Ordered my UM18 today (thanks
for sharing the coupons!)
I've been getting to know REW and the UMIK-1 a bit this week. I'm pretty excited, I got some great numbers and graphs. Tons o' fun.
Set up in Main Listening Position:
First up just a couple of frequency response curves from my very first set of runs:
was first with L&R running full range (apparently I had left the bass boost at +2 at the receiver).
was next with the subs and LR crossed over at 100Hz.
I know there's a lot going on here, but these are completely preliminary (with 1/6 smoothing, not L and R separate then averaged - I learned later that would have been better). Some pretty obvious ~50Hz mode boosting and lots of room gain below that. Also cancellation or something between 50 and 100 with subs and fronts. Weird. (gain on my MBM is set pretty low for these runs)
My next test was to see what my MBM is helping or hurting with. I did about 8 runs with the MBM set to various gain settings. This graph shows the two curves that mattered most to me.
is with the MBM off (gain set to 0)
is with the MBM turned up to 75% (15 out of 20 notches on the iNuke)
Nice. I was worried I had set the MBM too high but it turns out I was much too low. I kept it around 6-9 notches on the iNuke so 30-40%. You can see matching to the subs required 15 notches - 75% gain on the iNuke.
Last but not least was to do the FR test of the MBM (one of the main reasons I broke down and got the UMIK)
First I tried an in-room FR with just the MBM at 1m distance on the floor in the living room (lots of boundaries and room modes) this is about the least useful graph
I produced today. (I want to do another indoor test with the mic close the sub instead of 1m away to see how close I get to my outdoor graphs below - problem is you've got the port and the driver and averaging the two)
Update - did the indoor test with the mic and the graph is nowhere near the outdoor graph.
Last I ran the MBM outdoors (ground plane). Here's the setup:
I built this box (~3 cu ft) with two ports with the intention to test and compare the two setups (high tune and low tune). According to WinISD: two ports = 54Hz tune, one port = 38Hz. Of course they are triangular ports so they will extend along two boundaries inside the cabinet which would drop the tune somewhat, so two ports = 49-54Hz, one port = 34-38Hz. There isn't much excursion around tune, so it was hard to tell by looking at minimum excursion what the tune was.
- I used the current measurements to find port tunes. Two ports = 46.5Hz, one port = 35Hz. Lower than I expected for sure. No problem.
So here are the two graphs overlayed:
= low tune ~35Hz
with one port open (5"x5" triangle, length 5")
= high tune ~46.5Hz
with two ports open (two 5"x5" triangles, lengths 5")
I think his is the most valuable graph
I got from my time today.
Here are the graphs from WinISD for comparison:
Next up I'll be cutting down my MBM box from 3 cuft to 2 or 1.5 cubic feet to do another response test for comparison (I thought about just throwing a bunch of 2x4s into the box to cut down the volume for testing, so I might do that).