Making Room Correction and Bass Management Filters with REW

[hulkss]

I do not trust anything to work correctly regarding computer audio, so, after importing the filters into my XMC-2, I did a filter export and compared the files. All of the filter coefficients matched. Good so far.

I then did a measurement into the left HDMI input channel, measuring the left output for the left speaker and the center subwoofer output for the subwoofer. For this measurement, the left speaker size is set to its normal value of "small" so the subwoofer output gets the left channel rerouted bass through the bass management crossover filter.

REW has a command to "Generate measurement from filters". Using this I can directly compare the REW "theoretical" filter response to the actual filter response measured from the XMC-2.

Nice!  The filters in the XMC-2 are pretty much in exact agreement with REW:

[ttocs]

Dec 3, 2023 16:08:18 GMT -5 hulkss said:

I do not trust anything to work correctly regarding computer audio, so, after importing the filters into my XMC-2, I did a filter export and compared the files. All of the filter coefficients matched. Good so far.

I then did a measurement into the left HDMI input channel, measuring the left output for the left speaker and the center subwoofer output for the subwoofer. For this measurement, the left speaker size is set to its normal value of "small" so the subwoofer output gets the left channel rerouted bass through the bass management crossover filter.

REW has a command to "Generate measurement from filters". Using this I can directly compare the REW "theoretical" filter response to the actual filter response measured from the XMC-2.

Nice!  The filters in the XMC-2 are pretty much in exact agreement with REW:

I'm McLovin' your tutorial!

I've also found that REW is very good at predicting the outcome.

[hulkss]

It's time now for some acoustic measurements to set time alignment and loudspeaker levels. Sweep measurements in REW with a timing reference are required. Your filters should be installed on all channels.

First, be sure to zero the levels and distance settings in the XMC-2.

Put the mic in the center of the seating area at ear level (it does not have to be where anybody actually sits).

Set your subwoofer to the gain level you prefer (you can use the XMC-2 level setting here if needed). You will be setting your other speakers in relation to the Sub for level and timing. Set your test volume and leave it the same for all measurements.

Mute or disconnect your left speaker and send a signal on the left channel to measure the sub (left rerouted bass will go to the sub).

Mute or disconnect the sub and measure the left speaker.

In the EQ target settings click on "Generate measurement from target shape".

You should have three measurements at this point in the "All SPL" panel.

In Measurement Actions use SPL Offset to align the Target Measurement with the Subwoofer Measurement level (don't adjust the Subwoofer level).

In Actions, open the Alignment Tool (this is one of the best features of REW). Adjust the Gain of the Left Speaker Measurement to align with the Target Measurement. Now adjust the delay of the left speaker to align the crossover. I usually check the box to invert the sub and adjust for the largest null and then uncheck invert. Be careful not to get a full wavelength away from the correct setting. The delay distance should make sense. The delay could be negative if the sub is closer to the mic than the left speaker.

[hulkss]

The gain settings from the alignment tool can be directly entered into the XMC-2 level settings for all speakers.

The REW delay distances need to be converted for the XMC-2. First, I list all my delays from the alignment tool in inches. Maintain symmetry if your speaker positions are symmetrical relative to the mic position. Mine are:

Subwoofer = 0" (the reference)
L & R = 28"
C = 39"
Ls & Rs = 53"
Lsr & Rsr = 75"

To get correct distances for the XMC-2, subtract each REW delay distance from the longest one. The shortest speaker distance will get delayed to match the longest distance by the XMC-2.

Sub =         75-0 =   75   = 6' 3"
L & R =       75-28 = 47  =  3' 11"
C =              75-39 = 36 =   3' 0"
Ls & Rs =   75-53 = 22 =    1' 10"
Lsr & Rsr = 75-75 =  0      0' 0"

[hulkss]

I just did a moving mic measurement in the theater seats to confirm the performance of the filter set developed per the process outlined here. It is everything I could hope for in terms of the results matching what was targeted. The crossover performance between subwoofer and front speakers close to perfect. Now on to some listening. The XMC-2 is a great processor that really can deliver high end performance.

I hope that readers of this thread can benefit from it and that there will be some questions and dialog on this topic.

If you're wondering how the bass can be flat to 14 Hz with no EQ filters below 40 Hz? This is achieved with a DIY infinite baffle subwoofer array using 8 15" drivers. It can scare people.

[PaulBe]

Thanks Brad. Nice presentation.

I have a few questions:
1. In your pic of ‘LFE Input channel Measurement’ – The graph shows a rising phase plot with the attended phase wrap. I would have expected a falling phase.  What am I missing?
2. Is it possible to present a system phase plot and group delay plot for your results?
3. What are the actual distances of your speakers from MLP?  I want to make sure I understand your delay/distance process.
4. What do you get when you combine F-22's, motorcycles, and HT?

Agreement about Subs - There is no replacement for displacement.

An infinite baffle for 8 15” Subs is a heroic effort.  Would you be willing to describe your setup?  How is your Sub array physically distributed?

[hulkss]

Dec 4, 2023 8:05:07 GMT -5 PaulBe said:

Thanks Brad. Nice presentation.

I have a few questions:
1. In your pic of ‘LFE Input channel Measurement’ – The graph shows a rising phase plot with the attended phase wrap. I would have expected a falling phase.  What am I missing?
2. Is it possible to present a system phase plot and group delay plot for your results?
3. What are the actual distances of your speakers from MLP?  I want to make sure I understand your delay/distance process.
4. What do you get when you combine F-22's, motorcycles, and HT?

Agreement about Subs - There is no replacement for displacement.

An infinite baffle for 8 15” Subs is a heroic effort.  Would you be willing to describe your setup?  How is your Sub array physically distributed?

1. Good catch. There was an error in the timing offset. I updated the graph.
2. Plots below of the Left channel plus subwoofer with XMC-2 PEQ correction filters:





3. The physical distances to acoustic centers:

Sub =         14' 3"
L & R =       11' 11"
C =              11' 0"
Ls & Rs =    9' 10"
Lsr & Rsr = 8' 0"

4.  Have fun at work and play. There is a post about the subwoofer in the Emotiva Lounge subwoofer board DIY Infinite Baffle Subwoofer.

[hulkss]

After a few hours of listening I have to say my audio system has never sounded better.

All of my previous filter sets for this system were developed using FIR filters. I tried linear phase, mixed phase, and minimum phase. I used FIR Designer, Audiolense, Dirac, or Acourate software. They all work well.

I think a difference here is that I used the moving mic measurement that ignores the phase response and instead provides great spacial averaging. The correction filters are few, simple, and low "Q". The sound is now very smooth, clean and non-fatiguing to listen to at high volume.

REW also provided the means necessary to get the Subwoofer crossover implemented with great precision and time alignment at the crossover point.

[PaulBe]

Dec 4, 2023 17:15:48 GMT -5 hulkss said:

Dec 4, 2023 8:05:07 GMT -5 PaulBe said:

Thanks Brad. Nice presentation.

I have a few questions:
1. In your pic of ‘LFE Input channel Measurement’ – The graph shows a rising phase plot with the attended phase wrap. I would have expected a falling phase.  What am I missing?
2. Is it possible to present a system phase plot and group delay plot for your results?
3. What are the actual distances of your speakers from MLP?  I want to make sure I understand your delay/distance process.
4. What do you get when you combine F-22's, motorcycles, and HT?

Agreement about Subs - There is no replacement for displacement.

An infinite baffle for 8 15” Subs is a heroic effort.  Would you be willing to describe your setup?  How is your Sub array physically distributed?

1. Good catch. There was an error in the timing offset. I updated the graph.
2. Plots below of the Left channel plus subwoofer with XMC-2 PEQ correction filters:





3. The physical distances to acoustic centers:

Sub =         14' 3"
L & R =       11' 11"
C =              11' 0"
Ls & Rs =    9' 10"
Lsr & Rsr = 8' 0"

4.  Have fun at work and play. There is a post about the subwoofer in the Emotiva Lounge subwoofer board DIY Infinite Baffle Subwoofer.

Thanks for the addition data.  Is there a functional difference between using your reference ‘0’ distance technique from using actual physical distance for distance settings in the XMC-2? I.E., does the XMC-2 processor produce a latency difference between the two techniques?

I assumed the processor creates a reference ‘0’ for the longest speaker distance when making relative distance calculations. I don’t know this.

My 2 equidistant closed box 24” Subs are between L&C and C&R. I set the Sub distance at 1’ longer than the physical distance from MLP in my RMC-1L distance settings. It places the Sub timing closer in the mix. This seems to match better by ear.

[hulkss]

Dec 5, 2023 10:58:06 GMT -5 PaulBe said:

Is there a functional difference between using your reference ‘0’ distance technique from using actual physical distance for distance settings in the XMC-2? I.E., does the XMC-2 processor produce a latency difference between the two techniques?

I assumed the processor creates a reference ‘0’ for the longest speaker distance when making relative distance calculations. I don’t know this.

My 2 equidistant closed box 24” Subs are between L&C and C&R. I set the Sub distance at 1’ longer than the physical distance from MLP in my RMC-1L distance settings. It places the Sub timing closer in the mix. This seems to match better by ear.

Only the difference between the distances matters to the XMC-2.

If you enter 10', 13', 20', 30' into the XMC-2, then to get delays (in terms of distance) each speaker distance will be subtracted from the longest distance:

30-10 = 20' of delay for the speaker at 10' to get it to 30'
30-13 = 17' of delay for the speaker at 13' to get it to 30'
30-20 = 10' of delay for the speaker at 20' to get it to 30'
30-30 = 0' of delay for the speaker already at 30'

It can be confusing because REW works with delay and the XMC-2 is starting with distance to calculate delay.

Physical distances are a somewhat crude approximation for aligning a Subwoofer crossover. Use the alignment tool in REW. After you enter distances in to the XMC-2, do sweep measurements and use the alignment tool again. It will show the speakers in time alignment with no changes needed if the distances entered have resulted in the correct time delays.

[hulkss]

I mentioned in an earlier post that I would discuss the LFE channel low pass filter and some concerns related to it.

This filter does have one potential advantage. It keeps LFE bass in phase with rerouted bass from other channels. I have all of my speakers set at " small" & 100 Hz. The crossover is set at 24 dB/oct which effects the low pass only. Here is a plot of the LFE low pass and the base management low pass. They are very similar. This will keep any correlated bass signals between LFE and other channels in phase with no unwanted cancellations. The LFE channel is not supposed to have the same bass as other channels but it happens on some program material.



Now for the problems:

1. For signals input on the LFE channel we are losing bass content. Down 4 dB already at 80 Hz. Bummer.
2. All filtered out content is going nowhere. We just lose it.

I have many concert videos on blu-ray disk. The recording engineers should not be using the LFE channel for music, but they do. Many times there is higher frequency content that is important. A common example is an LFE channel containing Drum or Bass Guitar tracks that have not been processed to put the higher frequencies somewhere on the front channels. In this case the filter on the LFE input removes and discards signal content that is very important to the soundtrack. Some processors, those by Genelec for example, have an option to redirect the high frequency content on the LFE channel to the front center speaker. This works great and would be a good option for Emotiva to implement.

What to do?
I mix the LFE channel into the center channel in my HTPC and do not use the LFE channel. The  XMC-2 LFE filter is avoided and the XMC-2 Bass Management takes care of routing all bass, now including LFE, to the subwoofer. The down side is dropping 10 dB of digital gain on non-LFE channels to match levels to the LFE before mixing.

Results:
This sounds really good. Only one movie (The Dark Knight) had noticeable high-frequency junk on the LFE channel. Low pass filter the LFE before mixing if that happens.

[PaulBe]

Dec 6, 2023 20:40:10 GMT -5 hulkss said:

I mentioned in an earlier post that I would discuss the LFE channel low pass filter and some concerns related to it...

Some thoughts. Please correct anything I misunderstand.

My memory is that the LFE channel in the RMC is supposed to have a low pass filter @ 250Hz. I recall this was stated by Emotiva somewhere on the boards here. No printed spec for it. Obviously your measurements show something else; it looks close to a LR 24dB/Oct roll off at 100Hz. I say there should be no roll off in the LFE channel. The LFE channel is not spec’d for only sub bass, even though this is how it’s predominately used.

Managed/rerouted bass will roll off at the frequency and slope picked in the menu, if the driver doesn’t roll off first. I can pick a frequency that is well above or well below the LFE roll off. Rerouted bass roll off shouldn’t need to be matched to LFE roll off. LFE roll off should be determined by LFE content – Not the processor. Rerouted bass and LFE should simply be mixed.

Assuming perfect responses, if LFE and rerouted bass is correlated then the only workable solution is a 24dB/Oct. low pass Sub crossover @ 100Hz. And, only if your satellites are a Butterworth response closed box -3dB at 100Hz.

I have a number of recordings where the LFE and other channel bass seem to be correlated. I emphasize ‘seem to be’. I think I would have to record the channels in a DAW and visually determine what is happening. An effect could be intended or could be a mistake. I won’t say the LFE channel shouldn’t be used.

I have one recording that surely is a mistake. It’s a Dolly Parton 5.1 SACD “Little Sparrow”. The LFE channel is correlated with the upright Bass and is about 10dB hot.

I think there is a lot of stupid in the recording business. We shouldn’t have to use special processing to try and fix industry recording mistakes. The consumer becomes a paying Guinee Pig for the MIC – Music Industrial Complex. Thankfully there are some fine recordings being made.

I have The Dark Knight. I will play it paying attention to the LFE channel. What on earth was Christopher Nolan thinking?

~~~

All this being said - Bass management (rerouting) is not the critical feature to me that it is for most people. My solution is to use it with the lowest crossover frequency possible, and only on LCR and heights - When I use it. My 7 base channels have the same drivers, and the high resistance aperiodic boxes are -3dB at 42Hz. When I use rerouting, I set the Sub crossover at 40Hz.  They are virtually closed boxes for audible audio frequencies.

I mostly prefer to run all the base channels full range. This eliminates a lot of problems and potential problems. I ran my height channels full range for a long time. There is very little low bass recorded in the height channels.

[hulkss]

Dec 7, 2023 10:36:30 GMT -5 PaulBe said:

First, let's be clear that there are two data streams going to the subwoofer output on the XMC-2. Low Frequency Effects from the LFE channel input and rerouted bass from the other channels that have speakers set to "small".

Recommended practice for the recording studio says:
The LFE channel should not contain signal content that is correlated with the other channels and it should be limited to a maximum of 120 Hz. The LFE channel signal is mixed expecting +10 dB of analog gain above the other channels.

There is nothing preventing recording engineers from using the LFE channel improperly if they choose to.

My memory is that the LFE channel in the RMC is supposed to have a low pass filter @ 250Hz. I recall this was stated by Emotiva somewhere on the boards here. No printed spec for it. Obviously your measurements show something else; it looks close to a LR 24dB/Oct roll off at 100Hz. I say there should be no roll off in the LFE channel. The LFE channel is not spec’d for only sub bass, even though this is how it’s predominately used.
The LFE channel in playback devices should not have a low pass filter unless it is optional and used for the purpose of removing issues with signal content that sounds bad during playback. On music recordings the LFE channel many times (by not following recommend practice) contains valuable content like bass guitar or drums with the full frequency content of those instruments.

Most subwoofers do not play mid bass very well and may be positioned where the higher frequencies are localized and ruin a good acoustic image. So, here we are with a low pass filter on the LFE channel in the XMC-2.

Managed/rerouted bass will roll off at the frequency and slope picked in the menu, if the driver doesn’t roll off first. I can pick a frequency that is well above or well below the LFE roll off. Rerouted bass roll off shouldn’t need to be matched to LFE roll off. LFE roll off should be determined by LFE content – Not the processor. Rerouted bass and LFE should simply be mixed.
Rerouted Bass has to be treated different than LFE. It is from a crossover filter and must recombine in your listening space with the channel it came from. A two-way speaker, for example, has now become a three way speaker. That is the reason for all of the careful crossover filtering and time alignment that I described earlier.

Assuming perfect responses, if LFE and rerouted bass is correlated then the only workable solution is a 24dB/Oct. low pass Sub crossover @ 100Hz. And, only if your satellites are a Butterworth response closed box -3dB at 100Hz.
There are other ways to deal with this problem. I have attached a paper on the subject below.

I have a number of recordings where the LFE and other channel bass seem to be correlated. I emphasize ‘seem to be’. I think I would have to record the channels in a DAW and visually see what is happening. An effect could be intended or could be a mistake. I won’t say the LFE channel shouldn’t be used. I have one recording that surely is a mistake. It’s a Dolly Parton 5.1 SACD “Little Sparrow”. The LFE channel is correlated with the upright Bass and is about 10dB hot. I think there is a lot of stupid in the recording business. We shouldn’t have to use special processing to try and fix industry recording mistakes. The consumer becomes a paying Guinee Pig for the MIC – Music Industrial Complex. Thankfully there are some fine recordings being made.

Many times there is good wide frequency music content on the LFE channel (this usually happens on concert recordings). The XMC-2 filters out this "out of spec sound" and discards it. A proper solution is to use a bass management crossover on the LFE channel and redirect the upper LFE frequencies to the front center channel. This puts the same filtering on the LFE channel and the "small" channels. To achieve this solution today, I mix the LFE channel into the front center channel and empty the LFE channel using my HTPC. This is before the signal goes to the XMC-2. It works perfectly.

Attachments:

Bass Cancellation.pdf (693.86 KB)

[ttocs]

Dec 7, 2023 12:44:09 GMT -5 hulkss said:

A proper solution is to use a bass management crossover on the LFE channel and redirect the upper LFE frequencies to the front center channel. This puts the same filtering on the LFE channel and the "small" channels. To achieve this solution today, I mix the LFE channel into the front center channel and empty the LFE channel using my HTPC. This is before the signal goes to the XMC-2. It works perfectly.

This is intriguing. I like it! Thanks!

[hulkss]

Dec 7, 2023 13:10:25 GMT -5 ttocs said:

Dec 7, 2023 12:44:09 GMT -5 hulkss said:

A proper solution is to use a bass management crossover on the LFE channel and redirect the upper LFE frequencies to the front center channel. This puts the same filtering on the LFE channel and the "small" channels. To achieve this solution today, I mix the LFE channel into the front center channel and empty the LFE channel using my HTPC. This is before the signal goes to the XMC-2. It works perfectly.

This is intriguing. I like it! Thanks!

This is what it looks like using a VST plug-in in REAPER. All channels other than LFE must be lowered 10 dB in level (closest setting in this little plug-in is -9.8 db).

r

[PaulBe]

Dec 7, 2023 12:44:09 GMT -5 hulkss said:

Dec 7, 2023 10:36:30 GMT -5 PaulBe said:

First, let's be clear that there are two data streams going to the subwoofer output on the XMC-2. Low Frequency Effects from the LFE channel input and rerouted bass from the other channels that have speakers set to "small".

Recommended practice for the recording studio says:
The LFE channel should not contain signal content that is correlated with the other channels and it should be limited to a maximum of 120 Hz. The LFE channel signal is mixed expecting +10 dB of analog gain above the other channels.

There is nothing preventing recording engineers from using the LFE channel improperly if they choose to.

My memory is that the LFE channel in the RMC is supposed to have a low pass filter @ 250Hz. I recall this was stated by Emotiva somewhere on the boards here. No printed spec for it. Obviously your measurements show something else; it looks close to a LR 24dB/Oct roll off at 100Hz. I say there should be no roll off in the LFE channel. The LFE channel is not spec’d for only sub bass, even though this is how it’s predominately used.
The LFE channel in playback devices should not have a low pass filter unless it is optional and used for the purpose of removing issues with signal content that sounds bad during playback. On music recordings the LFE channel many times (by not following recommend practice) contains valuable content like bass guitar or drums with the full frequency content of those instruments.

Most subwoofers do not play mid bass very well and may be positioned where the higher frequencies are localized and ruin a good acoustic image. So, here we are with a low pass filter on the LFE channel in the XMC-2.

Managed/rerouted bass will roll off at the frequency and slope picked in the menu, if the driver doesn’t roll off first. I can pick a frequency that is well above or well below the LFE roll off. Rerouted bass roll off shouldn’t need to be matched to LFE roll off. LFE roll off should be determined by LFE content – Not the processor. Rerouted bass and LFE should simply be mixed.
Rerouted Bass has to be treated different than LFE. It is from a crossover filter and must recombine in your listening space with the channel it came from. A two-way speaker, for example, has now become a three way speaker. That is the reason for all of the careful crossover filtering and time alignment that I described earlier.

Assuming perfect responses, if LFE and rerouted bass is correlated then the only workable solution is a 24dB/Oct. low pass Sub crossover @ 100Hz. And, only if your satellites are a Butterworth response closed box -3dB at 100Hz.
There are other ways to deal with this problem. I have attached a paper on the subject below.

I have a number of recordings where the LFE and other channel bass seem to be correlated. I emphasize ‘seem to be’. I think I would have to record the channels in a DAW and visually see what is happening. An effect could be intended or could be a mistake. I won’t say the LFE channel shouldn’t be used. I have one recording that surely is a mistake. It’s a Dolly Parton 5.1 SACD “Little Sparrow”. The LFE channel is correlated with the upright Bass and is about 10dB hot. I think there is a lot of stupid in the recording business. We shouldn’t have to use special processing to try and fix industry recording mistakes. The consumer becomes a paying Guinee Pig for the MIC – Music Industrial Complex. Thankfully there are some fine recordings being made.

Many times there is good wide frequency music content on the LFE channel (this usually happens on concert recordings). The XMC-2 filters out this "out of spec sound" and discards it. A proper solution is to use a bass management crossover on the LFE channel and redirect the upper LFE frequencies to the front center channel. This puts the same filtering on the LFE channel and the "small" channels. To achieve this solution today, I mix the LFE channel into the front center channel and empty the LFE channel using my HTPC. This is before the signal goes to the XMC-2. It works perfectly.

Yep. There are two data streams. I understand the difference between LFE and rerouted bass, and how they have to be treated.

I understand that using a Sub with a 2-way makes it a 3-way.

Recording engineers can do some strange things. There is usually a producer that at least helps keep things on 'track'. Putting the wrong data on a track is noticeable. Often by design, a multi-channel concert has little information in the center channel - just a little fill. 

I have a number of concerts on disc. Could you mention some of your concerts with these issues? I might have a copy to examine this problem.

[hulkss]

Dec 7, 2023 14:37:57 GMT -5 PaulBe said:

Often by design, a multi-channel concert has little information in the center channel - just a little fill.

Why??
Most Recording Studios assume you have a lame center speaker, so, they don't use the center channel like a main channel. This is a MAJOR obstacle that makes it impossible to achieve a great sound stage for ALL seats in your theater.

First off, a virtual center channel (stereo) is totally lame. It only works for a person sitting equidistant from the Right and Left Speakers. Others just hear a comb filtered mess. If significantly seated to the side, that poor person, in addition to comb filtering, hears a totally distorted sound stage with center sound on the closest side. Most people just accept these issues as "the way it is".

How to fix a lame center channel mix:
First, mix the center channel into the right and left channels. This is easy. Drop the center channel level 3 dB and add it to R & L. Do this before the LFE fix I posted if you're using that.



Now we have to make a proper center channel. I have tried many products and CenterOne works best. This renders an absolutely beautiful center channel with no artifacts and acceptable latency. The manual is attached below.

I turn the center channel down 10 db here. I'm going to mix it with the LFE later (LFE fix posted earlier) and would have to turn it down 10 db anyway. This also prevents clipping of the center channel when it renders the center channel. If you're not doing the LFE fix, just lower the Level trim slider -3 dB. We already dropped the Center level -3 dB in the remix.

This is an absolutely amazing repair of lame audio mixes. Center localization will be perfect in all seats.

Attachments:

Manual-CenterOne.pdf (575.38 KB)

[PaulBe]

Dec 7, 2023 15:57:11 GMT -5 hulkss said:

Dec 7, 2023 14:37:57 GMT -5 PaulBe said:

Often by design, a multi-channel concert has little information in the center channel - just a little fill.

Why??

Because it's by design. Most of the recordings in the world are still 2-channel stereo. A lot of classical recordings are done with a spaced pair of omnis or a coincident pair of cardioids.  There are a lot of marvelous stereo recordings and they don't need to be fixed. Altering a good stereo recording will not fix anything, though you may like the alteration. If the stereo recording uses phasing effects in L&R you may harm more than help.

I don't find it to be lame, or an issue, or in need of repair. There is only one good seat in the house... any house... with any number of channels. A movie theater has only a few ideal seats.  Most times I listen to stereo and multi-channel music in a non-ideal location and I don't feel the poorer for it. I can hear the qualities of good and bad recordings from various listening locations. The sweet spot is the best, with any recording.

A proper center channel can be phantom or real. In the end, they are both illusions of reality. Some people prefer a phantom center. I'll take both. You and I are fortunate that our respective LCR are the same speakers.

A great stable soundstage can be had by cross aiming the L&R.

~~~

I have a number of concerts on disc. Could you mention some of your concerts with LFE issues? I might have a copy to examine this problem.

[hulkss]

Dec 7, 2023 17:04:48 GMT -5 PaulBe said:

I have a number of concerts on disc. Could you mention some of your concerts with LFE issues? I might have a copy to examine this problem.

In a very quick look, I took some concert recordings and played the LFE channel into the RTA of REW for 200 averages (32K FFT).
The levels are adjusted for clarity. They will all be compromised by the XMC-2 LFE filter. Godsmack will be affected the least.
What is on that Slayer LFE? It's some of the tracks from the drum kit. Sounds great if you can play it.
Pink Floyd has the synth on there. John Mayall has the bass guitar on LFE.

The others have a strong low pass filter in play.

[hulkss]

Dec 7, 2023 17:04:48 GMT -5 PaulBe said:

Dec 7, 2023 15:57:11 GMT -5 hulkss said:

Why??

Because it's by design. Most of the recordings in the world are still 2-channel stereo. A lot of classical recordings are done with a spaced pair of omnis or a coincident pair of cardioids.  There are a lot of marvelous stereo recordings and they don't need to be fixed. Altering a good stereo recording will not fix anything, though you may like the alteration. If the stereo recording uses phasing effects in L&R you may harm more than help.

I don't find it to be lame, or an issue, or in need of repair. There is only one good seat in the house... any house... with any number of channels. A movie theater has only a few ideal seats.  Most times I listen to stereo and multi-channel music in a non-ideal location and I don't feel the poorer for it. I can hear the qualities of good and bad recordings from various listening locations. The sweet spot is the best, with any recording.

A proper center channel can be phantom or real. In the end, they are both illusions of reality. Some people prefer a phantom center. I'll take both. You and I are fortunate that our respective LCR are the same speakers.

A great stable soundstage can be had by cross aiming the L&R.

I shared your opinion until I found a good solid working improvement to the issue. If you try the center channel fix, you and your guests sitting off center will be amazed. CenterOne does not alter the sound stage as perceived from a center seat. It is not confused by phasing effects. Its main purpose is to provide a three channel feed for further processing in a recording studio or mastering lab. Enough on that.