Use copper wire. Save your money for something more worthwhile.

Fair enough. Any suggestions for sources?

Just to check - when winding the inductors, the wire used must have at least some kind of insulation, correct?

I.E. Bare wire cannot be used.

[BWRX]

Originally posted by Peteruk
Just to check - when winding the inductors, the wire used must have at least some kind of insulation, correct?

I.E. Bare wire cannot be used.

Absolutely correct. You do not want the windings to short out.

[bzdang]

Originally posted by Peteruk



Fair enough. Any suggestions for sources?

Just to check - when winding the inductors, the wire used must have at least some kind of insulation, correct?

I.E. Bare wire cannot be used.

Magnet wire is common and should be available from many suppliers of things electrical.

Insulation of magnet wire is often 'Polythermaleze' which can be stripped with heat, or polyurethane which must be scraped or sanded off before soldering.

Here is a useful table for comparing AWG and diameter in mm.
http://www.powerstream.com/Wire_Size.htm

[postalrat]

How about litz wire? Since I have to window another 16 inductors Im looking for an easier way out. Litz wire seems it should be a lot easier to wind.

Or does anyone know a good supplier of 10uh inductors?

[audiosteve]

Check out Jameco. They have some very inexpensive, high current, 10uH toroid inductors.

[lumanauw]

Is it possible to use litz or parrareled (smaller) magnet wire for classD output inductor?

I see examples of commercial classD product, they tend to use only 1 wire (with big diameter) for output inductor. The switching frequency can be 300-500khz, the skin effect will be dominant.

But why those products only uses 1 big wire instead of some smaller parrareled wires?

[BWRX]

Originally posted by lumanauw
Is it possible to use litz or parrareled (smaller) magnet wire for classD output inductor?

Of course.

Originally posted by lumanauw
But why those products only uses 1 big wire instead of some smaller parrareled wires?

It's due to manufacturing and cost. I don't know if there are machines capable of winding litz wire.