OK back to sharing the results of my recent audio tweaks:
What is making this fun is being able to see the low frequency room response in near real-time on the SMS-1.
The initial graph below seems to correlate rather well to my earlier REW attempts, especially that nasty null around 125Hz!
I had previously messed with changing the height and placement of my RF35 mains and observing with REW, at that time I found that I could somewhat minimize that 125Hz dip. So this past week; I experimented further while watching the SMS-1 to see if I could affect what was going on with my mains. One of the tests involved moving a roll of unused linacoustic around in front of the mains.
Although I didn't save the graph i could see on the SMS-1 that I was minimizing and shifting the frequency of the 125Hz null. I could also make similar improvements by increasing the height of the mains and pulling them about 12" further away from the the front wall. SO this was my test arrangement:
Below is the resulting graph after repositioning the mains. With repositioning alone; the 125 Hz null shifted to the left, and was reduced from a 13db did to about a 10db dip. The tape mark on the photo below marks the original excursion of the 125 Hz null.
I then went one step further; I raised the crossover frequency on my Marantz from 80Hz to 120Hz and then used the Velodyne slider to try and add some sub-woofer boost into the crossover area near the 120Hz null. The graph immediately above shows the affects of both efforts (placement and boosting the sub-woofers to help with the null). Both changes now appear to have reduced the 125 Hz null from 13db dip to about a 5db dip? I also diddled with boosting the 60Hz null (from 5 db to about 2.5db)
The one thing that I am becoming sure of is; that the original 125Hz null and the 60Hz null (also now boosted); are artifacts that are characteristic of my room. Side note; One needs to be very careful when trying to boost nulls; that one does not overdrive a sub-woofer, cutting the peaks is a better approach whenever possible.
I then diddled some more with a modest boost to the lowest frequencies, and then re-watched some of the my favorite low frequency movie scenes. The result brings a smile to my face
Next up: I need to revisit some measurements with REW to see my entire response from 10Hz to 20Khz