Wayne Parham Messages: 19059 Registered: January 2001
Illuminati (33rd Degree)
That was a gated (fast) log sine sweep, often called a "chirp" signal.
My main focus was the crossover region, because I was looking for nulls. You can see them on the computer screen in the foreground when I move the microphone above and below the speaker. Watch for the notches to grow as I get close to the location of the vertical nulls, and shrink back when I get past them.
Got it. Yes, I am seeing a null show up at about 20 degrees above and below, around 1450 Hz. Looks fairly flat on-axis.
I hear a tiny bit of resonance with male vocals and acoustic strings in the middle range, how do I find the source of that? Not sure whether it's a standing wave in the cabinet or the 3DP ports ringing or what.
Wayne Parham Messages: 19059 Registered: January 2001
Illuminati (33rd Degree)
Excellent. OK, then, that tells us that the drivers are hooked up properly. Crossover is doing exactly what it is supposed to do.
As for the throatiness or resonance, I suggest a couple things:
1. Check your damping material. Make sure you added the sheet that spans the cross-section in addition to the ones that lines the walls. That cross-section sheet is extremely important because it traps the lower midrange better than the ones that line the walls. It should span front-to-back and side-to-side completely, essentially splitting the cabinet into two areas, one exposed to the woofer and the other exposed to the tweeter and port. Bass will pass right through but midrange and treble will not.
2. Explore the flanking-sub approach. The self-reflection from the front wall often manifests as a throatiness. It definitely causes a defect in the lower midrange if the speakers are anywhere near the wall.
You can also take the speakers outside temporarily or in the middle of a very large room to see if that's the problem.
If the problem is a bell mode in the port, you might try damping it with putty.
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