audio output transformer design

RE: audio output transformer design, posted on June 20, 2012 at 09:59:12
drlowmu Manufacturer Posts: 7365 Location: East of Kansas City Joined: January 10, 2005	Why do you want to do that ?? Jeff Medwin

RE: audio output transformer design, posted on June 20, 2012 at 10:28:17

DanK tubes
Audiophile

Posts: 368
Location: California
Joined: November 9, 2004

There was an old reprinted article, published in Sound Practices magazine, that told you how to rewind a power transformer into a push-pull output transformer. It was a very rudimentry article. I know there are a lot of tricks for winding transformers, such as inerleaving, for optimum performance that are not covered in there.

I'm with Jeff on this one. Unless you just want to say you built the whole thing from scratch, you are probably better off just buying a nice set of iron from one of the established manufacturers.

Dan

RE: God is in the details!, posted on June 20, 2012 at 11:00:09

grhughes
Audiophile

Posts: 2476
Location: Central US
Joined: February 17, 2004

Firat of all you need to read many books on the subject and they are rare to find. Secondly you will need a layer winding machine that is carefully controlled, an up and a down turns counter and can handle wire from about 32 awg to about 10 awg. You will need a winding mandrel that is designed for the core size and paper NOT PLASTIC core forms. You will need multiple spools of Phelps Dodge wire of different awg and different laquer coatings as there will be many interleaved windings and they need to be color coded to keep track of them. Layer winding means that each turn is laid down right next to the last turn and not scrambled wound. There can not be any wire crossovers! Next will will need some good laminations of soft iron, grain oriented C cores like permendur that has been annealed. Next you will have to hand stack the laminations or C cores as they are fragile and dropping one from a table to the floor will ruin that lamination or core as it will completely alter the magnetic characteristics. If you're good at it you could probably wind and assemble two in a day. It is very time consuming and tedious. You have to make copious notes as the start and stop of a winding and which winding is what. They you will have to tie off and connect all these windings. Interleaving means that there will probably be 5 secondary windings and 4 primary windings step interleaved each with different size wire and no of turns. There are many tricks that have to be learned on the job. There are many ways to stack laminations and different ways of winding each with their own advantaes and disadvantages. I'm not trying to take the wind out of your sails, just you need to know what you're getting into. A good book to start with is the RCA Radiotron Designers Handbook by Langford Smith, 4th Edition. Good luck! Ray
"The gift of imagination is a gift of the Gods imparted to a few who receive innumerable kicks in the a$$ their entire life." Le Corbusier (Charles-Édouard Jeanneret)

RE: God is in the details!, posted on June 20, 2012 at 11:19:52

6bq5
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Posts: 592
Location: SF Bay
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Contributor
Since: September 14, 2012

Transformer winding is one of those Art/Science endeavors - You ought to know and understand the science, but that alone will not warrant a good outcome. You could be in for some trial and error also...
It can be figured out, there may be time to register for this show where I am sure you could get a good start

Happy Listening

Coil Winding in Berlin

I'm suprised to see that response from you, posted on June 20, 2012 at 15:27:58
bwb Audiophile Posts: 1303 Joined: July 25, 2011 Contributor Since: January 4, 2013	. Why? It is the DIY forum. He wants to do it for the same reasons we all want to do DIY stuff. You build your own amps and wind your own chokes if I'm not mistaken. Why not take a shot at transformers? I would try building DIY vacuum tubes if I thought I could pull it off. .

RE: audio output transformer design, posted on June 20, 2012 at 16:22:55
JerryG Audiophile Posts: 107 Joined: May 5, 2002	I saw it done and explained at youtube... check it out...

A very interesting NEW hobby to get into. Not for the faint of heart., posted on June 20, 2012 at 22:01:54

commentary

If you're a beginner, get as much knowledge and look up tools needed and check out minimum purchases for parts. Up front costs can be high.

Expect to make a few failures in winding cores. You're just a beginner. It would help enormously to have someone experienced train you. Good thing your minimum purchase wasn't too minimal. :-) Starting out with smallish 5 - 15 watt transformers helps you to learn with less material cost lost. And chances are they will sound better than big ones you try. And chances are they will be in the 350VDC area instead of 500VDC area which is more critical in winding lay and insulation.

Expect to learn for at least a year before you have a good transformer. Learn what it takes to separate HV windings from each other and the output as well. It needs to be able to insulate up to 1KV from primary to secondary.

Power output transformers have more constraints over small signal transformers. I have never tried anything but small signal. The winding doesn't have to be perfect lay, but it helps. You can fill up a section of winding by a semi-random back and forth laying of the winding and still sound good, but it isn't as well done as people with better winding technique. The thing is, the random winding cannot be so random as to cause overvoltage between windings. It is possible to avoid, which can be done by paying good attention to it. 1KV Hi-pot testing is very useful for final safety checks. But remember that arcing damage is always a risk for hand designed and built by beginner transformers.

I would not try gapping a SE transformer, but instead go for DC-prohibited designs: PP or parafeed style SE. Gapped transformers are for more advanced builds.

Finally, what's also discouraging is finding the right pieces that all fit together and buying from factory direct. You might need to start with a business name to be successful with getting small samples.

Or just buy it if it's available. I'll tell you it cost me more to build one by far than it was to buy an equivalent. Except I did get the ability to make more than just a pair and I did get to try out my own ideas (for fun). That's why this can be a somewhat expensive hobby. You're unlikely to make a profitable business out of it. Too much competition.

RE: A very interesting NEW hobby to get into. Not for the faint of heart., posted on June 20, 2012 at 22:09:53
drlowmu Manufacturer Posts: 7365 Location: East of Kansas City Joined: January 10, 2005	Or, you can buy a professionally designed and assembled EDCOR output for under $22 and be done with it. Jeff Medwin

Thank you! Very interesting! nt, posted on June 21, 2012 at 07:34:24
grhughes Audiophile Posts: 2476 Location: Central US Joined: February 17, 2004	nt "The gift of imagination is a gift of the Gods imparted to a few who receive innumerable kicks in the a$$ their entire life." Le Corbusier (Charles-Édouard Jeanneret)

RE: audio output transformer design, posted on June 22, 2012 at 00:00:45
airfield Audiophile Posts: 3 Joined: June 20, 2012	I want to learn how to design and wind output transformer.We have lots of tubes to build audio amps and I can't afford to buy commercially made output transformer.

one good reason, one not so much, posted on June 22, 2012 at 09:06:57

bwb
Audiophile

Posts: 1303
Joined: July 25, 2011
Contributor
Since: January 4, 2013

.

I want to learn how to design and wind output transformer.

good reason

I can't afford to buy commercially made output transformer.

not a good reason. You can't buy the parts and wind one as cheaply as you can buy one. It won't be the best but it will be as good or better than you can do until you've done a bunch of them.

.

http://www.edcorusa.com/

RE: one good reason, one not so much, posted on June 23, 2012 at 05:49:57
ray_babasa@yahoo.com	My father used to worked as a radio technician.He himself construct and winds output transformers but don't know how to design one.We have lots of EI cores from junked tube-type radio transmitters and receivers.And I am challenged because designing audio output transformers seems to be an arcane knowledge and skill.So I'm hopeful anyone out there DIY's can share and help me in my quest.

RE: Huge Task, posted on June 23, 2012 at 08:01:36
Neff	Study interleaving windings. I recommend fish paper vs plastic bobbin. Calculate winding fill. Tight fill is best. This is a real art & a little 'black magic'. Myself? I just pay someone & focus on other critera I am good (with some help).

RE: more info, posted on June 25, 2012 at 17:11:29

TubeBuilder

I wish I had seen this thread before I asked the question below. In my thread there is a winding machine for $400 there is also this link for amorphous c cores. I thought that I could start by buying some cores and make some bobbins and just fill it up and measure the inductance when I was done. There is lots of utube videos of some very good winders showing how to wind. I am curious what the smallest order number and cost of the cores are.

The winder can have a motor added which I would like. Even just winding good big low dcr speaker chokes would pay for the winder.Not sure if amorphous core can be used but I am guessing they would be good sounding. perhaps we could do a group buy on the cores.

http://www.alphacoredirect.com/contents/en-us/d185_amorphous

RE: audio output transformer design, posted on June 25, 2012 at 18:05:34
pictureguy Audiophile Posts: 2709 Location: SoCal Joined: October 19, 2008	You could always practice by winding me a couple inductors....aircore..... i have the design and requirements but suffer from lack of motivation. I'd also recommend buying larger spools of wire. The smaller spools are all 'respools' and can, not WILL, have either mistreated insulation or perhaps stretching...... These spools will go around 12lb each. Too much is never enough

RE: one good reason, one not so much, posted on June 25, 2012 at 21:14:38
drlowmu Manufacturer Posts: 7365 Location: East of Kansas City Joined: January 10, 2005	I could build a perfectly good SE 2A3 amp and use a $21 Edcor 2.5K to 8 Ohms output, and it would be FINE to hear !! For $21, why mess around winding? Also, I have custom wound, whatever magnetics I want to have, jeff Medwin

No wonder for you the power supply means everything., posted on June 25, 2012 at 22:07:53
commentary	You use $22 output transformers, so something else really needs to help it. :-)

RE: audio output transformer design, posted on June 26, 2012 at 09:19:51
airfield Audiophile Posts: 3 Joined: June 20, 2012	Aircores are for radio frequency not audio.Why not consulting any RF DIY for amateur.My concerns pertains to "AUDIO" not RF.

RE: audio output transformer design, posted on June 26, 2012 at 10:05:15
pictureguy Audiophile Posts: 2709 Location: SoCal Joined: October 19, 2008	Many vendors of aircore INDUCTORS for crossovers. Magnepan listeners use aircore inductors when upgrading and rebuilding the crossovers. power handling and saturation issues seem to be part of the equation. And yes, indeed, several online calculators are out there for the DIY inductor guy. I stayed away from the RF stuff. Too much is never enough

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audio output transformer design

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