I have my second "H" frame subwoofer almost ready for paint.
H?
Just commonly adapted nomenclature.
If you look at the basic design from various angles, it is unique in that from the top the structure in line format the design resembles an "H."
My baffles are three thicknesses of 3/4 inch material sandwich - one plywood, one MDF, one plywood, which creates the center mass of the system. Quite a bit heavier than Linkwitz projects.
The "walls" see very little pressure and are only double, MDF on the inside and plywood outers.
Mine are dual fifteen inch, instead of twelves like he shows here.
He likes to add a lot of electronics to dipole systems for free air response to measure well, which I find unnecessary with proper room placement. Not disagreeing with a master, just still exploring other options.
To me it seems as if he is defeating some of the benefits to the dipole effect if you go messing with the natural air of these types of systems.
But, he's smarter than I am and has more measuring equipment. I have ears, some downloaded software, a few calibrated mics and one old O'scope.
Biamp and cross them over below 100Hz and you have a really effective addition to a bass shy fullrange Open Baffle driver.
With my new Lii Audio F15 drivers (which see), I intend crossing them off at more or less 42Hz, if the graphs mean anything.
The Lii Audio driver only reaches 50Hz with authority, but for some of my hard rock and even classical music, they need a helping hand.
So far, I have only used my H frames with my mono stack in the garage. They have not made it into the house as of yet.
I have no idea if they will mate well with my F15 Lii drivers at this point.
I have a lot of ways to try before I decide that it might not work, though.
This will be my fourth attempt at OB bass, but my first attempt at H frame type baffles.
What I had before with some back loading was awesome and I used them for almost fifteen years with the Visaton B200 drivers.
These Lii Audio F15 drivers are better in so many ways.
I took this from the Linkwitz website:
Notice his test microphone placement. I test my system from my listening chair, mostly, once I am done with "free air" or "half space" tests.
