Online crossover calculator - in reverse?

Hello useful people. I've been trying to work out what a pair of crossovers I have actually are. It's not really important, just for curiosity and knowledge because:
A - I've never once regretted hoarding a piece of audio gear.
B - I'm curious about crossover design and know I'm going to have to tackle it one day.

There's lots of crossover calculators online, enter your speaker specs and desired crossover type/frequency, and get a schematic.

Are there any that work in reverse? No luck googling so far. I can read (I think) the values on all the components, trace the signal path, all that mess, but I'd quite like to know what they actually are.

So, short version: Any sites out there were a body can enter the components and signal path of an already existing crossover and be told what it is?

Thanks in advance to anyone with any ideas:)


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Oh well, that's probably a crossover for car. Why ? Because it has those screw-on binding posts! Am I right?
The answer to your question is not straightforward, because: the crossover works on the electrical side, but the final acoustical side is what matters. So, same crossover "pieces" might yeld ( and sure they do) to different "response" to different speakers, because each speaker has differing construction/design parameters.
The values you may find bidirectionally <normally and in reverse, see the title> get you in the ballpark, since the drivers are nominally in that Z range, have their application written on the box ( woofer, tweeter, midrange) etc.
ANd...the following posts will tell you that you have to measure with microphone, apply Fourier Inverse, use computer programs to calculate crossover components, box size etc etc.
I've been trying to work out what a pair of crossovers I have actually are.
I'm not aware of any 'reverse' calculators.

The first thing to do is to look at the physical crossover and try to establish what 'order' it is (1st order, 2nd order, 3rd order or 4th order).

Before taking this any further, allow me to check if you are aware of what order the crossover in your photo is. Do you know?
The idea is to find out the values of those two inductors, Tim.

Using a simple second order, two way crossover calculator like this one ERSE - Crossover Calculator - Second Order 2 Way will throw up the values of the inductors - provided the correct individual impedances of the bass and treble drivers are entered (and after you've jiggled about with the crossover frequency of course).

I think the capacitors on the board are 6.8uF and 4.7uF. If I enter a high pass impedance of 6 ohm, a low pass impedance of 4 ohm and a crossover frequency of 4000Hz into the above calculator, I get calculated capacitor value close to those standard values - and, crucially, the two inductor values.
Wow, quite the response to this. Many thanks, there's a hell of a lot to think about here. This looks like it could be interesting.

I should give you an accurate level of my knowledge: You're dealing with a beginner here. Imagine someone who's watched a hell of a lot of teardown videos on youtube, googled a few things here and there, fixed the odd basic/obvious problem, and that's pretty much me.

These simple looking little circuits piqued my curiosity and I would rather like to see if I can gather just enough knowledge on the subject to one day be able to make a total mess of designing and making a crossover I almost (but not quite) understand. I guess they just look like a good place to start the learning process.

It's late and I'm about to nod off but I'll quickly pop through a few points before sleep takes me...

Yep, they're from a car - salvaged parts from a wonderful machine I wish I hadn't scrapped.

Unfortunately I have no idea what an order even is in terms of crossovers... I'll have a google on the subject in the morning but the short answer is nope, no idea.

"...keep entering frequency till the calculator spits out..." Interesting! An angle of attack. Nice. More sunday morning fun.

And yes, as hoarded parts basically my requirements, well, I don't know if there are any actual requirements... It's just pure curiosity and an opportunity to learn a little. Maybe even figure out enough about them that one day they could come in handy as a temporary bodge-up while I learn how to make the right crossovers for the imaginary bookshelf back room speakers i'd really like to make one day.

A good long google and read/watch/whatever on the subject is on the cards it seems.

Again, thanks for the response to this!



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Trace the circuit. It's no more complicated than a subway map.

Car-sound is usually 4 Ohms. Do you know any reason this might be wrong?

With the plan "any idiot" can plot the nominal response on resistor load.

Or heck: connect it between a power amp and a couple 4 Ohm resistors, sine-sweep, measure level at both outputs.

My 2 cents says "about 5kHz". It crosses between a "full"-range and some small tweeter.
Unfortunately I have no idea what an order even is in terms of crossovers... I'll have a google on the subject in the morning but the short answer is nope, no idea.
So my suspicion was correct, you don't know a crossover order from a fast food order! :D

Yes, some prior research is required! Since you're familiar with car audio,you may find this a suitable resource: Basic Car Audio Electronics

(See Section 91 and other associated sections.)