Pairing Planar Speakers With A Subwoofer (Eminent Technology)

What do you think of pairing the Eminent Technology LFT 8-B planars with a pair of Rythmik F25 subwoofers?

Please check out my room on my system page. I am attempting to emulate a set of Infinity IRS Betas.

System page:

Eminent Technology LFT 8-B:

Rythmik F25 subwoofer:

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Hi Mitch I took a look at your links, I have not heard the Rythmik, but they look superb, key feature servo controlled, like the Betas. Still using the same room shown in the link? Wow what a killer room! I run a large pair of ribbon hybrids, with twin subs. and we are very content. I have always liked Infinity, my first serious system when I was young, was a pair of Infinty RS IIb speakers. At any rate, should be a great match! 
Not as popular as the brands you mentioned. But I used the TBI Sound Magellan Subwoofer with my ET's. Fastest most musical sub I have heard. Based in Georgia, give them a call. Nice people.

Mitch, the F25 is indeed an excellent sub, and will work quite well with the ET LFT-8b. I have a pair of F15HP’s (DIY version---I made my own 4cu.ft. enclosures), which have a single 15 woofer to the F25’s dual 15’s. Same sq, but the F25 has greater maximum spl. Both the F15 and F25 are being used successfully with magnetic-planar (mostly Magneplanars), ESL, and ribbon loudspeakers.

For reference, I am a former owner of Infinity RS-1b’s, and I consider the ET LFT-8b a superior loudspeaker. However, the LFT-8’s single 8" woofer is no match for the RS-1b’s servo-feedback woofer column, with it’s 6-8" woofers. Any of the Rythmik servo-feedback subs will be a great partner for the LFT-8 (used in place of the ET’s woofer), creating a very full-range, high-output hybrid. But for the ultimate version of such a design, there is an even better sub for use with dipole speakers, one also available from Rythmik’s Brian Ding, in a collaborative effort with Danny Richie of GR Research: their Servo-Feedback OB/Dipole Subwoofer, the only such design in the world! You can read about it on the GR Research AudioCircle Forum---there is too much to it for me to post here.

$1500 for a pair of the sub kits (a pair of 12" woofers with the Rythmik servo-feedback plate amp per side), another $500 for a pair of the H-frames they are installed in. $2500 for the ET LFT-8b’s, $2000 for the subs (plus the cost to finish the H-frames)---$4500 for performance far exceeding what you expect at that price point imo. The ultimate magnetic-planar/dynamic sub hybrid! Imagine---a dipole planar speaker with a dipole/OB sub---a perfect pairing!! I can say all this not just hypothetically and from theory, but from practice---this hybrid is my creation! As far as I know, I am the only ET LFT-8b/OB-Dipole Sub owner in the world. But the OB/Dipole Sub s being used with lots of other high-performance speakers, mostly ribbons. Ric Schultz of EVS has designed and is selling such a design, using the Rythmik/GR Research OB/Dipole Sub.

Hi I have Magnepan 1.7s... originally I had a Rel T7 sub paired. Honestly, IMO it was just ok and I was wrestling with a love/hate relationship with the Maggies. Then my Rel blew a Diode.. so while it was down I quick picked up PSB subwoofer cheap. Crazy as this may seem.. the PSB pulled everything together. My sound never sounded better.. for all genres of music. I fixed the Rel, sold the PSB and immediately regretted it... bought a new PSB and have been happy ever since & it keeps sounding better and better as it broke in. It matches so good with my Maggie’s that I’ve actually considered starting a thread on it... I think other Maggie owners may be interested. Just another thing to consider.
good luck!
I use a pair of 12" Rythmik subs with little Maggies and they integrate seamlessly (to my ear, anyhow).  I use Audyssey to effect the xover and add room correction

The hybrid LF8 presents a different (lesser)  challenge given the cone bass driver, so I don't see why it would be tough to pair with a sub.
I don't know much about the Eminent speakers but they have always intrigued me. I currently have two sets of ESLs. Quad ESL 57s and Music Reference ESLs. I shied away from subwoofers because I thought they made things a bit too complex and I never could get used to the idea of bass being driven by plate amps. So I listened to my ESL 57s with my OTLs and enjoyed what bass they could muster, which quite frankly was more than I expected. Then Roger Modjeski introduced me to his Airspring woofer system that he uses with his ESLs, which by design only go down to 100 Hz, so they require something to provide the bottom end. He fixed up a Class A/B solid state amp with a low pass filter for me and I made two of the woofer boxes myself. Once I put that in my system there was no going back.

Today I use a Beveridge RM-3 as the crossover with 100 Hz boards, my OTLs on top driving the ESL 57s or the MR ESLs, and a Luxman M-02 driving not 2 but 4 woofer boxes spread asymmetrically around the room. This has done more to improve the sound in my room more than anything else I have ever tried. So for me biamping was the ticket and I imagine you can attain the same effect with good subwoofers. In fact I'd recommend checking out the Audiokinesis Swarm which is a nice little system that would play well with the LF8s.
What happened to the DD-18 on your list? 

If you still have it I'd slave it from a 10" or 12" DD Plus for a sort of modular 1812. I had one brief experience a few years ago setting up a pair of DD-10 Plus with a receiver equipped with Audyssey (I don't recall which level or the setup details). In that room the Velodyne Manual Room Optimization procedure did a noticeably better job of the basic integration than Audyssey not to mention the two custom movie presets.

I'm sure there have been Audyssey upgrades since then. I found it to be so useful with the rest of the system in this particular room I wouldn't dare dismiss its capabilities. DD-18 is for home theater only.

I want an identical stereo pair of subs for music only.
I tried my two 12" Plus using separate left and right signals and located near the speakers which seemed OK but left many room nodes. Summing the signal at the same speaker location increased solidity or possibly just loaded the room better but the nodes were still present.

Finally positioning the subs in two irregular locations using a summed signal really locked the room and eliminated all but a few extreme corner nodes.Then again every room is different when it comes to the low end.

The Plus can be simultaneously connected to both a stereo and HT systems. 

 Good luck with it.
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.

Hey @grigorianvlad, is that a Yorkie? Great little dogs!

As an owner of Maggies, ET LFT-8b’s, and Quad ESL’s, I have to ask you: is where your panels are located in the pics where you listened to them at? The common wisdom is that planars need to be at an absolute minimum 3’ from the wall behind them, but I consider 5’ a better number.

And as an owner of a number of subs (GR Research/Rythmik, Rythmik, HSU, KEF B139’s in transmissionline enclosures, former Infinity RS-1b owner), I have to ask: did you try the F25 in different locations in your room? Corners are the absolute worst place for subs, if sound quality rather than quantity is the priority.

Damn that F25 is big!

@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.

The perceived "speed" of a sub is greatly influenced by the room, where in the room the sub(s) is(are) positioned, not merely the mass of the sub’s driver. "I am afraid the speed of the sub or lack thereof cannot be improved by positioning". No, but it certainly can be made worse by poor positioning! By the way, do you know the mass of the Rythmik and REL woofers? How about that of the GR Research 12" paper-coned woofer? How about the gauss figure of those woofers motors (magnets), without which the cone's mass figure is irrelevant?

Regarding the distance a planar is from the wall behind it, that distance effects not only depth and imaging, but also frequency response via comb filtering. The back wave of the planar reflects off the rear wall, meets the front wave, causing frequency-related cancellation and reinforcement.

@bdp24  Good to know, thank you. 
I wonder if @mitch4t ended up buying both the Eminents and the Rythmiks?  What are his thoughts?
The Eminents are notoriously inefficient. Before them I had Polk LSiM705's with sensitivity of 88dB/W/m. Room calibration set them at -7dB (from -12dB to +12dB). The Eminents are rated 84dB/W/ml. So, naturally I assumed that auto calibration will set them at -3dB to create the same sound level, to compensate for low sensitivity. Guess what. It set it at +7dB, a whole 14dB louder! You need a lot of juice to power them, the 75W minimum power rating isn't realistic. I had a 600W@8ohm power amp and it barely did the job. They also took around 6-7 months to break in.
Yup, they like juice. The Maggies are far hungrier, though (I’ve owned four pair, including the Tympani-IVa’s I now have). The ET"s have a nominal impedance of 8 ohms to the Maggies 4 ohms. The LFT panels on their own are an 11 ohm load, so a moderately powered tube amp works great with them. Then a solid state amp can be used for the woofers.
@bdp24 What is amazing about the Eminents is that their midrange driver handles the range of 180Hz to 10kHz without a crossover. The Absolute Sound review is right on target. Such open and transparent speakers. But as ugly as genital warts. Their WAF is negative one million.
They're not too terribly bad with the grills in place, but without them they're about as ugly as speakers get! I'm thinking about taking off the stock cloth, and putting on some real sheer stuff that's acoustically transparent. 
I have paired them with  a pair of Vandersteen 2Wq subwoofers. Superb, seamless and I consider it a 3-in-1 upgrade as the unique feedforward design of the 2Wq's frees up more juice for these power hungry speakers, which benefit also by only having to play from 80hz upward- less juice required. My amps don't work as hard.
My brother walked into the house and commented, without entering my listening room, how effortless my hi-fi sounded.
Getting a subwoofer, and succeeding, requires room tuing AND advanced EQ. JL Audio subs have the latter built in for a fortune.

I think this could be a great sub, but it has no good EQ options. You'll have to figure that out separately. The 1 band EQ option is not enough.


Erik, that’s the one element of the Rythmik subs that seems questionable to me. 1-band of parametric room EQ? Why bother! I suppose it’s better than nothing, but what room has only one bass mode? With the introduction of the new DSPeaker Anti-Mode X4, the 2.0 Dual Core is now available for $500, and can be used with a pair of stereo subs or speakers. Money very well spent.
@bdp24 - Exactly! There's always at least 2 1/2. :)

It's really not worth an add-on price. It's not going to do something for you that a Hsu won't do for free.

$500 sounds pretty good. You don't have to buy the measuring microphone, etc.


The 1-band ParaEQ is not the selling point of Rythmik subs, or what you’re paying for. Brian Ding’s patented Direct Servo-Feedback design is quite an engineering feat, solving problems other sub designers don’t even acknowledge, let alone address, and his woofers excellent in design and build. I don’t imagine it costs Brian much to throw the EQ in, but I don’t see the point. My pair of DIY F15HP Rythmiks (in 4cu.ft. sealed enclosures) replaced a pair of Hsu’s, and though Peter’s subs are fine ones, they are no Rythmiks!
I know I am a fanboy
but the new Vandersteen sub has 11 bands of analog EQ
target $2,500 each
not cheap
but why not listen ??????
@mitch4t , your room is stunning but dsp would, I imagine, be a must with all that glass and no room treatment. I find JRiver's onboard options very useful- even without any room correction software (just playing Alan Parsons' test tones and sweeps over and over and adjusting certain frequencies with varying Q worked well to tame room modes), but that only applies to digital playback I guess.
I love those speakers.  Have had them in my home a few different times over the last MANY MANY years, lol.  The brand new Vandersteen Sub 3' system would work great. I know they are very very fast subs (I own Quatro's and know how fast they are).  Their amp mimics the amp in the main system, which is one of, if not the only one that does this.  It's a simple, but great idea.  It also includes an EQ on each sub so you can dial in the bass so you can easily smooth it out in any room.  

I have a very difficult room and it works GREAT.  As we all know, it's hard to get fast sub bass that will integrate well with the ET's.  You have some good options, but make sure to set them up properly or you will never be happy.  The ET's have a special magic and you don't want to ruin them with subterranean  bass that isn't fast enough to keep up with the panels and won't integrate with the ET's own bass driver.  That's one reason I love the amp that mimics your's.  JMHO
wow.....Ok, this just in.  Not a fanboy of listening at a show for MANY reason's that are obvious.  IF something sounds GREAT at a show it still may not sound great at home.  Think of TV's in teh store that are all set to the brightest settings to compensate for the harsh lights AND to stand out from the others.  I personally pay the extra few hundy to get them fully calibrated to look their BEST in MY rooms!  

I will use a review or feedback from friends who's ears I know well to put something on my must audition list.  Feedback from a few friends about teh Sub 3's in convo's yesterday is that the Sub 3 is a MUST audition.

Even for those of us with full range systems already, the Sub 3 will free up even more of the headroom space on an amp.  It will smooth out even more your in room bass response (the EQ is kind of magic like this and unlike a digital EQ, you don't hear the analog one that Richard has designed.  As with all Vandersteen products, he's all about getting more than your money's worth and he hit this one out of the park according to folks I know who listened.  

For me, it's on my MUST audition as soon as I'm able to.  I have a feeling that these will do more for my system than spending another 5k on the speakers themselves. I'll hear for myself once that times comes, but it's on the radar as throwing down the gauntlet in the 5k and under category from the sounds of it.  Happy Listening.
Ctsooner...I went to the Vandersteen web page and did not see the model you speak of.  
Please provide a link to this sub.
no link yet Mitch.  They are brand new and only being shown at the shows right now.  Dealers will get theirs in a few weeks I believe.  I know about the EQ, but am not totally sure of what else they will have.  I believe the cabinets will look similar to their current model that was phased out over the last couple of months.  Do you have a Vandersteen dealer near you?  If so, get in touch and they will surly know.

I have JansZen hybrid Valentina ESLs mated to twin Rythmik 12G subs.  I think the key for my setup was a combination of settings. First, crossing over the subs just below the 30Hz level with the steepest filter slope, the bottom range of flat response for the integrated woofers on the JansZens.  

Second, setting the bass extension controls with maximum damping allowed to subs to play in a similar manner as the speaker woofers. Gettng the volume control on the subs so that the contribution felt simply like extension and not additional bass was also key. 

I ran the JanZens without subs for quite a few years before getting the subs but I wanted more impact and bass foundation.  I was afraid they would make things too thick sounding.  They don't when dialed in right.

I would think the new Vandersteen sub 3's would be a GREAT choice to mate up to them with their bass EQ.  Plus they would keep up with the speed of that speaker, which isn't easy for subs to do.
What about simplifying and getting a pair of Bob Carver Amazing Line Source speakers with his complementary Sub Rosa subwoofer and amp?
Bob Carver Amazing Line Source and Sub Rosa sub and amp

planars & cone subs don't play well together

but many do it anyway
Many dynamic powered subwoofers are very much up to the task if they have the right performance parameters *and* features. I have a pair of self-powered compact (9" cube) Mirage MM8 subwoofers that blend naturally with my Magnepan 1.7s:

  • The subs are sealed enclosures with passive radiators
  • They have light, rigid 8" aluminum diaphragms with linear high-excursion surrounds
  • They have internal 1200-watt power amplifiers (which control diaphragm motion as quickly as my 200 wpc amp controls the panels)
Controls (essential to getting a good blend) include:
  • Variable crossover from 50-200 Hz
  • Variable phase control from 0 to 360 deg.
  • Variable volume control
The Magnepans roll off at about 45 Hz so I set the subs' crossovers to 50 Hz.
I place the subs for optimum bass extension and clarity. In my case the active drivers face the wall behind the main speakers, which pressure loads the bass waves and uses the back wall to reinforce volume and extension.
I adjust the subs' volume controls to match the perceived volume of the mains.

The thing that gets the whole arrangement to "pop into focus" is to set the phase controls so they sync up with the mains:
  • I use a mono recording of The Beatles' "With a Little Help From My Friends." In that recording, Paul McCartney's bass line is very melodic and crosses back and forth above and below the 50 Hz crossover point.
  • I set phase one sub at a time, moving the phase knob until one channel syncs up and is focused.
  • Then I do the same with the other channel.

I have used this setup of dynamic self-powered subs and a pair of Maggie panels for almost 5 years straight. The whole system sounds right in every aspect--timbre, timing, undetectable transitions, focused stereo image and soundstage, you name it.