I have a line-level audio output stage with an output impedance between 100-600 Ohms and an input stage with an input impedance of 10-20kOhms. I am looking to use an isolation transformer to connect these stages, isolate them and eliminate common mode noise between them. I am looking at audio transformers, and I have the option between 600CT:600CT or 10,000CT:10,000CT impedances.
Maybe I'm misunderstanding this, but it has been mentioned in previous posts that these impedance ratings refer to the load impedance for which the transformer is designed, as it will have the flattest output response in the region in which it is designed to operate. So am I correct in assuming that I need a 10,000CT:10,000CT transformer?
I feel like this specification is confusing, as 1:1 signal isolation transformers are not designed to transfer power, and the specification suggests that both input and output stages should have the same impedance. It also could be easy to interpret it as meaning that 10,000 Ohms is the impedance of each coil itself. Can someone please clarify?
EDIT: For anyone else looking for similar information, check out this very informative article on designing circuits using audio transformers by Rod Elliott.