Transformers

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Lurcher300b
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Re: Transformers

Unread post by Lurcher300b » Mon Jan 16, 2017 2:53 pm

The only real issue with toroidal transformers comes when the case shorts on the central mounting bolt! Acrylic cases obviously prevent any such problems.
Only a problem if both ends of the bolt shorts to the case and creates a shorted turn.

Geoff.R.G
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Re: Transformers

Unread post by Geoff.R.G » Mon Jan 16, 2017 4:06 pm

Lurcher300b wrote:
The only real issue with toroidal transformers comes when the case shorts on the central mounting bolt! Acrylic cases obviously prevent any such problems.
Only a problem if both ends of the bolt shorts to the case and creates a shorted turn.
Generally it won't stay shorted for long, usually long enough to melt the case and start a fire.

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karatestu
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Re: Transformers

Unread post by karatestu » Mon Jan 16, 2017 6:44 pm

I wouldn't put an EI on the output stage of a class AB power amp but preamps, phono stage, dac, clock, cdp anologue stage are all fair game for a bit of experimenting i feel. Hey even the regulated front end of my power amps can benefit from an EI transformer i am lead to believe.

Stu
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BilliumB
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Re: Transformers

Unread post by BilliumB » Tue Jan 17, 2017 6:00 pm

I have read that a suitable EI transformer might be more effective than a toroidal in a Balanced Power Supply - possibly due to inherent filtering of noise on the 50Hz line. Anyone experimented with this?

Cheers. Bill

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Dr Bunsen Honeydew
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Re: Transformers

Unread post by Dr Bunsen Honeydew » Tue Jan 17, 2017 6:07 pm

Defeats a lot of the object as it increases source impedance.

Geoff.R.G
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Re: Transformers

Unread post by Geoff.R.G » Tue Jan 17, 2017 7:53 pm

These two articles may be of interest Sound Stage July 1998 and Audial 2013. Read these for some balance, [bryston.com/PDF/newsletters/Bryston_Newsletter_V8_4.pdf] [bryston.com/PDF/newsletters/Bryston_Newsletter_V8_5.pdf].
Now it is many years since I learned magnetic theory and mag amps so I can't vouch for the accuracy of the content of the above though magnetic saturation of the core rings bells, I'll remember why sooner or later. Google finds a huge number of entries, something like 24,000, so there is plenty to keep you awake on a cold night!

BilliumB
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Re: Transformers

Unread post by BilliumB » Wed Jan 18, 2017 12:47 am

Thanks Geoff - interesting papers well worth a read.

I certainly understand that Toroids offer lower impedance, and this must be good (and possibly paramount), whereas EI transformers offer better dc offset 'performance' and possibly a lower bandwidth (with potential noise blocking benefits). Interesting that the Audial people found that the EI transformers 'sounded' better than Toroids.

I remember discussing dc offset issues with Nick (Lurcher) a couple of years ago (I incorporated one of his dc blockers within a Ben Duncan isolation transformer, toroid based, that I use) - he suggested (I seem to remember) that an R Core transformer with a split bobbin might make a good basis for a Balanced Power Supply where high dc offset was present on the mains supply.

Any thoughts or experience anyone?

Cheers. Bill

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karatestu
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Re: Transformers

Unread post by karatestu » Fri May 12, 2017 8:14 pm

Has anybody any experience of the sonic benefits of using two identical single secondary transformers compared to one transformer with two identical secondaries ?

Is it worth doing ? Alot of space can be saved by having a transformer wound with two secondaries.
Naim, Linn & Harbeth fanboy

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Dr Bunsen Honeydew
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Re: Transformers

Unread post by Dr Bunsen Honeydew » Fri May 12, 2017 8:21 pm

Not a good idea, a transformer is not just the coils, the core is if anything more important than the windings, and should not be shared between windings.

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karatestu
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Re: Transformers

Unread post by karatestu » Sat May 13, 2017 7:26 am

Ok Doc.

It is a shame that most of my transformers have two windings. I will just have to make do with what i have :cry:

Coming from a mostly Naim background (sorry) i never thought it would do any harm - they seem to have a thing for using a large transformer with multiple windings.

I have done quite a bit of experimenting with transformer placement and found sonic benefits from moving things further apart even when there was no hum to begin with. I came to the conclusion that at least 20cm was needed between transformers and regulators, amplifiers, dacs, anologue stages and even between two transformers.

I was more or less laughed at or told i was hearing things by the objectivists at PFM, one of the reasons i found hfs and started posting here. The other time i got laughed at was when i removed the magnet which holds the cd draw in inside my naim cd player. I reported an improvement and was told it could not possibly make any difference.

Well, from that moment on i decided not to believe what any one said until i had tried it and heard with my own ears. I guess i was a subjectivist all along and just did not realise it.

Coming out feels so good. It is expensive though buying and tryingall these things.

All the best Doc.
Naim, Linn & Harbeth fanboy

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