Alch3my,
I would prefer it if people posted their applications questions here as it forms a reference for others so this is fine with me. Just bare in mind that you may have to wait a little for a reply as I am very busy nowadays.
There are pros and cons for each of the transformer construction methods and the results will also depend on the quality of construction materials and the attention to detail during construction.
Split bobbin transformers have poorer flux linkage than toroidal transformers, which generates larger stray magnetic fields around the transformers. They also have larger iron losses, which generates more heat for a given VA rating. They do show better isolation from the mains than standard toroidals, however an inter-winding screen can be fitted to a toroidal transformer that will give good isolation from mains noise.
I have tried many transformers over the years and I prefer the toroidal type, but not the off the shelf types from the main electronics distributors. These are built to a very low price to remain competitive in a general electronics market and are often noisy mechanically, especially in the larger sizes. They are usually built with high flux density to allow the use of a smaller core size for a given VA rating and they suffer core saturation problems, particularly at switch-on, because of their high flux density construction. This reduces the transient headroom dramatically. Core saturation effects can be quite severe with these high flux density transformers and this can strangle the dynamic presentation of the sound system and collapse the sound stage, not to mention causing large amounts if inter-modulation on the mains supply. This is likely to be the main reason people reject toroidal transformers for audio. It’s a shame really because when they are designed properly they do give very fine performance.
Price plays a big part in performance and you will not get high-end performance from a beer budget transformer. For my higher performance audio grade power supplies I have low flux density transformers, wound on oversize cores, to my specification by Canterbury Windings in the UK. This is not the whole story of the specification as non-disclosure agreements are in place regarding some of the parameters, preventing me from public discussion. However I can say that the resulting transformer is quiet, both mechanically and electrically, and it does not suffer from the core saturation problems that typical “off the shelf” low cost transformers do. These transformers give much better sound quality than any of the “off the shelf” transformers I have tried.
I hope this helps.
Regards
Paul
