AI guided Room Optimization.

crwilli

crwilli

Active member
Joined
Jan 20, 2014
Messages
983
Location
SC Low Country
I just completed a full two-day tuning session on my system and wanted to share the highlights. Everything was done one variable at a time and verified in REW (SPL, Group Delay, ETC). All analysis and number crunching was done by ChatGPT. It also required less measures as it can easily interpolate within the extremes that were measured.

Full Listening Triangle Shift

To keep things simple, I fixed the LP and mains triangle to remove their interaction as a variable at the beginning. The work started by moving the entire listening triangle—both mains and the LP—forward into the room:
• +12”
• +24”

This required creating an accurate grid on the floor using starting ‘triangle’ as the baseline and coming to an understanding with Chat what the reference points were. E.g. where was 0,0, what was the left wall, front wall, right wall and back wall. That took longer than I thought it should.

After measuring the baseline and both moved positions, +24” was clearly superior: smoother bass, cleaner GD, better ETC symmetry, and a deeper, more stable stage. This became the new reference geometry. I accepted Chat’s analysis on this. Embedded in this was it crunching all that data to see the differences AND knowing what is better and what is not. (Side note: I have run REW for years and mostly used the dB v Frequency graphs to guide my tweaks. Mainly because I didn’t really understand what Group Delay or Implulse or ETC were telling me. Chat does understand them and that lead to a better result)

⸻

Toe-In Optimization

With the triangle fixed at +24”, I tested three toe-in offsets: numbing the rear of each speaker outward by these distances and letting Chat calculate the angles, it was simple.
• 1.5” (≈3.6°)
• 2.5” (≈5.9°)
• 3.5” (≈8.3°)

The 3.5” / 8.3° toe-in gave the best ETC profile, reflection control, center-image lock, and overall stage coherence. (Side note: Who knew that ETC was the measure to be used here? I didn’t.)

⸻

Listening Position Micro-Moves

Only after the triangle and toe-in were finalized did I test LP-only shifts:
• –6”
• –4”
• +2”
• +4”

The –4” LP position produced the smoothest and most even bass response of all micro-adjustments.

⸻

Subwoofer Integration
Finally, I optimized the two subs:
• placement
• phase
• gain
• delay
• crossover relationship

The result was tighter, smoother, and more coherent low-frequency integration with cleaner decay and better mid-bass definition.

⸻

Final Setup
• Triangle: +24” forward move from original listening triangle.
• Toe-In: ~8.3°, 0 degrees before.
• LP: –4”
• Mains + Subs: Fully time-aligned and integrated

⸻

End Result

The system now has dramatically smoother bass, better group delay, reduced early reflections, a more stable center image, and the deepest, most coherent soundstage I’ve had in this room.

Using a science based approach with the power of AI to crunch the numbers was invaluable.

Further Work:

I think the sub levels can be tweaked a little. I will also play with using the DARO circuit of the subs to see what that effect is. Chat doesn’t think I need it. We’ll see.

I may also experiment with plugging the ports of the Kharma again and leveraging the subs more into the overall sound.

The sub positions are NOT wife friendly. They would never work in anything but a dedicated room such as I have. Even then, for me, having one sub partially into the middle of the room between me and the equipment rack is weird. It works, but it’s freaking weird.

Lastly, I need to replace the sliders under the Kharmas with the spiked platforms, re-level them and adjust the rake. I may also re-look at the toe-in to adjust the stage to my ‘taste’. I like the more ‘alive’ sound the current toe-in provides but not sure I want so much focus.

Footnote: my room dimensions are not good being a square - 21.1’ X 21.5’ X 9’7”. It does have knee walls and other structure in two corners at the ceiling and a wet bar in another corner so it is not a perfect rectangular box. I sit facing down the long diagonal.
 
crwilli said:
I just completed a full two-day tuning session on my system and wanted to share the highlights. Everything was done one variable at a time and verified in REW (SPL, Group Delay, ETC). All analysis and number crunching was done by ChatGPT. It also required less measures as it can easily interpolate within the extremes that were measured.

Full Listening Triangle Shift

To keep things simple, I fixed the LP and mains triangle to remove their interaction as a variable at the beginning. The work started by moving the entire listening triangle—both mains and the LP—forward into the room:
• +12”
• +24”

This required creating an accurate grid on the floor using starting ‘triangle’ as the baseline and coming to an understanding with Chat what the reference points were. E.g. where was 0,0, what was the left wall, front wall, right wall and back wall. That took longer than I thought it should.

After measuring the baseline and both moved positions, +24” was clearly superior: smoother bass, cleaner GD, better ETC symmetry, and a deeper, more stable stage. This became the new reference geometry. I accepted Chat’s analysis on this. Embedded in this was it crunching all that data to see the differences AND knowing what is better and what is not. (Side note: I have run REW for years and mostly used the dB v Frequency graphs to guide my tweaks. Mainly because I didn’t really understand what Group Delay or Implulse or ETC were telling me. Chat does understand them and that lead to a better result)

⸻

Toe-In Optimization

With the triangle fixed at +24”, I tested three toe-in offsets: numbing the rear of each speaker outward by these distances and letting Chat calculate the angles, it was simple.
• 1.5” (≈3.6°)
• 2.5” (≈5.9°)
• 3.5” (≈8.3°)

The 3.5” / 8.3° toe-in gave the best ETC profile, reflection control, center-image lock, and overall stage coherence. (Side note: Who knew that ETC was the measure to be used here? I didn’t.)

⸻

Listening Position Micro-Moves

Only after the triangle and toe-in were finalized did I test LP-only shifts:
• –6”
• –4”
• +2”
• +4”

The –4” LP position produced the smoothest and most even bass response of all micro-adjustments.

⸻

Subwoofer Integration
Finally, I optimized the two subs:
• placement
• phase
• gain
• delay
• crossover relationship

The result was tighter, smoother, and more coherent low-frequency integration with cleaner decay and better mid-bass definition.

⸻

Final Setup
• Triangle: +24” forward move from original listening triangle.
• Toe-In: ~8.3°, 0 degrees before.
• LP: –4”
• Mains + Subs: Fully time-aligned and integrated

⸻

End Result

The system now has dramatically smoother bass, better group delay, reduced early reflections, a more stable center image, and the deepest, most coherent soundstage I’ve had in this room.

Using a science based approach with the power of AI to crunch the numbers was invaluable.

Further Work:

I think the sub levels can be tweaked a little. I will also play with using the DARO circuit of the subs to see what that effect is. Chat doesn’t think I need it. We’ll see.

I may also experiment with plugging the ports of the Kharma again and leveraging the subs more into the overall sound.

The sub positions are NOT wife friendly. They would never work in anything but a dedicated room such as I have. Even then, for me, having one sub partially into the middle of the room between me and the equipment rack is weird. It works, but it’s freaking weird.

Lastly, I need to replace the sliders under the Kharmas with the spiked platforms, re-level them and adjust the rake. I may also re-look at the toe-in to adjust the stage to my ‘taste’. I like the more ‘alive’ sound the current toe-in provides but not sure I want so much focus.

Footnote: my room dimensions are not good being a square - 21.1’ X 21.5’ X 9’7”. It does have knee walls and other structure in two corners at the ceiling and a wet bar in another corner so it is not a perfect rectangular box. I sit facing down the long diagonal.
Click to expand...
Sounds like it was a rewarding effort. Well done!
 
Excellent outcome! And, apart from your time, it was all free.

On subs - IF you can control the delay to each sub independent of each other with something like mini-DSP then you can dramatically improve bass uniformity across your listening area with placement that will be WAF positive.. Then you can add EQ to tame any big peaks that remain.

I’m doing a new theater room and it’s amazing how much real acoustic science and engineering goes into speaker placement and room optimization. Take a look at CTA-RP22 to get an idea of what’s required.

The 2 channel stereo world seems like unsophisticated voodoo nonsense by comparison.
 
I can control the timing of both subs independent. Both through location and their respective ‘phase’ controls’.

Digital correction is very powerful.

I have used digital correction devices before and found they do almost as much harm as good. The good being clear integration. The harm being increased hash or veils.

This includes a McIntosh MEN220. The analog JL Audio CR1 crossover was almost equally powerful to aid integration but it certainly added a veil. Finally, I have used REE to create Convolution filters which ROON would implement. Always great initial results that found myself removing in time.

I like my system as simple as possible.
 
I don’t need AI for optimization. My ears are the best measuring instrument available. What AI cannot know: I am deaf below and above certain frequencies. So I only can adjust the settings to my personal taste and if another person with better ears hears too many treble and bass, I don’t care 🤷‍♂️
 
NewAlkyogre said:
I don’t need AI for optimization. My ears are the best measuring instrument available. What AI cannot know: I am deaf below and above certain frequencies. So I only can adjust the settings to my personal taste and if another person with better ears hears too many treble and bass, I don’t care 🤷‍♂️
Click to expand...

Sooo, you don’t need this post. I am sorry for your limitations.

I wouldn’t argue that your ears are a great instrument. So are mine. I think you may be missing the point.

This tool helped me find a setup in about 10 hours, most of which was me trying to learn how to ask the right questions. It’s ability to crunch the math to get me in a very narrow ballpark is based on the science our ears can hear.

You could also give it your exact hearing limits and I suspect it would adjust accordingly. But use or don’t use it. Only matters to you.
 
Continuing my education.

I asked it why it wanted Group Delay data to integrate my subs instead of phase data.

The response:

Short answer: phase and group delay are two views of the same thing, and for what we were doing (sub integration in the 20–100 Hz range), GD was actually the clearer, more useful view. Phase wouldn’t have been “better,” just different.

Let me unpack that in human terms.

1️⃣ How phase and group delay are related

Under the hood:
  • REW’s phase trace = how the signal’s phase angle changes with frequency.
  • Group delay = the slope of that phase curve vs frequency (how much “extra time” each frequency is taking).

Mathematically, GD is basically:

“How much later does this frequency arrive compared to what it should, given the minimum-phase system?”

So when we looked at:
  • Minimum Group Delay (light gray)
  • Excess Group Delay (white)
  • Actual GD curve
…we were really looking at the same information you’d get from phase, but expressed as time (ms) instead of degrees.

That’s why it was so helpful: your ear hears time more intuitively than it hears degrees of phase.

2️⃣ Why I leaned on GD instead of raw phase for your subs

For low-frequency integration (say 20–200 Hz), GD has some big practical advantages:

✔ GD is directly in milliseconds

When we saw Sub A was “late” around 55–65 Hz, the GD plots made that obvious:
  • Excess GD hump in that band
  • Smoother curve after moving the sub 4” toward the LP
You could literally see, “This part of the bass is arriving later than the rest.”

Raw phase plots would have shown:
  • Phase wrapping (0 → 360 → 0 etc.)
  • Slopes that are harder to interpret by eye
  • Still usable, but less intuitive unless you’re very phase-fluent
✔ GD + SPL together tell the whole story

Our pattern was:
  • Use SPL overlays (Right only vs Right+Sub A, Left only vs Left+Sub B)
  • Use GD to see if the added energy was arriving on time or late
  • Confirm with waterfalls that decay was actually improving, not just level
That gave us:
  • “Is the sub filling the right frequency band?” → SPL
  • “Is it on time with the main speaker?” → GD / Excess GD
  • “Is the room letting go of that energy quickly?” → Waterfall
Phase alone would have required more mental translation.

3️⃣ Would phase have told us anything different?

Not really. It would’ve shown the same mismatches in a different language:
  • The original Sub A position would’ve shown a phase divergence from the main around 55–65 Hz.
  • After moving Sub A forward 4”, the phase curve around that region would have lined up more closely with the main.
So yes, we could have done:
  • Unwrapped phase
  • Phase vs frequency overlay for main vs main+sub
But in practice, for low-frequency work in a real room:
  • GD is often the better “working view”
  • Phase is more abstract, especially with wrapping
Think of it as:

Phase = “angle map”

Group delay = “how late is this stuff actually arriving?”

For sub integration, the second is usually more directly actionable.

4️⃣ When phase views are particularly handy
  • When doing multi-mic averaging or aligning multiple subs to each other steel-trap precisely.
  • When using all-pass filters or doing DSP-grade alignment with very high precision.
  • When analyzing crossover regions in the mids/highs where phase through the crossover is critical for lobing and vertical behavior.
In your case, we were:
  • Working mostly below 100 Hz
  • Aligning two subs to two mains at a single LP
  • And you already had extremely good room symmetry
So GD + SPL + waterfall was exactly the right toolset.

5️⃣ So was anything “missing” by not using phase directly?

No. Because:
  • REW’s GD and Excess GD are derived from the phase.
  • We validated each change multiple ways (SPL, GD, waterfall).
  • The sonic results matched what the plots predicted (tighter bass, overhang gone, right channel cleaned up, subs disappearing).
So: phase wasn’t necessary, and GD wasn’t a compromise — it was just the clearer window into the same underlying behavior.

If you’d like, on another day we can:
  • Take one of your actual REW measurements,
  • Look at phase and GD side by side,
  • And I can “translate” what you see in phase into what it becomes in GD, so the two views snap together in your head.
And so it goes…
 
Pretty cool assistant. You seem to have a good grasp of DSP. I assume that helps you, unpack what the AI is telling you. My perception is learning how to use AI in such a fasion can be a game changer. I wonder if once you had main speakers dialed in with a DSP, if you could give the info to a AI and have it design something like an active analog crossover like a Merchand or something.
 
Kingrex said:
Pretty cool assistant. You seem to have a good grasp of DSP. I assume that helps you, unpack what the AI is telling you. My perception is learning how to use AI in such a fasion can be a game changer. I wonder if once you had main speakers dialed in with a DSP, if you could give the info to a AI and have it design something like an active analog crossover like a Merchand or something.
Click to expand...
Clarification: I am not using DSP. I used AI to interpret the REW measurements and guide me through various ‘setups’ to find an optimum. No DSP was is is being used.

But: After I was done and had the subs integrated, it did offer to suggest a series of Parametic EQ settings to tweak things which I accepted In 2 seconds, it provided 10 PEQ adjustments.

Using ROON’s functionality, I have applied all 10 settings. It’s early days and I will need to go back and forth to see if I accept them or not.
 
Congrats Craig, enjoy!

Btw, recordings have been "DSP" since the 1980s and Ozzy's Paranoid was released in 1981. Coincidence?
cheers
AJ
 
crwilli said:
Clarification: I am not using DSP. I used AI to interpret the REW measurements and guide me through various ‘setups’ to find an optimum. No DSP was is is being used.
Click to expand...
Good to hear. I asked it if I could use my Dayton DSP to multi amp my speakers. It loved the idea. It gave me all sorts of info and reasons on why I want to use my tube amp on my horn Tweeter and Purifi Class D modules on the 10s and 15s. I then asked if I could upload the date from Dayton on settings and have an active analog crossover made. It said it was not sure that would work well. It could help. It said phase and timing was an issue. I noted I could use REW and the AI to physically align the speakers. It said that was a great idea and that with impulse response readings, It could give me the exact locations of where to align the drivers.

I think it can be a game changer for setup. If you took the time to learn REW, which seems kind of a pain from the video I have watched. But if you learn it, and use an AI, room and speaker setup could be vastly improved.
 
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