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DIYSG HTM-12v2 Review

abdo123

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Correct me if I’m wrong, but isn’t this also the kind of testing that’s a little easier for you and I to do with just a mic and some space, and not a whole NFS system?

There is no point in me testing a product while I own it (at least not that sort of testing that is not reproducible / relatable to other people and their conditions).

If I bought the product i’m either satisfied or not, I wouldn’t be interested in doing distortion measurements unless i hear something wrong.
 

johnp98

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Thanks so much for all the work it took to measure these!

I am wondering logistics about EQing these and have three ideas:
We know from the Klippel measurements that there is very impressive directivity and thus the speaker is prime for EQing.

Idea #1: Hopefully once the raw data (for the direct on axis response) is posted it can be imported into REW and used to generate a very accurate EQ for the mid/high end and then use in room response below the Schroeder frequency for individual room EQ.

Idea #2: It does seem there are potentially some resonances and with the version1 there were driver consistency concerns and thus I am wondering if one should do gated measurements of their own HTM-12 (as I made mine with slightly different dimensions, used constrained layer dampening throughout the box itself, and used different dampening material) and then EQ the high end based on that data and then EQ the low end based on in room response. Do people think that gated measurements on axis would give high enough accuracy for the higher frequencies based on ones specific speaker that this would be the ideal way to EQ their own speaker (resting assured based on the Klippel measurements that the off axis sound and directivity are very well controlled and thus one only needs to worry about the direct sound for generating an eq)?
How low of a frequency could one get with high resolution with gated measurements and would this be enough to bridge down to the Schroeder frequency for in room measurements and EQ?
Does this seem like a reasonable approach and would it have any benefit over idea 1?

Idea #3: Once again relying on the Klippel measurements to assure us there there is very impressive directivity could one use their own measurements (similar to idea 2) and make the speaker fully active and bypass the passive crossover? Unfortunately I do not know enough about making active speakers and thus I assume the crossover point should be kept the same (as the DI seems to match up remarkably well) but as for slopes at the crossover etc that would be out of my current knoledge base. Worth pursuing?

Thoughts?
I am thinking of potentially doing idea 1&2 and then measuring pre and post and seeing the results.... but seeing what other people think before sinking all that time into it and also seeing if going fully active would also be interesting to people / worth pursuing.
 

dorirod

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@hardisj thanks for the review! A minor thing, in the video when you overlay the video on top of the write-up during the CTA-2034 discussion, I would suggest picking the bottom left corner rather than the bottom right as it obstructs important parts of the graph that you're discussing.
 

Rick Sykora

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No. If the port is simply leaking the internal resonance from standing waves then people will think the port is at fault. We won't know for sure unless I plug the port and test which I didn't do for this speaker (but I did do for the Pioneer VM-50 I just posted). So, I hesitate to post nearfield graphics until I have the chance to try it both ways.

Your time ofc. Btw, note only said it could come from the ports. Agree more is needed to determine root cause. :cool:
 

ooheadsoo

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I don't recall the pitch of the howl when I was sanding the boxes, but it was definitely without ports installed.
 

Rick Sykora

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I don't recall the pitch of the howl when I was sanding the boxes, but it was definitely without ports installed.

Lol. From Erin’s measures, looks like a much better speaker than I would have thought. Notably the directivity is better than I expected from a 2-way with a large diameter woofer! Whether midrange resonances can be readily remediated would be really good to know. Might really get it closer to SOTA! :cool:
 
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MZKM

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Preference Rating
SCORE: 3.2
SCORE w/ sub: 5.7

Sensitivity: 91.1dB (300Hz-3kHz ; spec: 96dB)
Frequency response: +/- 6.4dB 55Hz-20kHz


Spinorama 68.png
Horizontal Directivity 58.png
Horizontal Directivity Normalized 61.png
Vertical Directivity 59.png
Vertical Directivity Normalized 59.png
chart 68.png
 

richard12511

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ooheadsoo

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Thanks, Erin. Simple 5 band eq has been generated...now if only I could actually listen at a decent volume.
 

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This is a copy/paste from my site and there may be formatting issues here because of that. You can see the full review on my site.
https://erinsaudiocorner.com/loudspeakers/diysg_htm12v2/

DIYSG HTM-12v2 Speaker Review

  • Saturday, Jun 12, 2021
DSC02003.JPG

Foreword / YouTube Video Review
The review on this website is a brief overview and summary of the objective performance of this speaker. It is not intended to be a deep dive. Moreso, this is information for those who prefer “just the facts” and prefer to have the data without the filler. Discussion about the data and my subjective thoughts can be found in my video below.


For a primer on what the data means, please watch my series of videos where I provide in-depth discussion and examples of how to read the graphics presented hereon.
https://youtube.com/playlist?list=PLnIxFR_ey0b37Ex4KV2mBz-kYB7QLffR1



Information and Photos
The DIY Sound Group HTM-12v2 is a DIY design from Matt Grant which was/is available in kit form from DIYSG.
Note the distinction of this model is “v2” as this is an update that was made from the previous version in 2020. The speaker is ported (front) and the crossover point between the Celestion CDX1-1742 compression driver and the (Eminence made) Denovo 12” Hyperlite™ woofer is specified as 1250Hz. Assembled weight is approximately 36 pounds according to the designer.
Here is a quote from the designer:

The new HTM-12 is the most capable of the current HT(M) lineup and suitable for use in very large home theaters. Even though it’s the largest and most powerful of the HT’s it does so without compromising sound quality. It uses a new Celestion compression driver with a polyimide diaphragm providing smooth yet detailed high frequencies, and the 1.75” voice coil handles extreme dynamics and high output levels with ease. The new 12” Hyperlite™ woofer is the end result of a 1.5 year joint project with Eminence. The Hyperlite features a completely new surround and spider giving the woofer more X-max and lower bass output. Completely frame and cone give a stealth look with no reflections while watching a movie. The Hyperlite™ woofer specs along with its high powered neodymium magnet give this speaker a very well balanced and detailed sound over the bass, mid-bass, and midrange. The large SEOS-15 waveguide has excellent directivity control for a very wide “sweet spot” so everyone hears the same thing without any significant changes in sound no matter where they sit in the room.

A kit for a single speaker (including everything sans enclosure; except for front baffle) was approximately $330.

These speakers were loaned to me by their owner, who built them from the kit. There are no physical or electro-mechanical issues and this unit is a good sample, representative of what one would ideally build from the kit.

DSC02006.JPG





CTA-2034 (SPINORAMA) and Accompanying Data
All data collected using Klippel’s Near-Field Scanner. The Near-Field-Scanner 3D (NFS) offers a fully automated acoustic measurement of direct sound radiated from the source under test. The radiated sound is determined in any desired distance and angle in the 3D space outside the scanning surface. Directivity, sound power, SPL response and many more key figures are obtained for any kind of loudspeaker and audio system in near field applications (e.g. studio monitors, mobile devices) as well as far field applications (e.g. professional audio systems). Utilizing a minimum of measurement points, a comprehensive data set is generated containing the loudspeaker’s high resolution, free field sound radiation in the near and far field. For a detailed explanation of how the NFS works and the science behind it, please watch the below discussion with designer Christian Bellmann:


The reference plane in this test is just below the tweeter, per the designer, Matt.
Measurements are provided in a format in accordance with the Standard Method of Measurement for In-Home Loudspeakers (ANSI/CTA-2034-A R-2020). For more information, please see this link.

CTA-2034 / SPINORAMA:
CEA2034%20--%20DIYSG%20HTM-12%20v2.png



Early Reflections Breakout:
Early%20Reflections.png


Estimated In-Room Response:
Estimated%20In-Room%20Response.png


Horizontal Frequency Response (0° to ±90°):
SPL%20Horizontal.png


Vertical Frequency Response (0° to ±40°):
SPL%20Vertical.png


Horizontal Contour Plot (not normalized):
DIYSG%20HTM-12v2_Horizontal_Spectrogram_Full.png


Horizontal Contour Plot (normalized):
DIYSG%20HTM-12v2%20Beamwidth_Horizontal.png


Vertical Contour Plot (not normalized):
DIYSG%20HTM-12v2_Vertical_Spectrogram_Full.png


Vertical Contour Plot (normalized):
DIYSG%20HTM-12v2%20Beamwidth_Vertical.png




Additional Measurements

Impedance Magnitude and Phase + Equivalent Peak Dissipation Resistance (EPDR)

For those who do not know what EPDR is (ahem, me until 2020), Keith Howard came up with this metric which he defined in a 2007 article for Stereophile as:
… simply the resistive load that would give rise to the same peak device dissipation as the speaker itself.
A note from Dr. Jack Oclee-Brown of Kef (who supplied the formula for calculating EPDR):
Just a note of caution that the EPDR derivation is based on a class-B output stage so it’s valid for typical class-AB amps but certainly not for class-A and probably has only marginal relevance for class-D amps (would love to hear from a class-D expert on this topic).
DIYSG%20HTM-12v2_Impedance_0.1v.png


On-Axis Response Linearity
DIYSG%20HTM-12v2%20FR_Linearity.png

“Globe” Plots
These plots are generated from exporting the Klippel data to text files. I then process that data with my own MATLAB script to provide what you see. These are not part of any software packages and are unique to my tests.

Horizontal Polar (Globe) Plot:
This represents the sound field at 2 meters - above 200Hz - per the legend in the upper left.
DIYSG%20HTM-12v2_360_Horizontal_Polar.png



Vertical Polar (Globe) Plot:
This represents the sound field at 2 meters - above 200Hz - per the legend in the upper left.
DIYSG%20HTM-12v2_360_Vertical_Polar.png



Harmonic Distortion
Harmonic Distortion at 86dB @ 1m:
DIYSG%20HTM-12%20v2%20--%20Harmonic%20Distortion%20%2886dB%20%40%201m%29.png


Harmonic Distortion at 96dB @ 1m:
DIYSG%20HTM-12%20v2%20--%20Harmonic%20Distortion%20%2896dB%20%40%201m%29.png


Harmonic Distortion at 102dB @ 1m:
DIYSG%20HTM-12%20v2%20--%20Harmonic%20Distortion%20%28102dB%20%40%201m%29.png




Cumulative Spectral Decay (CSD)
Cumulative%20spectral%20decay%20DIYSG%20HTM-12%20V2.png


Dynamic Range (Instantaneous Compression Test)
The below graphic indicates just how much SPL is lost (compression) or gained (enhancement; usually due to distortion) when the speaker is played at higher output volumes instantly via a 2.7 second logarithmic sine sweep referenced to 76dB at 1 meter. The signals are played consecutively without any additional stimulus applied. Then normalized against the 76dB result.
The tests are conducted in this fashion:
  1. 76dB at 1 meter (baseline; black)
  2. 86dB at 1 meter (red)
  3. 96dB at 1 meter (blue)
  4. 102dB at 1 meter (purple)
The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components) instantaneously.
DIYSG%20HTM-12v2_Compression.png


Long Term Compression Tests
The below graphics indicate how much SPL is lost or gained in the long-term as a speaker plays at the same output level for 2 minutes, in intervals. Each graphic represents a different SPL: 86dB and 96dB both at 1 meter.
The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components).
The tests are conducted in this fashion:
  1. “Cold” logarithmic sine sweep (no stimulus applied beforehand)
  2. Multitone stimulus played at desired SPL/distance for 2 minutes; intended to represent music signal
  3. Interim logarithmic sine sweep (no stimulus applied beforehand) (Red in graphic)
  4. Multitone stimulus played at desired SPL/distance for 2 minutes; intended to represent music signal
  5. Final logarithmic sine sweep (no stimulus applied beforehand) (Blue in graphic)
The red and blue lines represent changes in the output compared to the initial “cold” test.
DIYSG%20HTM-12v2_Long_Term_86_Compression.png

DIYSG%20HTM-12v2_Long_Term_96_Compression.png




Parting / Random Thoughts
If you want to see the music I use for evaluating speakers subjectively, see my Spotify playlist.
  • Subjective listening was mainly in the farfield at 3-4 meters in an open floorplan living room. Subjective listening was conducted at 80-95dB at these distances and occasionally higher. Higher volumes were done simply to test the output capability in case one wants to try to sit further away.
  • The sensitivity of this speaker is lower than the v1 version by about 3dB (v1 measured at 94dB @ 2.83v/1m, where the v2 measures at 91dB @ 2.83v/1m). In this case, however, I’d happily take the tradeoff of sensitivity for better frequency response. You’re already in the low 90’s and that’s plenty for most home theater setups. The fidelity is better to have than 3dB sensitivity in this case and in my opinion.
  • When listening, I was mostly overall happy with what I heard. The horizontal radiation pattern is fairly narrow (as the data shows) and this tends to keep the speaker from having a very wide soundstage as there is little reflections from the sidewall to help enhance the feeling of spaciousness in the recording. However, some may prefer that (or some rooms may be better served by a speaker like this). The one issue I have - sonically - with these speakers is the amount of lower midrange resonance. This is clearly audible and the CSD data points to the issue being in the ~250Hz region, evidenced by the long settling time of the signal compared to other frequencies. My guess is this is a function of the enclosure height, as the height (25 inches) is equal to a half-wave of about 270Hz. There is another resonance that shows up in the impedance at around 400Hz which seems to also correlate to the width dimension of the enclosure. It is possible additional bracing or simply adding additional acoustic stuffing would remedy these issues.
  • The dynamic range (Instantaneous compression) data hints at some potential areas for improvement.
    • First, at around 1250Hz the compression peaks at about 0.5dB. We know this is the crossover point. The harmonic distortion data also shows an increase there. Most would look at this and think the crossover is too low. But it is important to realize the level of compression we see; it is roughly 0.50dB at 102dB. Is it worth messing up the excellent directivity at the crossover region in order to relax the compression to a smaller number? I don’t think so. But if one wants to put some more money into things, then maybe. Of course, this could be heating of the actual passive components, though my hunch is we would see that show up in the long-term compression tests and we do not.
    • Secondly, there is some funny business going on around 400-500Hz. Looking at the impedance data we can also see some irregularity there evidenced by a “blip”. This indicates a resonance either from the woofer itself or the enclosure. I would have to measure the raw woofer out of the enclosure to know for sure.
    • In the low frequency we see compression increase below about 80Hz but from 80-100Hz the compression is pretty much flat. Around 100-200Hz there is some more compression. This leads me to think we are seeing raw driver effects and simply reaching the limits of what this speaker is capable of on the low end. Even though it is a 12-inch woofer, it is on the higher-side of sensitivity and we expect to lose output on the low end compared to a traditional 12-inch woofer.
  • The high frequency above about 6kHz tends to widen in directivity which means it could potentially sound a bit bright. I’d consider using some acoustic absorption on the sidewalls that would help absorb some of this but I wouldn’t go too thick. I think - and this is pure speculation - that 1-inch thick acoustic paneling on the first reflection points would make a positive difference here. Though, with that said, some people prefer a little bit of treble. In my own opinion, however, this extra “boost” isn’t ideal.
In my opinion, this is a significant step up from the previous “v1” iteration of this speaker.
While the response is not flat by any means, the directivity control of this speaker is excellent. There are midrange nulls - but in every axis. This means that with a little bit of EQ to straighten out the kinks in the midrange, you end up with a speaker that has a more linear response and does so in every axis, spreading the same energy to the sidewalls as it does directly at the listener making for a more pleasant sound for music and home theater alike.

Even in its raw form (without EQ) I’m quite impressed with what this speaker does. If the designer can figure out what is causing the dips mentioned above and can also fix the resonances I am hearing in the low midrange, I imagine this will be a world-class speaker besting what highly-regarded manufacturers produce at a significantly higher cost to the user. However, it should be noted these issues may increase costs. I just imagine what it is capable of with a little more money put into it either via passive components or even DSP.

This is an obvious “recommend” from me given the target, the performance and the potential to be even better with some DSP.


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Hi,

Here is my take on the EQ.

These EQ are anechoic EQ to get the speaker right before room integration. If you able to implement these EQs you must add EQ at LF for room integration, that usually not optional… see hints there: https://www.audiosciencereview.com/...helf-speaker-review.11144/page-26#post-800725


The raw data with corrected ER and PIR:

Score no EQ: 3.1
With Sub: 5.8

Spinorama with no EQ:
  • Not Flat
  • lots of sharp peaks and deeps?
  • Horizontal directivity is great.
DIYSG HTM-12v2 No EQ Spinorama.png

Directivity:
Better stay at tweeter height
Horizontally, anything up to 20deg.
DIYSG HTM-12v2 2D surface Directivity Contour Only Data.png

DIYSG HTM-12v2 LW better data.png

EQ design:

I have generated One EQ. The APO config file is attached.
  • The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment.

Score EQ Score: 5.2
with sub: 7.5

Code:
DIYSG HTM-12v2 APO EQ Score 96000Hz
June172021-134716

Preamp: -2.1 dB

Filter 1: ON HPQ Fc 45.50 Hz Gain 0.00 dB Q 1.25
Filter 2: ON PK Fc 95.00 Hz Gain -4.75 dB Q 2.36
Filter 3: ON PK Fc 176.40 Hz Gain 2.05 dB Q 3.63
Filter 4: ON PK Fc 276.00 Hz Gain -2.00 dB Q 1.18
Filter 5: ON PK Fc 375.00 Hz Gain -2.39 dB Q 4.72
Filter 6: ON PK Fc 457.00 Hz Gain 2.60 dB Q 5.17
Filter 7: ON PK Fc 929.00 Hz Gain -2.24 dB Q 1.94
Filter 8: ON PK Fc 2084.00 Hz Gain -1.34 dB Q 1.27
Filter 9: ON PK Fc 3584.00 Hz Gain -0.70 dB Q 9.27
Filter 10: ON PK Fc 7449.00 Hz Gain -1.10 dB Q 5.40
Filter 11: ON PK Fc 11873.00 Hz Gain -3.67 dB Q 1.51
DIYSG HTM-12v2 EQ Design.png


Spinorama EQ Score
DIYSG HTM-12v2 Score EQ Spinorama.png


Zoom PIR-LW-ON
DIYSG HTM-12v2 Zoom.png


Regression - Tonal flat after EQ
DIYSG HTM-12v2 Regression - Tonal.png


Radar no EQ vs EQ score
Great improvements
DIYSG HTM-12v2 Radar.png


The rest of the plots is attached.
 

Attachments

  • DIYSG HTM-12v2 APO EQ Score 96000Hz.txt
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  • DIYSG HTM-12v2 Vertical 3D Directivity data.png
    DIYSG HTM-12v2 Vertical 3D Directivity data.png
    393.7 KB · Views: 29
  • DIYSG HTM-12v2 Horizontal 3D Directivity data.png
    DIYSG HTM-12v2 Horizontal 3D Directivity data.png
    386.8 KB · Views: 27
  • DIYSG HTM-12v2 Normalized Directivity data.png
    DIYSG HTM-12v2 Normalized Directivity data.png
    317.8 KB · Views: 24
  • DIYSG HTM-12v2 Raw Directivity data.png
    DIYSG HTM-12v2 Raw Directivity data.png
    482.8 KB · Views: 26
  • DIYSG HTM-12v2 Reflexion data.png
    DIYSG HTM-12v2 Reflexion data.png
    154.6 KB · Views: 29
  • DIYSG HTM-12v2 LW data.png
    DIYSG HTM-12v2 LW data.png
    150.8 KB · Views: 28
  • DIYSG HTM-12v2 2D surface Directivity Contour Data.png
    DIYSG HTM-12v2 2D surface Directivity Contour Data.png
    611.5 KB · Views: 31
  • DIYSG HTM-12v2 3D surface Horizontal Directivity Data.png
    DIYSG HTM-12v2 3D surface Horizontal Directivity Data.png
    739.1 KB · Views: 26
  • DIYSG HTM-12v2 3D surface Vertical Directivity Data.png
    DIYSG HTM-12v2 3D surface Vertical Directivity Data.png
    757.7 KB · Views: 27

johnp98

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Hi,
Here is my take on the EQ.
These EQ are anechoic EQ to get the speaker right before room integration. If you able to implement these EQs you must add EQ at LF for room integration, that usually not optional… see hints there: https://www.audiosciencereview.com/...helf-speaker-review.11144/page-26#post-800725

EQ design:

I have generated One EQ. The APO config file is attached.
  • The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment.
Score EQ Score: 5.2
with sub: 7.5
Just wondering if there is any need for the anechoic based EQ in the low frequency (below the rooms schroeder frequency)? Should one just use these measurements above the schroeder frequency and then use the moving mic method below to generate a room specific EQ for the low end?
 

Rick Sykora

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Isn't it ported around 45hz per the impedance plot, or am I reading that wrong? Doesn't seem out of the ordinary.

Not out of ordinary at all, but the left peak is the vent(s) resonance, the minima in between is the box resonance and the right peak is the woofer resonance.

For this speaker, the midrange resonances are likely more audible, but reducing or eliminating would be the desired goal. :cool:
 
Last edited:

ooheadsoo

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Thanks, @Maiky76, trying your EQAPO settings out in lieu of my own.

@johnp98, I imagine the determining factor would be how many bands of EQ you have available.

@Rick Sykora, thanks, I'm not technical enough to understand the EPDR, so hadn't really paid attention to the blips in that curve. They're definitely easier to see than squiggles in the impedance curve.
 

mtg90

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Not out of ordinary at all, but the left peak is the vent(s) resonance, the minima in between is the box resonance and the right peak is the woofer resonance.

For this speaker, the most unusual aspect is the ugly blip at the box tuning. While the upper bass and midrange ones are likely more audible, but reducing or eliminating would be the desired goal. :cool:

What blip at the box tuning? Unless you are looking at the EPDR plot not impedance.

Edit: Any ported speaker will have a similar blip in the EPDR due to the phase angle between the impedance peaks, those blips are not the same as ones in the impeadance graph and do not relate to resonances of the speaker drivers or cabinet. AFAIK these DIYSG speakers are the first ones Erin has calculated EPDR for, other more recent speaker reviews have been powered, so no impedance data.
 
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Rick Sykora

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What blip at the box tuning? Unless you are looking at the EPDR plot not impedance.

Edit: Any ported speaker will have a similar blip in the EPDR due to the phase angle between the impedance peaks, those blips are not the same as ones in the impeadance graph and do not relate to resonances of the speaker drivers or cabinet. AFAIK these DIYSG speakers are the first ones Erin has calculated EPDR for, other more recent speaker reviews have been powered, so no impedance data.

Yes, a few too many lines that are similar shades AND did not see Erin included EPDR. Will retract. :facepalm:
 

Rick Sykora

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Thanks, @Maiky76, trying your EQAPO settings out in lieu of my own.

@johnp98, I imagine the determining factor would be how many bands of EQ you have available.

@Rick Sykora, thanks, I'm not technical enough to understand the EPDR, so hadn't really paid attention to the blips in that curve. They're definitely easier to see than squiggles in the impedance curve.

As @mtg90 mentioned, I did confuse the EPDR and impedance traces. If you are not familiar, EPDR is simply a method for combining the speaker impedance and phase information to represent the effective load to the amplifier. Feel free to ask if you need further explanation.
 

puppet

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Me thinks this project would really shine as an active design.
Eleven filters seems like a lot of eq after the passive corrections for a two way.
 
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