Crossover capacitors

[LewinskiH01]

1. Yes dats and wt2 are what you think they are.
1.2. REW should be fine, pretty sure if you measure and inductor or capacitor (in impedance mode) it will give a value in the bottom left corner of the graph.
SpeakerWorkshop will also work (it has a measure passive component function) with a standard impedance jig.
1.3. yes use REW or Speaker workshop (and probably ARTA as well) 🙂
2. I've only used enammeled copper wire, which was motor winding wire or otherwise known as magnet wire. Not sure about benefits of stranded wire.

Tony.

Thank you. For whatever reason I was under the impresssion Wolf was using stranded. Magnet wire is what I had in mind.

 

[AllenB]

So was I, for the bought ones.

I was under the impresssion Wolf was using stranded.

Do you have an oscilloscope and audio frequency generator? Alternately a resistor, capacitor and free analyser like HolmImpulse?

You are just trying to find their frequency of resonance. As long as the components are kept within their band (away from their parasitics), or in other words if you can get a capacitor to resonate with the inductor in, say, the audio band and the impedance peak is clear, accuracy of amplitude isn't critical.

Of course these days DMM based L meters are common.

 

[LewinskiH01]

So was I, for the bought ones.

Do you have an oscilloscope and audio frequency generator? Alternately a resistor, capacitor and free analyser like HolmImpulse?

I don't have oscilloscope.

You are just trying to find their frequency of resonance. As long as the components are kept within their band (away from their parasitics), or in other words if you can get a capacitor to resonate with the inductor in, say, the audio band and the impedance peak is clear, accuracy of amplitude isn't critical.

Of course these days DMM based L meters are common.

I'm looking at designing a 2-way xo at around 2500Hz, probably a 2nd or 3rd order xo. So I could do the design using commercially available capacitor values and let inductor values be whatever the calculation results, then buy the caps, then build the inductors using said caps to make them resonate at 2500Hz. Would that be it?

 

[wolf_teeth]

Thank you. For whatever reason I was under the impresssion Wolf was using stranded. Magnet wire is what I had in mind.

I use magnet wire in 14-18 gauge. TemCo on Ebay has a good supply of spools, and they are very cost effective. I've used about 6 spools of their stuff.

I do have a remnant spool (1500' when I started) of 18.5AWG Litz wire, which is made up of individually enameled and twisted strands. This is harder to make 'test spots' as you wind, as you have to solder-bond all of the strands to get your reading. I use a MetCal tweezer-style (meant for SMD) for the Litz. When this is gone, I will not likely use Litz again to wind my own as it is a lot more expensive to purchase than the solid-single-strand. I just happened to find a spool for sale second hand on line.

FWIW, I use a Mastech LC meter (~$50) to test mine as I wind, and if I want a calibrated sanity check, I use the WT2 to label it with a closer and tighter tolerance measured value.

In my earlier picture, I wound the 2 by the 1 and 2 support post dowels. The Litz coils there are sourced from Solen.

Later,
Wolf

 

[AllenB]

then buy the caps, then build the inductors using said caps to make them resonate at 2500Hz. Would that be it?

You're on the right track, yes.

A little more detail.. Sometimes the cap value for the test is selected to draw out the peak, just try it and see. Sometimes it is necessary to find the self resonance of the coil, which is where it resonates with its own parasitic capacitance at some high frequency and do the test well enough below this frequency. Also, some caps like worn out electros for example don't have a tight enough tolerance for accuracy of frequency.