"Nick Gorham" wrote in message
...
Trevor Wilson wrote:
"Wally" wrote in message
...

Trevor Wilson wrote:


**To be honest, I haven't watched a rewinder ply his craft. However,
the usual method is to rotate the former. With a power transformer
(and cheap, crappy valve amp output transformers), it is a two step
operation. 1) Wind primary.
2) Wind secondary.

With a quality, interleaved output transformer, it goes kinda like
this: 1) Wind some primary.
2) Terminate.
3) Wind some secondary.
4) Terminate.
5) - N) Repeat for the required number of interleaves.

So, it's basically the same method as the two-layer version, repeated.

Does

the lay-up of the winding have to be done in some kind of even pattern,
or
can it just be wound on to produce layers of even thickness? You said
that
the process is difficult to get right - what bits would be difficult to

get

right?


**The process is not so much difficult, as time consuming and hence,
expensive. With valve amplifier output transformers, there is no such
thing
as a 'free lunch'. You want a quality amp, you MUST spend the Quid on
decent
output transformers.


What's the deal with the grain-oriented plates? What advantage(s) do
they
have, and how pricey are they compared to the non-oriented variety?


**Low losses, high permeability, which provide better performance than
regular steel. I don't know about the cost. I would speculate that
around
300% higher than the regular stuff.



I don't know about the cost, the person I know who winds his own TX's
only uses M6 anyway. I agree entirly with Trevor on every point other
than the prices he quoted earlier. For example Sowter which I would
suggest is a good example of a quality UK winder, uses M6, and their
audio power transformers are interleaved. A SE TX for a GM70 (for
example) would cost about £300. A similar C-Core from Lundahl is £400,
and I was quoted about £500 for a Amorphous cored transformer from
Tribute. All for pairs

http://www.republika.pl/diytriode/dr...s/image002.jpg

I just wanted to point out that while you can pay the price Trevor
quoted, I wouldn't look down the nose at a TX at half the prices given.

**I am not intimately acquainted with the UK market. As such, my approximate
prices were exactly that. Having said that, I'll go out on a limb and assume
that those trannies were 200 Watts or less. Taking the low end of your
pricing, that is 150 Squid each. As an example of the type of transformer
which _could_ be found in a budget valve amp, I would direct the reader to
www.farnell.co.uk and part # 4337426. This item is a 500VA power
transformer, which Farnell sells for 25 Squid.

That should put into perspective the price differences between power
transformers (which are often used in cheap, crappy, but nice looking,
contemporary valve amplifiers) and proper output transformers.

And just to remind our rude friend, Fleetie, that output transformers,
although the most expensive single part of any decent valve amp, are just
part of the story.

--
Trevor Wilson
www.rageaudio.com.au