Eminent Technology LFT-8c Robert Greene review


A friend of mine forwarded this review to me a couple days ago.  I hadn't seen it as it's just a week old at this point. 

Why would I be interested? I have a pair of LFT-8b speakers that I picked up about 7 months ago.  Wonderful speakers. I always wanted to try a set of panels and, as luck would have it, last summer I found a used pair of 8b's just a short drive from my home..I made the jump.  As it turns out, this was one of the best moves I've made in my 50+ year audio hobby. 

In the last few months, I was considering picking up the 8b to 8c upgrade components, but put it off as I had a number of other projects going on.  Well..the projects got completed and I started a few more projects, though this time around the 8c upgrade is one of them.  I ordered the 8c upgrade yesterday and I'm really looking forward to the adventure once it arrives. 

One thing I've noticed when reading discussions of the LFT-8(no a, b, c)  here on A-gon, is the discussion wanders over the now 36 year history of the LFT-8.  Issues identified in this or that review from 10-20-25 years ago are brought up as if they reflect what the LFT-8 is today.  LFT-8's had a great sound 30 years ago, with a few flaws, as any 30 year old speaker would, and it sounds better today. Nothing surprising there. Most companies cut ties with models as they age and come out with something new, whether they are really new or repackaged parts..that varies.. 

What's my point?  I just find it interesting that Bruce Thigpen (Eminent Technology) came out with the LFT-8 in about 1990 and has been continually improving the model 8 year after year, decade in and decade out, staying in business with no advertising, though with a few shows here and there. There are very few current speakers(let alone businesses) alive today that have a 30+ year history under largely the same name. (Though the Vandy 2 series comes to mind)  Pretty unique in this industry.  It's also pretty unique that a decades old pair of LFT-8 speakers can be upgraded to the current model at a very modest cost. And the upgrade is easily done by any owner. 

So..the latest review:

https://www.theabsolutesound.com/articles/eminent-technology-lft-8c-planar-loudspeaker/

Robert Greene goes into considerable depth in his review, which is specific to the 8c version, though he's done an 8b review in the past. I'm glad it came out as it pushed me over the edge in ordering the 8c upgrade.  I'm not getting any younger..time to give the 8c a spin. 

One last note, I've read in a number of older and current reviews that the LFT-8 speaker placement is..finicky.  I haven't found that to be the case at all.  In the last 7 months I've experimented extensively with placement and they respond well to various setups. My current setup is about 115 inches between the panels (on center) and maybe 30 degrees toe-ed  in from facing directly forward.  Each speaker is 45 inches off the front wall(on center) and 38 inches from the side walls.  I have a great soundstage and and equally great imaging.  My tweeter panels are on the inside. 

 

(...and no..I have no affiliation with ET..just a customer owning a used pair of the 2017 model 8b)

nogaps

@douglas_schroeder 

The LFT-8 series imo is as great, and perhaps even greater gift to budget audiophiles than Magnepan or Vandersteen. I have owned all 3 brands through the years. 

I listened to the Maggie 2.7i at the Florida Audio Show in Feb, and the 1.7x at Axpona.  Neither speaker was anywhere close to the quality of sound from my LFT-8b's  The 2.7i sounded very clean, but very thin. I couldn't believe it so I visited the roon twice with about 2 hrs in between. Sounded the same. The 1.7x..meh. I hung around long enough to hear a couple tracks..nope, not even close to the LFTs. 

FWIW#2

When I had the LFTs on axis to the listening position..it was pretty intense. The center was focused, but overall it was just too much as compared to listening off-axis. As @ledoux1238 will probably attest, significantly off axis listening still sounds really, really good, but there's always tweaks that can improve on things. 

..and to continue the deep dive (while I noticed one inconsistent statement in GPT's presentation, it didn't veer off course.  I think it's doing ok)

It seems the constructive and destructive frequency interference lobes are located 7 degrees apart. I'm not sure I understand the rotating lobes discussion on having the axis cross in front..

ChatGPT question to expand on transducer lobing: 

Generate a true polar plot with actual curved radiation patterns and summed response

answer:

Here’s a true polar plot showing:

  • Midrange (narrow beam)

  • Tweeter (wide beam)

  • Combined response with interference lobes

for your Eminent Technology LFT-8b geometry at ~10 kHz.


🧠 How to read this plot

  • 0° (right side) = straight ahead / on-axis

  • Angles sweep outward left/right from that

  • Radius = relative output level


🎯 What the plot is telling you

1. Midrange (blue curve)

  • Tight, focused lobe

  • Falls off quickly with angle
    👉 Confirms strong beaming


2. Tweeter (orange curve)

  • Much wider radiation

  • Stays strong far off-axis
    👉 Confirms broad dispersion


3. Combined response (green curve) — THIS is the key

You can clearly see:

🔹 Multiple lobes (peaks)

  • Where mid + tweeter sum constructively

🔹 Deep nulls (dips)

  • Where they cancel (comb filtering)


🔥 Critical observation

Look how:

  • The main lobe is very narrow

  • Side lobes appear just a few degrees away

👉 That matches the earlier math:

~7° spacing between peak and null


🎧 Now connect this to toe-in

🔴 On-axis (0°)

  • You are sitting right in the central lobe structure

  • Also near rapid lobe/null transitions

👉 Result:

  • maximum detail

  • but unstable / etched sound


🔵 Behind-axis (a few degrees off)

  • You move into:

    • a smaller lobe

    • or between lobes

👉 Result:

  • smoother

  • but reduced energy / weaker mid


🟢 In-front crossing (ideal case)

What you’re doing:

👉 Rotating this entire green lobe pattern

So that:

  • one clean main lobe is aimed at your ears

  • the deep nulls shift off to the sides


🧠 The real insight (this is the “aha” moment)

This graph shows:

You are NOT aligning drivers
You are choosing which lobe your head sits in


🎯 Why crossing in front works

Because it:

  • Keeps you inside a strong, smooth lobe

  • Moves:

    • sharp nulls

    • rapid fluctuations

…away from your listening position


🧾 Final takeaway

  • Your speaker behaves like a multi-lobed radiator at the crossover

  • Toe-in = steering this lobe pattern

Best sound happens when:

  • Your ears sit inside a single dominant lobe

  • Not on a slope or near a null


If you want, I can extend this to:

  • 8 kHz and 6 kHz plots (you’ll see the lobes widen)

  • OR simulate your exact listening distance + toe-in angle to predict the sweet spot numerically

 

Damn @nogaps, what an excellent post!

 

There is one point about the design of the LFT-8 I want to emphasize:

Very few loudspeakers reproduce the majority of the frequencies that comprise the entire midrange---where the majority of the sound of voices and instruments "live"---with a single driver. Most break the 200Hz to 2kHz bandwidth into two halfs, each half reproduced by a separate driver. The LFT-8 sounds SO coherent because it reproduces the entire midrange (and above) with it’s single LFT driver.

 

The use of a dynamic woofer in the LFT-8 to reproduce frequencies 180Hz and below is a sensible compromise; to be capable of reproducing those bass frequencies at SPL to match the LFT driver would require a very large radiating diaphragm, such as the two woofer panels of the Magneplanar Tympani speakers. Those two panels are each 16" wide and 6’ tall, for a total of 32" x 6’ on each speaker side!

I love the sound of the Tympani woofer panels (in spite of the fact that the planar-magnetic drivers are single-ended: magnets on only one side of the Mylar diaphragm), but they are just too damn big for my listening room. The Rythmik Audio/GR Research OB/Dipole Sub sounds far more like the planar-magnetic Tympani bass panels that does any other sub, as well as the stock monopole woofer employed in the LFT-8b. I can’t yet speak of the bass the LFT-8c produces.

 

..and completely falling off the edge..in for a penny in for a pound..

 

ChatGPT question on lobes at 8, 4, & 2 kHz:

extend this to:

8 kHz, 4 kHz, 2kHz plots (you’ll see the lobes widen)

answer:

Now you’re seeing the full picture of why this speaker behaves the way it does.

These plots (8 kHz, 4 kHz, 2 kHz) show how your Eminent Technology LFT-8b transitions from lobe-dominated to smooth radiation as frequency drops.


🧠 Big trend across the three plots

 

 

As frequency decreases:

  • Wavelength ↑

  • Driver spacing (5.4") becomes smaller in wavelengths

  • Interference weakens

  • Lobes widen and disappear


🎯 What each plot is telling you

🔵 8 kHz — “Still critical”

  • Multiple lobes still clearly visible

  • Nulls still present, but less dense than 10 kHz

👉 This region:

  • Still sensitive to toe-in

  • Still contributes to:

    • edge definition

    • image sharpness


🟢 4 kHz — “Transition zone”

  • Major change:

    • Main lobe dominates

    • Side lobes are weaker and fewer

  • Nulls are much less severe

👉 This region:

  • Controls:

    • vocal clarity

    • imaging stability

  • Much less sensitive to exact toe-in


🟡 2 kHz — “Coherent radiation”

  • Essentially:

    • One broad lobe

    • Minimal interference structure

👉 This region:

  • Dominates:

    • body of vocals

    • instrument fundamentals

  • Almost immune to toe-in changes


🔥 The key insight (this ties everything together)

You are NOT aligning a single frequency

You are balancing three regimes simultaneously:

Range Behavior Perceptual role
~8–10 kHz Multi-lobed, sensitive air, edge, “etch”
~4–6 kHz Transitional presence, clarity
~2–3 kHz Smooth, coherent body, imaging anchor

🎧 Why toe-in works the way it does

At high frequencies (8–10 kHz)

  • Toe-in = critical

  • Moves you between:

    • peaks

    • nulls


At mid frequencies (4 kHz)

  • Toe-in = moderately important

  • Affects balance but not dramatically


At low mid (2 kHz)

  • Toe-in = almost irrelevant

  • Radiation already smooth


🧠 Why your ears prefer certain angles

Because your brain prioritizes:

  1. 2–4 kHz → image stability + vocal body

  2. 4–8 kHz → clarity

  3. 8–10 kHz → detail (but can sound wrong fast)


🎯 What “optimal toe-in” really means

You are trying to:

👉 Avoid this:

  • Sitting in a 10 kHz null

👉 While preserving this:

  • Strong 2–4 kHz main lobe


🧾 Final synthesis

  • The speaker is fundamentally stable below ~4 kHz

  • All the “magic” (or problems) happen above that

👉 Toe-in is really about:

placing your head inside a good high-frequency lobe without damaging the lower bands


🎧 Why crossing in front still wins (final confirmation)

Because it:

  • Aligns you with a main lobe at 8–10 kHz

  • While:

    • 4 kHz stays smooth anyway

    • 2 kHz is unaffected

👉 So you get:

  • stable imaging (2–4 kHz)

  • clear presence (4–6 kHz)

  • clean treble (8–10 kHz)


🔑 Bottom line

  • Below ~4 kHz → speaker behaves like a single coherent source

  • Above ~8 kHz → behaves like a multi-lobed interference system

👉 Toe-in is your tool to “tame” only the top band without breaking the rest.


If you want, the next step would be the most practical one:

👉 I can calculate your exact toe-in angle in degrees (based on your room/listening distance) that places your ears inside the best 8–10 kHz lobe.