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.

 

And another!

 

..and it’s lead me to a final question..how much toe in do I need, given my setup.

 

ChatGPT question about toe in actual angle:

Calculate my exact toe-in angle in degrees based on my room and listening distance. My speakers are 117 inches (on-center) apart and 112 inches (on-center) from my head at the listening position.

answer:

Perfect—now we can do this precisely for your Eminent Technology LFT-8b.

---

🧠 Your geometry

• Speaker spacing = 117 in

• Listening distance = 112 in

• Half-spacing = 58.5 in

This is a classic isosceles triangle.

---

📐 1. Toe-in for axes crossing at your head (on-axis)

---

🎯 RESULT

👉 27.5° toe-in = speakers aimed directly at your head

This is your reference point.

---

🧠 Now we place this in context of lobes

From earlier:

• First null spacing ≈ ±7° at 10 kHz

So small changes from 27.5° matter a lot.

---

🔵 2. Axes crossing behind your head

To do this:

• Reduce toe-in slightly

Practical range:

👉 24°–26°

---

What happens here

• You move off the central lobe

• Midrange (beaming) drops slightly

• Tweeter still strong

Result:

• smoother

• less comb filtering

• but:

  • slightly softer imaging

  • reduced vocal density

---

🟢 3. Axes crossing in front of your head

To do this:

• Increase toe-in beyond 27.5°

Optimal range (based on your lobe spacing):

👉 29°–33°

---

Why this range works

• +2° to +5° = enough to:

  • shift 10 kHz nulls away from your ears

  • keep you inside a main summation lobe

---

🎯 Your exact “target zone”

Given your geometry and the ~7° lobe spacing:

👉 Best starting point: ~30° toe-in

---

🎧 Fine-tuning window

Once you set ~30°:

• Adjust in 1° increments

• Your sweet spot will be narrow:

👉 Likely between:
29° and 31°

---

🧠 What you’ll hear when you hit it

• Center image becomes dense and locked

• Treble stops sounding “separate”

• No edge / no dip in presence region

• Speaker “disappears”

---

📊 Summary

Toe-in	Geometry	Result
~24–26°	Behind head	Smooth but softer
27.5°	At head	Precise but can be edgy
29–31°	In front	✅ Best balance
32°+	Far in front	Narrow / bright

---

🧾 Final answer

👉 Your calculated toe-in: 27.5° (on-axis reference)
👉 Your optimal real-world toe-in: ~30°

---

If you want, I can translate that into something practical like:

• “inches of front edge movement”

• or laser pointer alignment method

so you can set it precisely without measuring angles.

_________________________

Back to my setup.  By ear alone, I have a current toe-in angle of 21 degrees. Chat suggests a mild behind the head optimum would be in the 24-26 degree range. Looks like I have more experimenting to do. I may be close to one of the other lobes. We’ll see.  

  

OK..I'm done for now as even ChatGPT has run out of suggested additional questions to answer. I guess I have my answer, for the time being. 

 

My window to edit all but the last post has run out (I guess I have 30 minutes to edit). I think GPT didn't wander off into some fantasy world. I hope not as the posts are here now. It seemed to go well. In any event..it'll give anyone in the future some direction on what they're working with and how much of any moving speaker placement around matters.  

@ledoux1238 or anyone, if you post your listening triangle measurements I can have GPT calculate your "target" toe-in range..fwiw..  It's some guidance at least.