impedance matching

[hydro]

hi
i have an audio amplifier with a 8-16 ohm output. i am looking for a way to make this output 50 ohms so that i may feed the signal through a band pass filter.
the signal frequency is 42.8khz if this helps.

have been told to get a matching transformer but havnt a clue what to get, have also been told a balun will do the job.

any ideas???

[5B4AJB]

A matching transformer and a balun are the same thing, you can make one by dividing the input by the output.
For example 50 Ohms divided by 12 Ohms equals 4:1 turns ratio, then, if you wound a transformer with 100 turns on the secondary and 400 turns on the primary, that would suit your purposes.

What you wind the coil on will alter the bandwith, Q, etc. The simplest former is a steel nail.
If you're building it for audio, you'll want good bandwith, for radio, narrow bandwith, high Q.