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Old 28th April 2013, 11:59 AM   #11
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Nomex(410) is excellent but much much more expensive then paper or mylar(=polyester). Teflon has the same dielectric constant as paper but is also very expensive. Mylar is just cost efficient but not the right choice for audio transformers. Tribute for instance uses "paper" but that is pressed paper, very useable for audio transformers but normal paper is better because dielectric is lower. Nomex is also in many varieties so you have use a less pressed verion (410 or 411, other nomex types are less good then paper)


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Yes, Nomex is 4x more expensive compared to mylar or polyester.
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Old 28th April 2013, 06:44 PM   #12
DF96 is offline DF96  England
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Papaer is a traditional transformer insulation. It is supposed to be a fairly high quality paper - high clay content perhaps? I have heard that some Chinese transformers use recycled newspaper - about the lowest quality paper made, very hygroscopic.
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Old 28th April 2013, 07:12 PM   #13
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Traditional paper for transformers is called kraft paper which means brand new paper with no recycled paper.
I dont think recycled paper is really bad, just less strong

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Papaer is a traditional transformer insulation. It is supposed to be a fairly high quality paper - high clay content perhaps? I have heard that some Chinese transformers use recycled newspaper - about the lowest quality paper made, very hygroscopic.
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Old 28th April 2013, 07:20 PM   #14
M Gregg is offline M Gregg  United Kingdom
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Any thoughts,

On the sound quality compared to other insulation materials?
Does it have an impact or can it be overcome with winding topology..

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M. Gregg
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Old 28th April 2013, 07:29 PM   #15
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I guess not.

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Any thoughts,

On the sound quality compared to other insulation materials?
Does it have an impact or can it be overcome with winding topology..

Regards
M. Gregg
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Old 28th April 2013, 08:00 PM   #16
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Quote:
Originally Posted by M Gregg View Post
Any thoughts,
On the sound quality compared to other insulation materials?
Does it have an impact or can it be overcome with winding topology..
There is no direct impact on sound quality, but there is significant impact on other parameters of the transformer, which, in turn, may have considerable effect on sound quality and amplifier stability.

As I said before, organic paper and Nomex have lower dielectric constant compared to mylar, polyester, kapton or woven fiberglass used for interlayer transformer insulation. Thus, you can achieve lower stray capacitance and higher resonant frequency.

You can use fewer sections to reduce stray capacitance, but this will increase leakage inductance. You need to define your target parameters and constructional details of the transformer, and then decide if there is a need for more expensive insulation material.
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Old 28th April 2013, 08:38 PM   #17
DF96 is offline DF96  England
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Soft paper may allow windings to move slightly so allowing some transformer noise and possibly distortion. Hygroscopic paper will attract and retain moisture which could allow electrolysis to occur wherever the windings have a crack in the wire insulation - the result will be shorter lifetime before the transformer develops a shorted turn.

The right sort of paper will work just as well as any other insulator.
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Old 28th April 2013, 08:54 PM   #18
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Paper will be always a little hygroscopic, the same is for nomex.
Both have been profed to be excellent over a long period of time without problems.
Maybe in a tropical climate there must be some precautions.
You can use wax to impregnate it.

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Originally Posted by DF96 View Post
Soft paper may allow windings to move slightly so allowing some transformer noise and possibly distortion. Hygroscopic paper will attract and retain moisture which could allow electrolysis to occur wherever the windings have a crack in the wire insulation - the result will be shorter lifetime before the transformer develops a shorted turn.

The right sort of paper will work just as well as any other insulator.
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Old 21st July 2014, 06:27 AM   #19
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Smile Nomex and polyester

I used Nomex 410 between primary and secondary layers, polyester between primary layers, the resonant is above 100k (very happy the result)
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Old 21st July 2014, 12:25 PM   #20
M Gregg is offline M Gregg  United Kingdom
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Just for interest,

40-18080

I have no connection and I haven't got a clue what they sound like..

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M. Gregg
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