[333jeffery]

What is an r-core transformer, and why would you want one in an audio amplifier? Is it better than, say, an toroidal transformer? Thanks for any info.

 

[Chris J]

 
Have you tried googling this? Questions and answers like this usually depend on application, cost, etc.
 
They seem to be more compact than "standard" EI core transformers.
They also leak less magnetic flux than EI transformers, which works out to less magnettically induced noise from the transformer into the rest of the audio curcuitry.