Topic: Old-School Electronics Question:

[James]

What if I wanted to experiment with winding my own audio impedance matching transformers?

Let's say I wanted to be able to use a weird number of tweeters, like 13, either all in series or all in parallel.

I should be able to match the impedance with a 13 to 1 transformer, in either configuration. Correct?

My ultimate question is...

How would this work with a modern amp?

It seems to me that, at low frequencies, approaching DC, the impedance of the whole thing would be nothing more than the DC resistance of the primary coil.

What I'm trying to get is the most direct drive to the tweeters with no DC offset from the amp.

A transformer would solve that problem and also let me use weird numbers of tweeters.

James. 

[meandean]

 Transformers in principle are simple, but winding a suitable one on your own may be a task; there is actually a lot to it. Transformers are usually included as an integral part of the amp design, vs an add-on. Transformer based amps usually work in the DC biased domain on the primary side and kill 2 birds with one stone- DC isolation, and maximum power transfer between the amp and a fixed impedance load (keyword 'fixed'). Transformers are also useful for boosting voltage gain in a low signal level app (like a mic preamp) without adding much noise.

  You mentioned connecting drivers in a series-parallel fashion, so you have some control of the total impedance (yes, odd numbers are a slight balance problem, but what you get from a homemade transformer would probably be worse)- pick a config that best suits your amp, and throw in a series cap to block unwanted DC. 

[Fanny Pack]

I worked with magnetic amplifiers in the Navy.  They are basically transformers with several different windings.  One of the windings was to set the bias.  Another set the offset, etc.  They were pretty horrible but they did the job.