Audio Transformer Basics

[barefoot]

Ok, I'm totally new to the whole audio transformer thing. And I'm trying to understand the interaction between input impedance, output impedance, turns ratio, DC resistance, load, bandwidth, etc. Can anyone point me to a reference of some sort? All I really know is that the impedance ratio equals the square of the turns ratio.


For example, how do the primary and secondary impedances relate to input and load impedances?

So we have this general situation:

Input Impedance -> Primarily Impedance ] Turns Ratio [Secondary Impedance -> Load Impedance

Ok, then what would be the difference in input impedance between these two specific situations?

 Input Impedance -> 100k ] 10:1 [ 1k -> 1k

and

Input Impedance -> 10k ] 10:1 [ 100 -> 1k

Make sense? Also, how are the bandwidth and damping affected?

Sorry if my questions seem dumb or nebulous. I've built circuits based on Jensen application notes and they work great, but I really want to get a deeper understanding of how transformer circuits are actually engineered.

Thanks!
Thomas

 

[bcarso]

Check the meta-meta in The Lab. CJ's lists are helpful and the Elliot article might be a good start.

 

[pucho812]

Radiotron Designer’s Handbook chapter 5 IIRC. thats the one on transformers...

 

[ruairioflaherty]

Hi Thomas,

the best information I found when I was trying to understand this stuff is all on the Jensen site in the app notes section. Check out the big 13Mb file in particular. There are several pdfs there which go through all this stuff in detail and make it understandable.

I have the Radiotron but find it heavy going.

Best of luck,
Ruairi

 

[rotation]

Hi Thomas, i was in the same situation not long ago and CJ's writing in Meta and threads cleared many many things. I find Elliot's stuff a bit complicated and not so much pro audio related.

 

[barefoot]

I read the Whitlock papers on the Jensen site. Then I built some of his equivalent circuits in LEAP (loudspeaker design software). This has really helped me get my head around it. I'm a big fan of using modeling software to get a deeper "gut" understanding of these sorts of things! Now I feel a lot more confident about using transformers.

Thanks,
Thomas

 

[CJ]

err, Transformer Meta?
Buy one book, thats all you need, tells you more than you will ever need.
That would be Grossner.
He is in the Meta.
cj

 

[barefoot]

[quote author="CJ"]Buy one book, thats all you need, tells you more than you will ever need. That would be Grossner.[/quote]

Amazon.com
1 used & new available from $581.24 :shock:


But I found the reprint here for $75.

 

[CJ]

keep looking, s/b about 25 to 50 max , not a big glossy book, so should be cheap.
also at good college libraries