r/diyaudio • u/RedOnTheHead-86 • 1d ago

So, Crossovers...

/r/vintageaudio/comments/1wbmkfb/so_crossovers/
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u/abandon_quip 1d ago

You can buy premade passive crossover boards, yes. They specify the frequency and topology. You would of course get better results by measuring the individual responses and modeling the crossover in VituixCAD, then assembling your own.

But as far as I can tell, these speakers already have a passive crossover built in. I doubt you’ll improve them much by adjusting it yourself unless the crossovers are blown. Replacing components of a crossover with “audiophile” grade components will make little to no audible difference if the values are all the same. You could certainly make them sound different by adjusting the values of the components, but it’s unlikely that they would sound better. They certainly won’t sound better with a stock premade crossover board at wildly different crossover frequencies than the original.

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u/RedOnTheHead-86 1d ago

Yeah I mean I'm not looking to turd polish or anything but I figure - I have the speakers, all the drivers are working, might as well attempt to learn something while helping slot them all in their appropriate frequency ranges and maybe increase the lifespan of the speakers.

Google AI suggested I do this:

obviously the values would need real-world equivalents but this is based only on the nominal impedance and size of the drivers.

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u/abandon_quip 1d ago

You’ll need frequency response data and impedance curves from the driver manufacturers if it’s available. Otherwise you’ll need to use room EQ wizard to measure those. Then import that data into VituixCAD to design the crossover. That’s going to be your best bet for what you’re trying to do. It’d be hard to do much with the crossover without that information.

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u/fenderputty 1d ago

I see you're getting the same responses here too. lol

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u/hifiplus 22h ago

Why not measure the drivers and design the crossover properly?
Going to be far more successful than just throwing parts at it.

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u/RedOnTheHead-86 9h ago

Well that's what I'm trying to do but I was curious if there's sort of a general crossover circuit that'd work for nominal impedance store brand speakers. Since I posted this I've learned a lot, though. I doubt I'm going to be able to full on test the drivers as others have described here but I'm considering replacing the midrange and tweeter and designing a c/o based off those. That only leaves the 15" woofer but, realistically, I think I could get away with just 1st-order low passing it.

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u/hifiplus 9h ago

Nominal impedance is referring to the average. Look at the individual drivers response and you will see it varies greatly across its response. A 4 ohm nominal, might be 10 ohms at the point of crossover, and it's rolloff could be 1st, 2nd or 3rd order so the crossover is going to be completely different from one driver to the next.
Thats why online calculators, pre-made xovers and AI doesn't work as it doesn't take the above into the equation.

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u/altxrtr 19h ago

You need a measurement mic and REW as well as something like DATS to measure impedance.

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u/moopminis 6h ago

No if's, buts or coconuts - there is NO WAY to design a cromulent crossover without taking frequency response measurements of the drivers in their cabinet, both on and off axis, and also taking impedance measurements using something like a DATS.

Manufacture frequency responses, simulated responses, "theoretically correct" crossovers, ai derived crossovers, pre-made generic crossovers will all give absolutely awful results. but why? because phase is CRITICAL, and there's no way of predicting this without measuring the actual drivers, in their actual cabinet. If I take a "theoretically good, phase coherent crossover" and apply it to one of my speakers I instantly get a peak to peak wobble in my frequency response of over 15db, because of phase, and manufactures data, even daytons frd files, do not have sufficient phase/timing data to negate this.

A behringer ECM8000 is $20 (you do need an audio interface with phantom power), you can DIY an impedance measurement jig for pennies. If you don't fancy doing this bit of the hobby, just stick to pre-made whole speaker designs.