Pairing Planar Speakers With A Subwoofer (Eminent Technology)

I have dual Rythmik F12G with Magnepan 3.7i's. I think subs, in general are hard to integrate. Make sure you level match each side.

Hi, Mitch. I bet what you were looking for was an opinion from actual owners of both LFT-8b and F25. Well, I’d be happy to chime in as a past owner of both products, at the same time.
Here is a link to my humble setup at a time , a couple of years back. As you can see , it was very modest. Nothing like yours. I was salivating at your pics. Those ARCs of yours nearly killed me!
Anyway. I can guess two possibilities.
1) You were trying to replicate, as much as possible, the looks of the IRS Betas with the Rythmik F25s. They kind of look like the bass towers.
2) You were trying to match the Eminents with the Rythmiks from their audio characteristics. The Eminents are exceptional speakers, but their bass response is rather underwhelming. Their beauty is in speed, transparency and Maggie-like openness and large imaging, without all the Magnepan drawbacks. So, you need a sub that wouldn’t be lagging behind. Before I bought the Eminents I researched which sub can be matched with them. The consensus was either a Rythmik or a Hsu. All others will create plenty of HT bass, but will lag behind with music. This wouldn’t matter to someone with a hifi level gear, but your equipment is a bit higher than that. Top notch. The loss of coherency between an HT sub and Eminent speakers will be obvious to you. Someone who shops at BestBuy that wouldn’t be as apparent, if at all.
May be you wanted to accomplish both, I m not sure. But let me tell you what I think. The F25 is an excellent sub. Plenty of power, very responsive, I loved the large variety of different settings in the back. You can adjust even the damping factor to sacrifice the bottom end in favor of responsiveness while listening to music. I cant say all these settings created any audible difference, but it was nice to know they are there. But over time I found the Rythmik still not being fast enough to play along with the Eminents and the Maggies (I had and played all three at the time). Over time I sold both the Eminents and the Rythmik (I had jut one F25). I found another sub that is sublime with music , provided you have a highly resolving speakers and all other gear (which you clearly do) and you are not a bass freak. The RELs are not boom-boom machines, they are designed to work for midrange. I was surprised to learn they are auditioned with purely midrange vocal tracks without drums and bass guitars. They are also fast enough to keep up even with Maggies and Eminents. Incidentally, Paul McGowan who is also an Infinity IRS freak swears by REL as the only true subwoofer maker. So, my suggestion to you is to be true to the audiophile path you have chosen and get a good REL to accentuate the Eminents instead of each component playing its own tune (coherency again!). They are not cheap but they are worth every penny.
Best of luck and I hope I helped a bit.
This is my setup now, BTW.

Here is another video of the LFT-8b and F25

@bdp24 Yes, that is a Yorkie.
Regarding the positioning of the speakers. There is a panoramic picture in that link, it shows a sofa with a pillow on it. That is the listening position. As you can see there isnt much space to give the Eminents. They need 3-5 feet behind them and the listening position should have at least that from the back. I guess I should have placed the speakers on the left. Then there would have been plenty of space behind them and also behind me. But when I tried that the sound became muddy, but with excellent depth and imaging. I prefer resolution and details, so I left them almost against the wall.
About the sub placement. I am afraid the speed of the sub or lack of thereof cannot be improved by positioning. Yes, it may become less muddy, but it still will have a heavy woofer that is slow to respond. It will swallow some bass notes. It is all about engineering. A slow sub will create a loud boom. A faster and more resolving sub will create different notes, you will be able to her a pluck of bass guitar or even several guitars just from the sub alone, the attack and decay are clearly heard. Even a better sub with a light driver will create more details, you will hear your midrange (violins, trumpets and voices) with more body, more space, more palpable. It will not be earth shattering, but that is precisely the point.
I m afraid if a sub cant reproduce bass correctly it doesnt matter where you placed it. This video explains how a subwoofer should be used in an audiophile setup.
https://www.youtube.com/watch?v=5YvlxKb1fp4