Is this how a Subwoofer Crossover is supposed to work?

"Please do [elaborate]..."

"First order" means "6 dB per octave". "Second order" means "12 dB per octave. "Third order" means "18 dB per octave". And so forth.

I made a mistake and mis-read the vertical scale. Upon closer inspection, the slopes I’m seeing are closer to 6 dB per octave than to 12 dB per octave.

For the moment let’s focus on the SPACING between the the lines on the 50 Hz setting, the 90 Hz setting, and the 130 Hz setting. The change in the spacing between the curves will tell us what the different crossover settings are doing.

Over the octave from 50 Hz to 100 Hz, the spacing between the 50 Hz and 90 Hz curves grows by about 4-5 dB. This is about what we’d expect from two 6 dB per octave ("first order") filters that are less than an octave apart (90 Hz is less than one octave above 50 Hz).

Over the octave from 50 Hz to 100 Hz, the spacing between the 50 Hz and 130 Hz curves grow by about 7-8 dB. This is about what we’d expect from two first order filters that are a little more than one octave apart (130 Hz is more than one octave above 50 Hz).

Okay, now let’s stop overlooking the ups and downs in your measurements. The rolloff certainly LOOKS LIKE it begins at 50 Hz regardless of the filter settings.

What we don’t know is, what the response of the subwoofer is WITHOUT the room. For instance, that EXTREMELY steep rolloff between 50 and 55 Hz looks to me like a room interaction effect.

But the general trend over the two octaves from 50 Hz to 200 Hz is a significant amount of rolloff, so I SUSPECT that’s in the subwoofer’s native response. Mentally subtracting out the crossover filters, it LOOKS to me like the native response of the subwoofer is rolling off at ballpark 12 dB per octave north of 50 Hz.

ONE possibility is that the subwoofer’s voice coil has very high inductance which results in significant peaking in the 40-50 Hz region, followed by a lot of rolloff above that region, due to inductance or cone mass or both. (A very high voice coil inductance can easily happen in a subwoofer driver, resulting in a response peak like what we MAY be seeing in the 40-50 Hz region, followed by an inherent rolloff like what we MAY be seeing north of 50 Hz, but without a close-mic’d response curve we cannot reliably say what is room effect and what is not.)

So I THINK your subwoofer’s crossover is working as designed. I THINK that the response curves you are getting are a combination of the native frequency response of the subwoofer, the effects of the crossover, and room interaction.

Duke

LImited knowledge but I have used subs and feel I get some reward.  I have used successfully small cheap ones for computer, kitchen and better one's (REL) for main.  Some main speakers do better than others with sub.  My old KEF's are a bit slow in the bass and the sub can accentuate it.  Most of the time I find keeping the role of the sub subtle is better.  A touch of bottom, warmth, fullness but not a lot. My new speakers (Sonus Faber) are cleaner down to where they stop and I find that easier to get the bass in there improved without drawing attention to itself   Images again are bigger, deeper, fuller.  But the key for me is a light touch.  I agree with those that suggest one at a time.  Placement and settings very key  And in the end one setting might not give best results on ALL music I settle for the settings that provide SOME benefit but least annoyances.  

ONE possibility is that the subwoofer’s voice coil has very high inductance which results in significant peaking in the 40-50 Hz region,

@audiokinesis

I think your characterization, that this sub is rolling off far too soon is spot on, which is why I suggest removing confounds. :)

There is some great information here, but this thread REALLY has me wondering if I want to mess with subwoofers!