Electronics 2000

I have an audio system that is asking for a 15Kohm to 15kohm isolation transformer to isolate between balanced and unbalanced audio sources. Is there any difference between say a 10k to 10k or 100k to 100k? Aren't they all a 1 to 1 ratio so it is irrelevant? So far, all of my local supply houses have given me a funny look when I ask for this device. I fully thank anyone and everyone that can answer these questions and bonus THANKS to those that can tell me where to get such a device. I am located in Wisconsin, US of A. Thanks!

when you are looking at any amplifier or any audio device for that matter, you have to take into account for input and output impedance. the effect this has very much depends on the amplifer type used, but this can mean the difference of to high or low gain on the input/output.
This is because the input resistance can act as a potential divider, changing the input resistance away from the designed value will either increase or decrease the P-P voltage applied to the amplifer, which could at best mean a lower P-P voltage at output, but at worse either a clipped output signal or even blown input stage.

also from a more complicated view point a poorly choosen transformer can decrease sound quality. if the capacitence/inductance/restance bascially any electrical chariteristic differs this will effect the way the signal is reproduced. if you plotted the voltage over frequency with different transformers each graph could show gain in differnet frequencies outside of the intended design.

hope this helps and im sure theres alot more i havnt said, but this is just off the top of my head. google input biasing. plus see if you can find out what class amplifer your input stage is and what type of semi-conductor is used in it.

10K to 10K should close enough for most applications. DigiKey.com has several candidates, 237-1118-ND is the least expensive. If the device the transformer is feeding is really 15k adding 30k in parallel would bring the transformer loading to 10K but that probably isn't necessary. You could experiment with the resistor value for the best sound.

John from Minneapolis