Is this how a Subwoofer Crossover is supposed to work?

In my opinion a good starting point would include seeing what the sub itself is doing without the room’s effects. Since this is a sealed-box sub, this will be fairly straightforward.

Measure the sub’s output with the microphone about 1/2" from the center of the cone. This is called "close-micing". The output from the cone will much louder than the room’s reflections at the microphone location, and will essentially overwhelm the room’s effects.

The difference in shape between that curve and your normal in-room curve is what the room is doing to the sub’s response.

Speaking of differences, the differences between your 50 Hz, 90 Hz, and 130 Hz curves look to me like they are "in the ballpark" for a 12 dB per octave crossover. The 50-Hz feature you are identifying as the "crossover point" is probably either a room interaction effect, a frequency response anomaly native to the subwoofer, or both. Having the close-miced curves in addition to your in-room curves will give you valuable insight into what is native to your subwoofer and what is caused by room interaction.

Pinwa, you mentioned that you are using two subs. Two subs can work together to give smoother in-room response than either one alone. How much freedom do you have to re-position your subs?

I disagree with Erik’s statement that "if you can’t integrate 1 sub, you can’t do2. " As the number of intelligently-distributed subwoofers goes up, not only does the in-room response become smoother, but the specific location of any one sub becomes less critical.

Duke
subwoofer designer and manufacturer

Kenjit,

We are all still waiting on you to post a blog post with details on anything you've bought, built or improved.

You are able to attack me only because I publish excessive details on what I've made.

Your only contributions to this forums have been random and self-contradictory theories with ZERO factual information.

Is this the week you believe in engineering, or the week you don't? Does that change hourly for you?

Best,

E

Pinwa,
Thanks for posting.
Curious. Did you mention what amp you are using?

I disagree with Erik’s assertion that "if you can’t integrate 1 sub, you can’t do 2. " As the number of intelligently-distributed subwoofers goes up, not only does the in-room response become smoother, but the specific location of any one sub becomes less critical.

Hi Duke,

I don’t disagree that things get smoother, but if you don’t know what 1 sub will behave like, you have no idea of the second is making things better or worse.

Attempting to set crossover points, and delays for both subs at the same time is a lot of work. Far easier to do after you’ve gauged the overall response of a single sub. The FR response of the OP using two subs was, I think you’d agree, pretty awful. Seeing a single sub’s FR would clarify much.

However, it is clear to you, and other experts that 2 subs are better than 1.  :)

Best,

E

pinwa,
First, congratulations on the Moabs. How long you had em? Should sound real nice with that Willsenton. KT88 or EL34? How's it sound? Aside from the subs I mean. 

Sounds like your problem is the line level from the DAC is high enough you're not able to attenuate it down to where you want it. If the Willsenton had RCA pre-outs that would be ideal. Doesn't look like it does. So your solution would be to do like I did with mine and create a pre-out by using what is called a Line Out Converter or LOC.   

An LOC is nothing more than two resistors that serve to drop your amps speaker voltage down to line level. Here is the circuit https://www.epanorama.net/circuits/speaker_to_line.html 

If you remember my Melody amp didn't have pre-out either. What I did was modify one of my extra unused RCA inputs by adding the two resistors to turn them into a pre-out. You can see a photo of the mod on my System page https://systems.audiogon.com/systems/8367 Its not much, very simple. Total cost for the 4 resistors was just under $2. 

If you don't want to mod your amp (its easily reversible btw) then you can make your own LOC for $2, connect it to ordinary speaker wire, put an RCA on the end and plug it in. Or buy the cheap one from Parts Express. Same result either way. This should totally solve your problem.