Here is my initial test the other evening. I was mostly just trying to verify my UMIK + REW setup was working.
There's still no dampening in the box. I did throw a blanket in the bottom but that didn't seem to change much. Not sure there's much to really glean from this for now.
Wayne Parham Messages: 18793 Registered: January 2001
Illuminati (33rd Degree)
As expected, the trend looks right but there's a lot of "grass" from all the nearby reflections. All those deep notches are from interference with some object's reflection that's 180° out-of-phase.
The things we really need to know - and so we need an environment that's reflection-free enough to see - is we need to know what's going on between 100Hz and 400Hz and we need to find the vertical nulls which are around 1.2kHz.
Wayne Parham Messages: 18793 Registered: January 2001
Illuminati (33rd Degree)
Yes, you're working with much cleaner measurements now.
Get some stuffing in the cabinet and see if you can do anything with that peak around 120Hz. That is the difficult region I often talk about.
You'll notice the stock cabinet gently rises from 100Hz to 150Hz and then gradually drops to around 200Hz. This is the result of the positions of the midwoofer driver, port and insulation. It prevents the really big peaks and dips.
The peak in your cabinet is not unusual. I've seen a lot of cabinets like that. It doesn't sound terrible, but you do notice a throaty sound in male voices and other things. It just sounds "boxy."
So try lining the walls with insulation and also try placing a sheet that spans the cross-section of the cabinet between the port and the woofer. Might even use two of those. That cross-section "divider" sheet has proven to be the most effective, in my experience.
Wayne Parham Messages: 18793 Registered: January 2001
Illuminati (33rd Degree)
I would strongly suggest adding insulation first. Especially the cross-section sheet. Try it straight. Try it diagonal. Make sure you can mitigate that peak at 120Hz.
I say this because you might find that your efforts to damp the peak are illusive, and you might end up moving the port. This is best learned while you're still in the "cut and try" mode.
Wayne Parham Messages: 18793 Registered: January 2001
Illuminati (33rd Degree)
The response in the 100-200Hz region is about the same, so I think you want to look at things you can do about stuffing. Hopefully you can find a solution with damping material. Not sure what's going on above 1kHz, but it looks like there are a lot of reflections. Could be also way off-axis in the vertical, but that wouldn't explain the dip around 2.5kHz.
Posting Rules
Members
Search
Help
Register
Login
Get a T-Shirt!
