The 25 stands for the tuning frequency of the port (determined by length and diameter). When they say 25(22)-31, it means that the port is tuned to 22 hz. This has the advantage of somewhat deeper bass, but it costs in SPL. I don't know the exact figures, but as the 25-31 PCi is already so loud, i don't think an average person will miss it!
I don't own one, so can't say whether the difference is audible and worth the extension.
I have also seen this mentioned.....Does this "Custom Tuning" from 25 down to 22 cost extra?? If so, how much?? Is this done at the SVS factory before they ship out a new unit??
No cost if specified during the order process (just e-mail us). Current owners can actually get one after the fact but it costs $29. Not bad but not free either.
This sounds like the perfect solution for me. Due to space and SAF, I really need to get the smaller enclosure of the 25-31PCI. Also, due to my high propensity for music and my small room, the 25-31 made more sense anyway, but knowing I can tune it to 22htz for extra movie impact and only sacrifice a couple DB up top, really makes it the perfect tweek for my needs. I will be ordering one of these in the fall for sure as my next upgrade.
Blair,
The lower the Hz number the lower the bass. If you like to listen to pipe organs, then you probably want to consider the sub with the lowest Hz tuning - the 16-46. However, if you don't need to hear, or in most instances feel, bass this low, the 25-31 will work for you - tuned lower or not.
Your best bet is to communicate with Tom and Ron directly. They will be able to guide you into the sub that gives you the sound you are looking for with the layout you have to work with. Go to their website and drop them a line - they will probably respond faster than you think. Good luck!