Those of us with the classic older Hsu VTF-2 sub-woofers know the story, that the amps tend to go bad over time (burn out or make noise), and as of around 2012, Hsu is no longer offering to repair the amps. Mine is making noise now.
Here is what Hsu Research now offers as a resolution:
"Unfortunately we no longer support that model. If you can enlarge the amplifier cutout about 0.1", you can purchase the VTF-1 MK2 amplifier and use that. It runs $215 plus $25 S/H if you are in the lower 48 states. The other alternative is since we do not support your sub anymore, we will extend you a one-time offer to upgrade to any of our new models at (special pricing)"
The following questions:
(1) Has anyone tried installing the new VTF-1 MK-2 amp? Results?
(2) Is there any 3rd party amp that can be tried?
(3) Hate to throw away the enclosure and speaker, any market for that?
(4) Most folks say it is very hard to repair circuit board even for a shop...it looks fine to the eye, no obvious blown capacitors etc
Now that I got the thing apart, replacing with the VTF-1 MK2 amp sounds workable from a wood work persepctive. The old amp comes out easily in a plastic enclosure, presumably Hsu would replace the whole unit and you would just need to make the hole a little bigger probably with a router. I never used the VTF-2 much over 5% volume but I like to get down to 25 Hz for good sound effects.