G3P Elevated BM & LFE Issue

[ttocs]

G3P Elevated BM & LFE Issue

We’ve been noticing elevated bass with some system configurations and various Sound Fields (audio modes). Leveling the channels proves to be wrong for Bass Managed bass below the crossover settings, and channels setup as Large. FW-2.3 appears to have gone in the wrong direction with regard to this issue. This thread will show what happens under the conditions being tested. 

Many have some confusion about what LFE is and what BASS MANAGEMENT is, and how Speaker Channels setup as Small use the Subwoofer Channels.

Let’s review what makes up surround system bass. Dolby specifies that every Screen Speaker be Full Range and that there be a Screen Subwoofer for the .1 channel. In a 7.1 system there would be 7 full range speakers and a subwoofer for the LFE channel, 7.1. The .1 channel is not for any speaker channel, it’s a unique channel carrying Low Frequency Effects sound. It was never intended to provide bass for small speakers. The bass for channels configured as Small will be provided via a Bass Management system which can manage and combine both LFE and the bass for Small channels into one or more subwoofer channels, or keep them separate in processors like ours.

For the purposes of this thread:
BM = BASS MANAGEMENT will be considered to be bass for any channel configured as SMALL.
LFE will be what it is, the .1 LOW FREQUENCY EFFECTS channel.

The Issue
BM for Small channels is elevated below the XO.

BM levels for Small channels will vary depending on the system configuration.
Processor Levels Settings being equal SPL will NOT result in Small bass levels being correct below the crossover.
LFE level will also vary but will generally remain at a consistent offset from the BM for Small channels.
It does not matter whether User EQ or Dirac EQ is selected, but for now, this discussion is with using USER EQ.

When I say “level” will vary, this is what I mean.
Go into Menu:: Setup:: Speakers:: Preset 1:: Levels and adjust the level for every channel so all channels are the same SPL. Then startup REW to check. What REW reveals is that the levels BELOW the crossover which are directed to a subwoofer are HIGHER than the levels above the crossover. So the subwoofer bass below the crossover setting will be much louder than what the speaker will produce above the crossover setting.

The LFE channel should be +10dB above the level of “Screen Speakers”, so I’m setting the LFE channel measurement at +10dB in the spreadsheets, and all the other channels will be represented by the relative measured level.

Measured Configurations:
All Small Channels, Left Sub Mono
All Small Channels, Left & Center Sub Mono
All Small Channels, Center Sub Mono
All Small Channels, Left Sub Mono, Center Sub LFE
Fronts Large, All Other Channels Small, Left Sub Mono, Center Sub LFE
Fronts Large, All Other Channels Small, Left & Center Sub Mono
Fronts Large, All Other Channels Small, Left Sub Mono
Fronts Large, All Other Channels Small, Center Sub Mono
Fronts Large, All Other Channels Small, Center Sub LFE, This one pushes all bass for Small channels to the Large Fronts.

The system setup is 7.1, the Crossovers set at 200Hz to reduce influence from any speaker at the crossover setting.

After completing the first six groups of measurements I was seeing results that seemed way too goofy, so I re-ran the ones after setting the Fronts as Large, and then doubted how the process was working and started over. During the second session I ran into the same wild results, and decided to be even more methodical about the process and rerun the entire process a third time and used extra precautions like saving and closing REW, then changing the speaker setup for the next group, then changing HDMI inputs away and back to “set” the new speaker settings and lock in the Surround sound field. The results were the same as the first two runs but this time I was certain the results were legit, but a bit shocking.

With the current firmware I’ve had to adjust the Fronts lower than ever before to get them to level the same as the Center channel and the others. This happened with FW-2.2 also, but it was minimal compared to FW-2.3. The levels are as follows:



The exact levels of adjustment aren’t the problem. The problem is that these levels don’t work, they are wrong in practice when sound fields are in use. REW sweeps expose the fact that the actual levels of the channels are not to spec at all. The LFE channel as measured with REW is not +10dB above the other channels, and BM is not at the correct level either. Most of the speaker configurations have BM at +3dB, and LFE at +10dB, and no channels are at 0.0dB where they should be relative to LFE. When the Fronts as configured as Large, BM and LFE have the same relative split of 7dB between them, but now the Fronts are waaaay above where they should be, and this is with the original leveling already severely reduced. The spreadsheet tells the story very well IMO, and is easy to see the relative changes.

This is just with Surround. I’ll be testing the other sound fields in coming days, but this was an eye opener. Since I normally have been using the other Preset with Dirac applied to it, these severely low levels applied to the Fronts have been masked because Dirac levels itself so the Fronts and Subs have needed only a little extra adjustment when I ran REW to confirm the correct levels.

Here are the results for Surround Sound Field.
V1 Measurements

(edit: After running the second round of measurements I realized that some of the formatting might have been confusing so I changed how I presented the subwoofers and now show the BM sub(s) with the Small channels for extra clarity (hopefully). The sub(s) listed at the top provide the LFE channel signal, and the sub(s) listed with the Small channels provide the BM for the Smalls, with the one caveat being #9 where the Large Fronts provide the BM for the Small channels.)

This first set of results took all day to run, simply because I couldn't believe what I was seeing. I may revert back to a previous firmware after running some more sound fields for a sanity check.

[ttocs]

With the above established, I will now show how I adjust the channels to improve the situation which works - mostly, but not entirely. I can bring the levels of the channels providing bass down, but not down far enough for all speaker setups. It'll become clearer once I post the new results tonight.

In the V1 Measurements, Run 9, you can see that the bass for Small channels is 4.5dB above the level of the bass for the Fronts. When the Fronts are adjusted downward, this brings the Small channel bass with it, still showing that there is an issue with elevated bass from the summing of both Fronts producing the bass together.

In V1, Runs 1-4, the adjustment is relatively simple. Just bring the Mono subwoofer channels down the extra 4dB to bring them to match the levels above the XO for the Small channels. This will then negate having used Levels Tones in the processor, effectively the Levels Tone tool is useless, so setting the levels without tones, or with the amps off, is the way to go here. To rub this point in even more, after making these adjustments, using the Tones in Levels will then show the levels of the subwoofers to be "wrong", but they will in fact be "correct", MOST of the time, but not all of the time.

==========================================================================
V2 Measurements 210712. The level for the Left Sub Mono has been corrected using the REW values from V1 as a guide, and the same for the Large Fronts. I didn't do all the same measurement combos this time. The results would be the same offsets, but just at different levels so it's just not worth the effort. With the Left Sub adjusted down, all the Small channel bass is correct and at the same level as above the XO when using Surround. The Center Sub LFE provides the LFE at +10dB above the Left Sub Mono and the Large Fronts, so this is the best workaround for the issue and what I've been using since late last year, although, not with having to adjust the sub and Fronts channels down as far as they are with FW-2.3.

[ttocs]

Reserved for future #2

[marcl]

I have not done the extensive testing that ttocs has done, but we've discussed our observations and they are consistent. This issue started with 2.2 and continued into 2.3 as ttocs says.

My 7.1.4 system has Center Sub=LFE so all LFE goes to a miniDSP feeding two subs. Left and Right Subs=None. Bass Management goes to the L/R Fronts=Large (full range down to below 20Hz, with separate sub feeds). Small speaker crossovers are center=120, surrounds and tops=80.

With 2.2 and 2.3 we have the additional bass boost that ttocs describes in several configurations.  Here's one example from my system.  This happens whether Bass Management goes to large fronts or to subs.  In addition to the bass boost, small speaker bass is unaffected by the speaker's Level adjustment.  For example, with Center Sub=Mono and center speaker crossover at 120Hz, center speaker bass is +5db below the crossover and changing the center Level has no effect below 120Hz.  See the screen shot below ... Left channel in blue; Center with Level 0.0 in green; Center with Level -5.0 in yellow.  



I want to also call attention to another issue that was observed even with 2.1 and occurs with Center Sub=LFE; L/R Subs=None; Fronts=Large. In this configuration Bass Management is sent to the large fronts and since they play the bass in mono all small speaker bass is elevated +3db. This was true on its own before the issues described with 2.2 and 2.3. It is included in some of ttocs' data. The fix for this (in addition to fixing the other bass issues in 2.2/2.3) is for the system to understand how many speakers are playing Bass Management and decrease the level appropriately ... -3db for two fronts or two subs; -6db for three subs. Another way to handle it would be to include a Bass Management Level adjustment similar to the LFE Level that we currently have. 

The net result of all of this is in my system configuration I see flat response with my L/R fronts, and all small speakers bass playing +8db!  What is really unfortunate - in addition to the fact that there is no work-around for this circumstance in 2.2/2.3 - is that general users are being advised to use the "Harman Curves" in Dirac, boosting bass +4 to +8db.  If a user does not measure the system and see this issue, they could end up with >10db bass boost!

Here's an illustration of what my system response looks like with flat Dirac target curves.  I'm showing L, R, C, SL, RL with Psychoacoustic smoothing for clarity.  There is nothing I can do to get a flat nominal response.  (This is irrespective of wanting to add any "house curve")



The issues are serious because they literally could cause system damage for an unknowing user, and at the very least cause users to attribute poor sound to Dirac or the processor when in fact it's a result of multiple processor bugs.

[ttocs]

Some might look at what we are presenting and say, well, why not just raise the levels for all the Small channels to match the subwoofer level? This might put a bandaid on some setups, but nothing will fix the setup with Center Sub LFE and Large Fronts. The Large Fronts will be at whatever level they are, and the summed bass is well above them.

Also, it must never be forgotten that different speaker setups cause the various levels differences, all of which are not seen when we simply use the processor's Levels Tones to adjust our speakers. We "think" it's all the same level, but it's not.

[405x5]

Jul 11, 2021 23:24:14 GMT -5 ttocs said:

G3P Elevated BM & LFE Issue

We’ve been noticing elevated bass with some system configurations and various Sound Fields (audio modes). Leveling the channels proves to be wrong for Bass Managed bass below the crossover settings, and channels setup as Large. FW-2.3 appears to have gone in the wrong direction with regard to this issue. This thread will show what happens under the conditions being tested. 

Many have some confusion about what LFE is and what BASS MANAGEMENT is, and how Speaker Channels setup as Small use the Subwoofer Channels.

Let’s review what makes up surround system bass. Dolby specifies that every Screen Speaker be Full Range and that there be a Screen Subwoofer for the .1 channel. In a 7.1 system there would be 7 full range speakers and a subwoofer for the LFE channel, 7.1. The .1 channel is not for any speaker channel, it’s a unique channel carrying Low Frequency Effects sound. It was never intended to provide bass for small speakers. The bass for channels configured as Small will be provided via a Bass Management system which can manage and combine both LFE and the bass for Small channels into one or more subwoofer channels, or keep them separate in processors like ours.

For the purposes of this thread:
BM = BASS MANAGEMENT will be considered to be bass for any channel configured as SMALL.
LFE will be what it is, the .1 LOW FREQUENCY EFFECTS channel.

The Issue
BM levels for Small channels will vary depending on the system configuration.
LFE level will also vary but will generally remain at a consistent offset from the BM for Small channels.
It does not matter whether User EQ or Dirac EQ is selected, but for now, this discussion is with using USER EQ.

When I say “level” will vary, this is what I mean.
Go into Menu:: Setup:: Speakers:: Preset 1:: Levels and adjust the level for every channel so all channels are the same SPL. Then startup REW to check. What REW reveals is that the levels BELOW the crossover which are directed to a subwoofer are HIGHER than the levels above the crossover. So the subwoofer bass below the crossover setting will be much louder than what the speaker will produce above the crossover setting.

The LFE channel should be +10dB above the level of “Screen Speakers”, so I’m setting the LFE channel measurement at +10dB in the spreadsheets, and all the other channels will be represented by the relative measured level.

Measured Configurations:
All Small Channels, Left Sub Mono
All Small Channels, Left & Center Sub Mono
All Small Channels, Center Sub Mono
All Small Channels, Left Sub Mono, Center Sub LFE
Fronts Large, All Other Channels Small, Left Sub Mono, Center Sub LFE
Fronts Large, All Other Channels Small, Left & Center Sub Mono
Fronts Large, All Other Channels Small, Left Sub Mono
Fronts Large, All Other Channels Small, Center Sub Mono
Fronts Large, All Other Channels Small, Center Sub LFE, This one pushes all bass for Small channels to the Large Fronts.

The system setup is 7.1, the Crossovers set at 200Hz to reduce influence from any speaker at the crossover setting.

After completing the first six groups of measurements I was seeing results that seemed way too goofy, so I re-ran the ones after setting the Fronts as Large, and then doubted how the process was working and started over. During the second session I ran into the same wild results, and decided to be even more methodical about the process and rerun the entire process a third time and used extra precautions like saving and closing REW, then changing the speaker setup for the next group, then changing HDMI inputs away and back to “set” the new speaker settings and lock in the Surround sound field. The results were the same as the first two runs but this time I was certain the results were legit, but a bit shocking.

With the current firmware I’ve had to adjust the Fronts lower than ever before to get them to level the same as the Center channel and the others. This happened with FW-2.2 also, but it was minimal compared to FW-2.3. The levels are as follows:

View Attachment

The exact levels of adjustment aren’t the problem. The problem is that these levels don’t work, they are wrong in practice when sound fields are in use. REW sweeps expose the fact that the actual levels of the channels are not to spec at all. The LFE channel as measured with REW is not +10dB above the other channels, and BM is not at the correct level either. Most of the speaker configurations have BM at +3dB, and LFE at +10dB, and no channels are at 0.0dB where they should be relative to LFE. When the Fronts as configured as Large, BM and LFE have the same relative split of 7dB between them, but now the Fronts are waaaay above where they should be, and this is with the original leveling already severely reduced. The spreadsheet tells the story very well IMO, and is easy to see the relative changes.

This is just with Surround. I’ll be testing the other sound fields in coming days, but this was an eye opener. Since I normally have been using the other Preset with Dirac applied to it, these severely low levels applied to the Fronts have been masked because Dirac levels itself so the Fronts and Subs have needed only a little extra adjustment when I ran REW to confirm the correct levels.

Here are the results for Surround Sound Field.
V1 Measurements
View Attachment

This first set of results took all day to run, simply because I couldn't believe what I was seeing. I may revert back to a previous firmware after running some more sound fields for a sanity check.

“Finding Subwoofer” revisited.
Why are you not maintaining all of your hypothesizing under one thread?
Makes your confusion even more so

[ttocs]

Jul 12, 2021 11:46:57 GMT -5 405x5 said:

“Finding Subwoofer” revisited.
Why are you not maintaining all of your hypothesizing under one thread?
Makes your confusion even more so

This is a firmware bug. I've communicated with Emo on this in the past, but they don't think it's important enough to put at the top of the list, and it has nothing to do with my subwoofer setup.

In point of fact, my subwoofer setup was altered to help alleviate this bug from affecting me as much.

This thread is specifically for this bug.

[geebo]

Jul 12, 2021 11:57:13 GMT -5 ttocs said:

Jul 12, 2021 11:46:57 GMT -5 405x5 said:

“Finding Subwoofer” revisited.
Why are you not maintaining all of your hypothesizing under one thread?
Makes your confusion even more so

This is a firmware bug. I've communicated with Emo on this in the past, but they don't think it's important enough to put at the top of the list, and it has nothing to do with my subwoofer setup.

In point of fact, my subwoofer setup was altered to help alleviate this bug from affecting me as much.

This thread is specifically for this bug.

I get the elevated bass whether using a preset that has one sub or my other preset which has one sub for redirected bass and another for LFE. And it doesn't show up in the levels setting in setup.

[marcl]

Jul 12, 2021 12:14:12 GMT -5 geebo said:

Jul 12, 2021 11:57:13 GMT -5 ttocs said:

This is a firmware bug. I've communicated with Emo on this in the past, but they don't think it's important enough to put at the top of the list, and it has nothing to do with my subwoofer setup.

In point of fact, my subwoofer setup was altered to help alleviate this bug from affecting me as much.

This thread is specifically for this bug.

I get the elevated bass whether using a preset that has one sub or my other preset which has one sub for redirected bass and another for LFE. And it doesn't show up in the levels setting in setup.

Yes it seems that no matter where you send the small speaker bass it is elevated several db, and if you use large fronts for small speaker bass you get +3db more.  And, the Levels in the Preset have no affect on the small speaker bass.

[jbrunwa]

Jul 12, 2021 11:57:13 GMT -5 ttocs said:

Jul 12, 2021 11:46:57 GMT -5 405x5 said:

“Finding Subwoofer” revisited.
Why are you not maintaining all of your hypothesizing under one thread?
Makes your confusion even more so

This is a firmware bug. I've communicated with Emo on this in the past, but they don't think it's important enough to put at the top of the list, and it has nothing to do with my subwoofer setup.

In point of fact, my subwoofer setup was altered to help alleviate this bug from affecting me as much.

This thread is specifically for this bug.

Thanks so much for doing all this tedious diagnostic work!  I had posted on the Dirac Live thread the other week with my REW measurements showing elevated bass, and maybe incorrectly blamed Dirac.

[ttocs]

Jul 12, 2021 13:59:31 GMT -5 jbrunwa said:

Jul 12, 2021 11:57:13 GMT -5 ttocs said:

This is a firmware bug. I've communicated with Emo on this in the past, but they don't think it's important enough to put at the top of the list, and it has nothing to do with my subwoofer setup.

In point of fact, my subwoofer setup was altered to help alleviate this bug from affecting me as much.

This thread is specifically for this bug.

Thanks so much for doing all this tedious diagnostic work!  I had posted on the Dirac Live thread the other week with my REW measurements showing elevated bass, and maybe incorrectly blamed Dirac.

You're welcome!
I purposely left Dirac out of this issue for now because it "can" add or subtract some bass, but it is bass in general, not specifically for BM or LFE - but that also depends on how the system is setup. Dirac would simply be an additional layer of confusion leaving us spinning our wheels a bit. With the USER EQ there is no interference from Dirac. We are simply dealing with Levels on the one hand, but then how BM is poorly handling things with particular sound fields. I feel there's got to be some numbers in the code somewhere telling the bass to be at a certain level and it is this code which needs to be changed.

[marcl]

Jul 12, 2021 13:59:31 GMT -5 jbrunwa said:

Jul 12, 2021 11:57:13 GMT -5 ttocs said:

This is a firmware bug. I've communicated with Emo on this in the past, but they don't think it's important enough to put at the top of the list, and it has nothing to do with my subwoofer setup.

In point of fact, my subwoofer setup was altered to help alleviate this bug from affecting me as much.

This thread is specifically for this bug.

Thanks so much for doing all this tedious diagnostic work!  I had posted on the Dirac Live thread the other week with my REW measurements showing elevated bass, and maybe incorrectly blamed Dirac.

That's a reason why I posted also.  Although my REW plots are with Dirac, the issues are independent of Dirac.  I actually tried to use some modified target curves in Dirac to counteract the issues, but to no avail.

[davidl81]

This bass issue is actually pretty frustrating. It’s clear as day the bass is elevated by 5-8dB and Emotiva does not think it’s a significant issue? Sure I can adjust my sub down every time I watch a movie but that would not be acceptable for a $350 AVR, much less something at this price point. Hopefully Lonnie is working on fishing this.

[ttocs]

Updated first post.

[405x5]

I have manually tweaked the LFE between music and movies ever since I got into this and find that to be a non issue.
Wouldn’t you need to alter the history of recording technology to correct this (seriously)

[davidl81]

Jul 13, 2021 8:39:00 GMT -5 405x5 said:

I have manually tweaked the LFE between music and movies ever since I got into this and find that to be a non issue.
Wouldn’t you need to alter the history of recording technology to correct this (seriously)

I’m not sure how you would think this is a non issue. You go through all of this Dirac setup and then watch a movie and your sub is hitting 6dB too loud. The only way to fix it is to either adjust the trim on the processor each time or turn down the gain on the sub. It’s not some minor difference in low end, it’s an extremely noticeable issue. I have dual S15s and after the firmware update the subs are obnoxious loud. I should be able to set my Dirac curve and not have to make any adjustments after that.

[405x5]

Jul 13, 2021 8:46:10 GMT -5 davidl81 said:

Jul 13, 2021 8:39:00 GMT -5 405x5 said:

I have manually tweaked the LFE between music and movies ever since I got into this and find that to be a non issue.
Wouldn’t you need to alter the history of recording technology to correct this (seriously)

I’m not sure how you would think this is a non issue. You go through all of this Dirac setup and then watch a movie and your sub is hitting 6dB too loud. The only way to fix it is to either adjust the trim on the processor each time or turn down the gain on the sub. It’s not some minor difference in low end, it’s an extremely noticeable issue. I have dual S15s and after the firmware update the subs are obnoxious loud. I should be able to set my Dirac curve and not have to make any adjustments after that.

What happens when you leave Dirac out of the sub. Mix?

[marcl]

Jul 13, 2021 8:46:10 GMT -5 davidl81 said:

Jul 13, 2021 8:39:00 GMT -5 405x5 said:

I have manually tweaked the LFE between music and movies ever since I got into this and find that to be a non issue.
Wouldn’t you need to alter the history of recording technology to correct this (seriously)

I’m not sure how you would think this is a non issue. You go through all of this Dirac setup and then watch a movie and your sub is hitting 6dB too loud. The only way to fix it is to either adjust the trim on the processor each time or turn down the gain on the sub. It’s not some minor difference in low end, it’s an extremely noticeable issue. I have dual S15s and after the firmware update the subs are obnoxious loud. I should be able to set my Dirac curve and not have to make any adjustments after that.

Yes and .... "subs" includes LFE and small speaker bass:  two completely separate sources.  Some of what you hear - possibly most of it - is from the small speaker bass being elevated.  You can lower the overall sub level, but then you lower LFE also.

This is exacerbated by the fact that many people follow Dirac's advice (I do not, BTW) to user their curve to elevate bass, or use the so-called "Harman Curves" to add as much as 4, 6 or 8db to the bass.  You can trim down the LFE with the LFE Level adjustment in the processor, but there's no way to trim down small speaker bass.  

[davidl81]

Jul 13, 2021 8:54:25 GMT -5 405x5 said:

Jul 13, 2021 8:46:10 GMT -5 davidl81 said:

I’m not sure how you would think this is a non issue. You go through all of this Dirac setup and then watch a movie and your sub is hitting 6dB too loud. The only way to fix it is to either adjust the trim on the processor each time or turn down the gain on the sub. It’s not some minor difference in low end, it’s an extremely noticeable issue. I have dual S15s and after the firmware update the subs are obnoxious loud. I should be able to set my Dirac curve and not have to make any adjustments after that.

What happens when you leave Dirac out of the sub. Mix?

Same issue. The bass is pronounced with Dirac enabled or not enabled.

[marcl]

Jul 13, 2021 9:32:14 GMT -5 davidl81 said:

Jul 13, 2021 8:54:25 GMT -5 405x5 said:

What happens when you leave Dirac out of the sub. Mix?

Same issue. The bass is pronounced with Dirac enabled or not enabled.

Yes!  ttocs in his initial post specifically did not use Dirac.  In my posts I have Dirac enabled with flat target curves. The issue is the same.  Changing target curves can make the issues worse, but not better.