Crossover Testing Methods

[papajoe]

Well I got the crossovers all done and need a way to safely test if it is working, other than hooking it up to the speakers. I have a oscope available.
Thanks,
papajoe

[jonpike]

Re: Crossover Testing Methods

Simplest, you could hook things up, hook to your amp, and CAREFULLY bring up the volume to a low level and listen to insure the low tones are coming from the woofer, and highs from the tweeter. At low volume, you won't hurt the tweeter if you've got it backwards.

Not much you can easily do with your scope to measure this. You'd need something to sweep, get some kind of F/V converter to create a swept timebase for the scope, etc... all to get the below result.

Better, put together a test setup for this (for this, just looping back thru the crossover, you don't even need an amp or special jig) you could use that to see if the responses are in the ballpark. Get REW or ARTA, or other free sw, and appropriate cables to hook up to your sound card, and send some signal thru the HP and LP... That would be a good check for any wiring errors, by being able to see a graph of the actual responses and if they're correct.

[Chris Roemer]

Re: Crossover Testing Methods

Never done this, but . . .

what if you just hooked up a DMM to each set of driver terms (off the XO) and checked AC voltage at 100, 300, 1000, 3000, and 10000 Hz (maybe off a CD, or PC wave generator)?

You should see a max within the pass band, half or less near the cross points, and little out of band.

Right?

[jonpike]

Re: Crossover Testing Methods

Yep, that would be manually creating a graph of the frequency response... point by point.
You'd want to take a lot more than those, but it's kinda tedious... And that was a way to do it back in the "good ol' days".

But, that's a great task for a computer... to measure a few hundred or thousand points in a few seconds, and draw it up in a nice pretty graph for you... especially when you already have a high resolution A/D and D/A device (aka, a soundcard) and someone else who wrote a nice program to do all that, that you can get for little to no money.

A couple of $5 cables, your computer with soundcard, and downloading REW... and you've got the equivalent of $3-5000 of customized gear, 15yrs ago..

Every now and then we should stop to think we've got it pretty good, nowadays... :D

[papajoe]

Re: Crossover Testing Methods

I downloaded a tone generator and using my DMM just checked for the whether the crossover was really working above and below the crossover points.

[PWR RYD]

Re: Crossover Testing Methods

You will need to place a load on the crossover outputs or your measurements will be meaningless.