"Ian Iveson" wrote in message
...

Phil Allison"

** Better leave this para in since this is the one I referred to.

In addition to sensible advice so far, and linked to the turns ratio
thing...a transformer allows for thick, high-current output winding,
and thin (therefore compact, low-leakage etc.) primary. An
autotransformer could do the same but only by compromising the
advantages you state.

** Autos have less copper losses and much better bandwidth than
an isolation type.

Sometimes. Is that what ** means?

** Nope.


** Wanna compare figures on a 4:1 impedance step down toroidal with a 160
VA size core ?


Read the other posts that I agreed with. 4:1 is easy. 400:1 is nearer
what most people would use here.


** Even then it would not need to be inferior to a isolation type.


Neither would 160VA be appropriate in most cases.


** The same comment applies to a wide range of VAs .


Care to cite a reasonable comparison?

** Your face and a monkey's behind ?



Care to back up your statement about "much" wider bandwidth, in the
context of an OPT for a domestic valve amp?

** My remark sits quite well in the original context.


Can you think of any other important parameters other than copper losses
and bandwidth?

** None that relate to my comment.


Ever wondered why no-one uses, or supplies, auto-transformers for valve
amp OPTs?

** Never wondered at all.

The reason is so bleeding obvious.





............. Phil