It's a custom product as most Monolith products are of a ground up engineering and design.
FWIW, Designed by Dan Roemer, Claridy Audio and myself... built in the same factory as the Monolith subwoofers & Perlisten. All the good stuff is probably Dan, all the bad stuff is probably me. ;)...
We did measure more output across the frequency range of around 0.7db to 1.2db on the V2 subs versus the V1 subs. However, I felt this is within the variance of measuring on different equipment on different days, so I posted the measurements for the V1 subwoofers as to not overpromise anything...
It was all about demand. The sealed just didn't sell in enough numbers to keep around. I assume it's because you can make our ported subwoofers sealed by using the port plugs, and no one really cared enough that the sealed subwoofers were smaller.
It's obviously a grand conspiracy and I want only the owners to understand all the HTP-1 secrets. ;)
We should have the online manual updated and sometime in October. As I've stated before, the manual and help guides that are built into the HTP-1 interface are fully up to date.
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Unfortunately, we have been adding too many features to keep it up to date. We will publish a newone in October, that will need to be updated once DTS X Pro gets added, etc.
The good thing is the manual that's built into the unit is up to date with all the latest information.