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?

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?


--
Wally
www.artbywally.com
www.wally.myby.co.uk

"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.


--
Trevor Wilson
www.rageaudio.com.au

In article , Trevor Wilson trevor@SPAMB
LOCKrageaudio.com.au writes

"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.



Two websites of trannie manufacturers that some may find of interest. I
bet there isn't some audio in the world that hasn't been through one of
these companies metal at some time or another!....

Http://www.lundahl.se/


Http://www.sowter.co.uk
--
Tony Sayer

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.

--
Nick

"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

Trevor Wilson wrote:

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.

Does that mean that the specifics of the lay-up aren't too critical?


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.

Are there substantial savings to be made by winding them oneself? Any major
pitfalls?


**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.

Righto.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

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

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.

Does that mean that the specifics of the lay-up aren't too critical?

**Nope. Any good transformer (and output transformers are more critical than
power) requires a nice lay of the windings. A messy lay will ensure that the
transformer may not demonstrate predicted performance. It will also reduce
efficiency and proper coupling. This will affect the frequency extremes.



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.

Are there substantial savings to be made by winding them oneself? Any
major
pitfalls?

**I've never wound one, but, it ain't rocket science. It is more of a 'black
art'. Experienced winders are sought after for their talents. So, I say: Go
for it. If you have the time, patience and inclination, then it could be a
rewarding hobby. I have wound a few power transformers, with a speed
controlled electric drill, and normal workshop equipment. It was not much
fun, but satisfying, since I needed a low profile transformer, which was not
available at the time (early 1970s). Now, they're easy and cheap to obtain.
(GRRR)



**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.

Righto.

**Just a guess, mind you. You could ask a transformer winder. He/she might
tell you. Look in the Yellow pages (or whatever your Pommy equivalent is)
and choose a smaller manufacturer and call them up. You may be surprised to
learn that they may even supply all the materials you need. Or not.


--
Trevor Wilson
www.rageaudio.com.au

Trevor Wilson wrote:

Does that mean that the specifics of the lay-up aren't too critical?

**Nope. Any good transformer (and output transformers are more
critical than power) requires a nice lay of the windings. A messy lay
will ensure that the transformer may not demonstrate predicted
performance. It will also reduce efficiency and proper coupling. This
will affect the frequency extremes.

Duly noted. Are there any particular patterns that are preferable, or is a
neat side-by-side lay-up okay?


Are there substantial savings to be made by winding them oneself?
Any major pitfalls?

**I've never wound one, but, it ain't rocket science. It is more of a
'black art'. Experienced winders are sought after for their talents.
So, I say: Go for it. If you have the time, patience and inclination,
then it could be a rewarding hobby. I have wound a few power
transformers, with a speed controlled electric drill, and normal
workshop equipment. It was not much fun, but satisfying, since I
needed a low profile transformer, which was not available at the time
(early 1970s). Now, they're easy and cheap to obtain. (GRRR)

I've got a little lathe with electronic speed control (and a back-geared
reversible leadscrew) and I've been interested in trying some coil winding
for a while. While I can appreciate the black art aspect, it strikes me that
working to an established spec should produce a reasonable result. IOW, a
careful build using the right gauge of wire and the right number of turns
should get a decent result that's nearer to the high end kit than the
'cooking' transformers.


**Just a guess, mind you. You could ask a transformer winder. He/she
might tell you. Look in the Yellow pages (or whatever your Pommy
equivalent is) ...

I believe it's called 'the internet'. :-)

... and choose a smaller manufacturer and call them up.
You may be surprised to learn that they may even supply all the
materials you need. Or not.

I'll see what I can come up with.


--
Wally
www.artbywally.com
www.wally.myby.co.uk

In a world of inflated prices, just a reminder that Maplins 6.6K OPT is
actually rather a nice performer (Thorsten Loesch thinks so too). Around £30
and that's not bad. Next cheapest is http://www.vvttransformers.co.uk/

If you want a few, check the very nice toroidal OPTs from Antrim - they need to
wind 10 for an order, but very good prices and nice people.
http://www.antrimtransformers.com/Valve_psu.htm

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

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

Does that mean that the specifics of the lay-up aren't too critical?

**Nope. Any good transformer (and output transformers are more
critical than power) requires a nice lay of the windings. A messy lay
will ensure that the transformer may not demonstrate predicted
performance. It will also reduce efficiency and proper coupling. This
will affect the frequency extremes.

Duly noted. Are there any particular patterns that are preferable, or is a
neat side-by-side lay-up okay?

**Here's where you really should talk to someone who REALLY knows what
they're talking about. Side by side is fine, AFAIK. Then lay the next
winding on top.



Are there substantial savings to be made by winding them oneself?
Any major pitfalls?

**I've never wound one, but, it ain't rocket science. It is more of a
'black art'. Experienced winders are sought after for their talents.
So, I say: Go for it. If you have the time, patience and inclination,
then it could be a rewarding hobby. I have wound a few power
transformers, with a speed controlled electric drill, and normal
workshop equipment. It was not much fun, but satisfying, since I
needed a low profile transformer, which was not available at the time
(early 1970s). Now, they're easy and cheap to obtain. (GRRR)

I've got a little lathe with electronic speed control (and a back-geared
reversible leadscrew) and I've been interested in trying some coil winding
for a while. While I can appreciate the black art aspect, it strikes me
that
working to an established spec should produce a reasonable result. IOW, a
careful build using the right gauge of wire and the right number of turns
should get a decent result that's nearer to the high end kit than the
'cooking' transformers.

**Sure. As long as you can drop your lathe down low enough in speed, I don't
see a major difficulty. Big wire demands very low winding speeds. Thin wire
requires enormous care.



**Just a guess, mind you. You could ask a transformer winder. He/she
might tell you. Look in the Yellow pages (or whatever your Pommy
equivalent is) ...

I believe it's called 'the internet'. :-)

**We're gonna get that internet thingy down here, real soon now.


... and choose a smaller manufacturer and call them up.
You may be surprised to learn that they may even supply all the
materials you need. Or not.

I'll see what I can come up with.

**Good luck. At worst, it will be entertaining. Whilst there are probably
lots of books around, you might try to secure a copy of the Radiotron
Designer's Handbook. I don't have one, but I'll betcha transformer winding
is covered therein.


--
Trevor Wilson
www.rageaudio.com.au