The Ultra-13 is a fine high output linear subwoofer and I have spent two long sessions comparing it to several other subs including JL113, Paradigm servov2, Velodyne DD-18 and EP600. My only concern with recommending it stems from the amp. While not everyone has experienced a problem with it the owner of the Ultra-13 has now had two new 750W Indigo Bash amps sent as replacements because of shutdown problems and amp clipping in certain demanding soundtracks.
To make a long story short the driver and enclosure would have been better served with a 1000w amp which would have minimized clipping and problems with impedance mismatching between the amp and driver. With the insufficient 750W powered amp and all the reports of shutdowns I can't recommend that sub. When it works though it sounds pretty good though port chuffing can be bothersome.
SVS was trying to make a price point and they compromised on what you can't see, the amplifier.
I hope you do not experience any shutdowns. The problem seems to occur in 10hz tune so if you run it in 15hz or 20hz tune you should be OK.
