Originally Posted by Kevin_Hsu
Sorry for the late response! I saw that there was a response but for some odd reason I wasn't able to find it. When you say you are trying to smooth out the response, what aspect would you like to smooth out more do you need more present mid-bass?
Not really, I was just wanting more even bass response overall.
I ended up placing a single TN in the front left corner, one in the back right corner, and the VTF-15H Mk2 in the left rear corner of the room for now. I will probably play around with the position of the subs in the rear of the room a bit, but the overall response after time aligning and EQ is pretty darn good now.
I went from ~8.5% THD peak at 17.3Hz with just TN's in rear corners to 2.3% THD at 10Hz peak with 3 subs in their current locations, and under 1% THD from 15hz up. That's at my usual -15dB listening level. I'm VERY happy with that.
I had to turn gains down on the TN's from ~11:30 on the 500W amps to ~10:00, and have gain knob on the VTF at about 08:00. I did run a sweep at reference level, and see ~15% THD at a few spots, but under 10% most of the time in the audible range (at reference, with just TN's It was 30%+). So, I got more extension, flatter response, and lower distortion.
Overall, I'm quite happy. I may boot up my computer into windows (ick), and try Multi-Sub Optimizer and let it run overnight to see what brute force computation can accomplish as far as flattening the in-room response.
All graphs are with no smoothing applied... and the rising response as frequency drops is intentional with a house curve.
For settings on the VTF-15H Mk2, I have it at EQ1, Q 0.7, 1 port open. I did not try any other settings on it. That's a job for another day.
On a side note, the VTF is big, and heavy. It's also quite well built, the satin finish is immaculate, and the grille makes no noise. Hats off to Dr. Hsu for another subwoofer done quite right.