Level matching when using active XO.

[Saurav]

I have a CX2310 on its way, replacing a hacked-up DIY XO that I'd been using. What's the best way to correctly level-match the two amps/drivers? I have a laptop, mic and preamp. Should I buy a higher resolution version of TrueRTA and use that to balance the levels with pink noise? Any way I can do this using Speaker Workshop or Room EQ Wizard?

Thanks,
Saurav

[ThomasW]

I have a CX2310 on its way, replacing a hacked-up DIY XO that I'd been using. What's the best way to correctly level-match the two amps/drivers? I have a laptop, mic and preamp.

You could use the individual level controls on the crossover....... :B

Okay just teasing ....:wink:

This is a situation where trusting one's ears comes in to play. Sure take a look with a measurement program, but in the end adjust the levels to what sounds best .....

[Saurav]

Well, I have pretty different gain/power/sensitivity on both sides of the XO, so I'm pretty sure keeping the highpass and lowpass at the same level isn't going to work.

Though I like the "fiddle until satisfied" approach. Wait, that didn't come out right...

[ThomasW]

I don't know what rez level you have of TrueRTA, the free version won't work for this but even the 1/3rd octave will give you what you need. If you have the higher rez level with the quick sweep that would be nice for more than just this project.

[Saurav]

Well, I have the free version, but I've been thinking of buying the 1/3rd or 1/6th octave version for a while now. I can record pink noise and tone sweeps with Speaker Workshop too, but that becomes a very snapshot-y process, it's certainly not real-time.

So with 1/3rd octave resolution... should I use a tone sweep or pink noise? Frequency limited to around the XO region, or wider? Mic positioned at listening height? And I read something about pointing the mic at the ceiling when doing RTA measurements?

Thanks for the help

[ThomasW]

I think the sweep is only included in the $99 version. The sweep itself is pink noise done quickly to avoid room interaction.

I'd start off with mic relatively nearfield, 6" or so from the baffle. The look at the 1-meter response.

[Saurav]

Thanks. That makes sense. I was measuring from way out into the room. Though the woofer is in a box and the midrange is on an open baffle This'll be fun. I'll probably tweak it by ear in the end anyway, but at least this'll get me in the ballpark.

[Mark Seaton]

Ideally you would want to take the speaker, amps and crossover outside and do the level matching there with TrueRTA. Taking a few measurements to highlight different interactions can piece together a good picture of what is going on. A typical measurement on-axis outdoors will inevitably have you dealing with the ground reflection. Take this at two different distances for a first point of reference and to get the drivers in general proximity of each other so far as level.

Now on hard pavement prop/angle the speaker downward and find the location that your intended on-axis point hits the ground. Get the edge of the mic within about 1/4" of the ground, and now take some measurements. You will have some added hash above the tweeter's crossover, but you now have gotten around the problem of the ground reflection and can work with more readable curves when adjusting relative levels. Again the point here is to set the relative level, so absolute levels really don't matter. In room you will have some other things to contend with, but at least you know where you are starting from. Likewise, you can then know that what you are adjusting for is an acoustic issue and is something you might want to try addressing directly rather than with crossover adjustments.