HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

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.

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.

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

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

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

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!

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

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.

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.

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

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.