Is this how a Subwoofer Crossover is supposed to work?

Hey OP,

Don’t be so upset about the Klipsch yet! See the dip around 28 Hz? This is a typical close mic measurement of a ported speaker. This is normal. Ideally you also close-mic the port, and sum the two together which is somewhat complicated math to do right. For more on this, see D’Appolito’s work, Testing Loudspeakers. 

As you move the mic away from the sub, the rear port contributions will come into play, but so will the room. Unfortunately this is how we have to do it to get quasi-anechoic measurements of ported speakers.

Next, you are right, the Starke is pretty flat, but the crossover is not doing what normally you’d expect. The THX standard, which many try to match, is a 4th order low pass filter for the sub. This helps match with a main sealed speaker that has a 2nd order high pass applied. As Duke has previously noted (and looked through the messy data) this looks somewhere between a 1st and 2nd order low pass filter.

Instead of changing the crossover frequency, you are changing the slope, and in all cases you are left with a rather low Q factor for the filter. A bad thing, meaning the filter’s effects are visible almost down to 20 Hz no matter what the setting is.

So while I like the speaker curves overall, the built-in crossover is a coarse beast. Definitely get a miniDSP and leave the sub’s crossover "wide open." You’ll be able to not only execute a 4th order low pass filter at any Hz, but you’ll be able to clean up some of the anomalies and add millisecond level delay to the sub, allowing you to perfectly phase match with your mains.

Also, please note how much better this is than your original measurements. Now that you can see how well it does, you know what to shoot for. :)




Best,

E

@ OP
Check out ieLogical SubterraneanHomesickBlues for a little information on setting up subs and how their controls work.

Definitely characterize you subs individually at close range and in the same position.

Visit hunecke.de | Loudspeakers Calculator and input your room. Do the same in REW.

Sadly Starke doesn’t give any sensitivity for Bal/UnBal, or much of anything else. I couldn’t find a Willsenton R8 manual.

Using BAL to the Sub and RCA to the R8 will have about 14db more gain to the subs, assuming the DAC uses industry standard levels. If the DAC does not have a level control, the subs are being driven an unattenuated signal.

Note that the SW12 has an insufficient control set to integrate well except in possibly a single location.

Except for the name calling this has been an interesting thread. I've learned several things.

I realize that I'm not answering your question but I would like to take a step back and look at this from another angle.

1. Your Moabs are spec'd to 20 hz. I've never heard these speakers but they have great reviews and I've never heard anybody say they are shy in the bass.

2. You purchased two subwoofers which cost $350 each and weigh 40 lbs. to supplement the bass of a pair of full size, full range, highly regarded $4500 speakers that reportedly compete with speakers costing 10 times their price.

3. If the Moabs go anywhere near 20 hz you don't need subwoofers. If pipe organ is your favorite type of music and you are missing the 16hz notes then you could spend several thousand dollars on a sub that would not only go that deep but was equipped with a high quality crossover that included a very low cutoff point. Wilson makes a sub for $40,000 that accomplishes this purpose.

4. The subwoofers you bought are accentuating the frequencies that your Moabs are already putting out. They are doing nothing constructive.

5. If I understand correctly, the subs have no speaker input and no speaker output. In my experience cheap subs are usually designed so that you hook your speaker wires to the sub and the sub crossover sends the main speakers the high pass signal. That prevents the sub and the main speakers from doubling the bass frequencies. It looks like these subs are designed for folks who have small stand mounted speakers that have their own natural rolloff at 60 hz or higher. It's pretty obvious to me that they were never intended to integrate with a pair of full range speakers like the Moabs.

The lesson here is that your subwoofers are doing more harm than good. You are just adding low frequencies that your Moabs are already supplying. If they sound bass shy then it's likely that your room is the problem, not the speakers. It's probably not feasible to return the Sparkes but you should have devoted that money to room treatment instead of subs.

I can provide an example of a subwoofer/full range speaker setup that is working well. I have a pair of Thiel CS6 speakers that are rated to 28 hz on the low end. The bass is great but it is lacking in the lowest octave. I also have a 15" Velodyne subwoofer that incorporates a pretty steep crossover. It is adjustable down to 40 hz. I use the Velodyne with the crossover at its lowest setting. About 80% of the time the subwoofer just sits there looking impressive but not making any sound at all. But when I put on something that has low bass it gracefully adds the gut jiggling frequencies that the Thiels just can't reproduce. But this didn't just happen. I've spent a lot of hours on speakers placement to get there.

Sorry to be sarcastic, but if you think your Moabs need a pair of $350 subwoofers to sound good than you should seriously consider returning the Moabs, not the subs.

This is why I purchased two REL S2 SHO subwoofers.  They use a high level connection to make their subwoofers act as lower end subwoofers to extend the bass on the main speakers.  If you set things up correctly, you won't hear their subwoofers over take your main speakers.  I have the volume on my REL's set at about 40%.  They are smooth and seamless.  I wonder if REL has a patent on this technology?  If not, can't understand why other subwoofer manufactures aren't using this as well.  If you have not auditioned REL subwoofers you need to do so.  As with everything else, main speakers and subwoofers need to positioned correctly to receive the best sound. Be curious to hear what others in this group feel.