Crossover Resistance/Impedance

[trem]

When measuring DC Resistance of a speaker with a crossover (PA Speaker, Leslie, Hi-Fi Speaker) what exactly does the meter see.?
That is to say, if you put a DMM on the speaker jack connectors of a two-way (or 3 way) speaker, how does the crossover and tweeter get figured into the mix.?
If the meter says 6.9 Ohms, and the woofer is 8 Ohms, how does the crossover get read by the meter.?
Hope you understand what I am asking.....
Thank You

[Richard]

Most crossovers that I am familiar with are LC networks. The L is an inductor which has an impedance that increases with frequency. The C is a capacitor that has an impedance that decreases with frequency. The inductor passes signal to the lowest frequency driver, the capacitor to the highest frequency driver. In a more than 3-way system there are inductors and capacitors in series that pass a band of frequencies. If everything is working properly you are measuring the DC resistance of the inductor and low frequency driver in series but I don't think that an inductor has significant DC resistance.

[R.G.]

This is one of those questions that seem like it ought to have a simple answer, but doesn't. In general, crossover networks are extremely variable. They are not a single circuit with variations on the component values.

An incredibly simple one will have one inductor in series with the low frequency driver and one cap in series with the high frequency driver. I have seen examples with several each caps and inductors. So the answer is "it depends on what the crossover network is, and what the inductor resistances are".

For the simplest case of one inductor, one cap, you'll read the sum of the inductor resistance and the speaker DC resistance. Speakers also vary in their DC resistance. Eight-ohm speakers tend to be about 6ohms, give or take some. A well designed crossover inductor has to have a resistance much smaller than the speaker's DCR, otherwise it's eating a big fraction of the output power without making any useful sound. So a reasonable DC resistance for a simplest-case crossover would be the speaker resistance plus a little. The caps would block DC to the high frequency drivers. But that's about all you can say without knowing the crossover network.

[trem]

Yeah.....that sure makes sense.
I was "simply" wondering what a meter is actually telling you when you put it across the terminals of a speaker cab with a crossover in it.
Thank You

[Jazz P Bass]

The meter will more than likely 'see' the speaker resistance in parallel.

[Leo_Gnardo]

Yeah.....that sure makes sense.
I was "simply" wondering what a meter is actually telling you when you put it across the terminals of a speaker cab with a crossover in it.
Thank You

You'll be reading the DC resistance of woofer voice coils, with any crossover low-pass inductor in series. Anything "on the other side of" hi pass capacitors, won't be seen by the meter as you're ohm-testing with DC.