I received the VTF-15H MK2 sub this week and it is gorgeous. I've been playing around with the tuning and thought you would all get a kick out of this: At first, I removed one foam plug and left the other in place as suggested for initial setup and configuration. Then I had to go out to run an errand. When I came back, my 9-yr old, who is just as excited as I am to have a new "toy", proudly tells me that he found a piece of foam packing in the bottom of the sub that I must have missed during the unpacking, so he removed it for me and threw it away! ;-). Luckily I could retrieve it out of the top of the garbage! After reinserting the foam and staring at it awhile, I decided that it does indeed look strange with such a beautiful cabinet and a piece of foam flush in one of the ports and the other port clean open. So I pushed the foam more into the port a few inches (the ports are deep) so that when standing and looking down, the foam cannot be seen. This looked much better. Hope that it's OK to shove the foam back a bit.
So, after about two days of testing all the tuning options with music and movies, I found that my favorite sound is achieved with the "sealed mass extension mode", 0 ports open, op mode to EQ1, and Q-control all the way to 0.7. I am replacing a 15-yr old Velodyne 18" sub, and for me, this mode on the HSU produced deep, smooth, room shaking bass during music and movie tests. In fact, my wife and son said, wow, this is much better & more powerful than the previous sub.
I had a few interesting things happen during initial testing. With one port open, there was some chuffing that occurred during the low organ parts of the Saint Saens Organ Symphony. I went right up in front of the sub when it happened, backed up the music and was able to reproduce the chuffing, I could feel the intense rapid bursts of air coming out of the one open port. Not sure whether I had my receiver sub output level too high (the sub volume was in the 9AM position), but the chuffing was there. Ultimately I found that my favorite sound was with both ports sealed, so I'm not concerned about this in my setup.
One other issue I experienced, when I turned off my system, I had a constant hum coming out of the sub (it was still on, set to auto power). When I unplugged the sub audio cable, the hum stopped. My sub cable is old and long (about 30 feet), but it is shielded fairly well. Perhaps it's time to try a new cable, the hum was there but very low volume w my old Velodyne. However, I found that I could turn on the crossover (switch set to in) on the sub and that stopped the hum immediately! So I left the crossover set to in and dial to 90hz (my receiver's crossover is set to 80hz). Problem fixed, but still not sure of the cause of the hum on the cable, as it would go away when I turned my receiver on.
Overall this is the best sounding sub I have ever heard in a home setup, especially in this price range. The tuning options are incredible, the low end extension is phenomenal and I'm glad that I turned to HSU when my Velodyne died its last death. (BTW, the Velodyne has been superb for 15 years, repaired several times for amp & servo issues, this time I just decided it was time for a new one).
Update: Replaced my old sub cable and no more hum when the receiver is off! So now I don't need to use the crossover.
Last edited by Jeffro : December 28th, 2014 at 6:45 PM.