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The Low Frequency Content Thread (films, games, music, etc)

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The surround specific bass boost requires an extremely large boost in order to bring it up to a pretty low level relative to the lfe hence, in this case, even if you have channel specific beq, I suspect you will struggle to notice it. 

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5 hours ago, 3ll3d00d said:

The surround specific bass boost requires an extremely large boost in order to bring it up to a pretty low level relative to the lfe hence, in this case, even if you have channel specific beq, I suspect you will struggle to notice it. 

How would you define "extremely large"?  It's a bit hard to tell from your pictures, but it looks like the green curve  for least one surround channel levels out at around -72 dB (average) below 20 Hz.  To get this content to about the same level as the stuff at 100 Hz (-33 dB) requires up to +39 dB of shelf.  Here's the total shelf gain for each channel for the @maxmercy BEQ correction:

LFE: +20 dB

LCR: +18 dB

SURR: +48 dB (!)

Note that these also use 1st order high pass filters (f0=3.0 Hz for LCR+LFE and f0=10.0 Hz for SURR) to remove DC noise in the track.  I'm pretty sure this BEQ has it covered.  Is +48 dB really an extreme boost?  I don't think so.  One of my other favorite BEQs, which I just watched the other day is for Guardians of the Galaxy:

LFE: +40.5 dB

LCR: +20 dB

SURR: +60 dB (!!)

As a point of note: my processor is connected to the upstream via analog, so I do have to worry about the effect of boost on the analog noise floor.  With the GotG BEQ applied and no sound playing, I get periodic spurts of noise that are enough to register on my Motu 16A display ("-48 dBFS") and to light up the "signal present" lights on my amp.  That's probably only ~1W actually going to the subs, so no worry there.  However unfortunately, even at that extremely low level the ULF output is enough to cause one of my living room windows to make ticking noises.  GRR!!!  Ignoring that though, the above GotG BEQ delivers very excellent sound.

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perhaps this is clearer

before

https://imgur.com/a/lyOBXiQ

after

https://imgur.com/a/n8g8KHe

this is the channel levels on the track so in reality LFE would be another 10dB higher

this is average but the delta between the channels is similar on the peak chart (just much harder to read)

The post beq surround channel looks odd to me (i.e. it is just the filter shape) and it's at a *much* lower level than the LFE and C. Even if there are distinct effects in the surrounds that aren't in any other channel, IMV it's going to be at most a subtle difference.

 

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1 hour ago, 3ll3d00d said:

perhaps this is clearer

before

https://imgur.com/a/lyOBXiQ

after

https://imgur.com/a/n8g8KHe

I assume the after is with the @maxmercy BEQ applied?

Either way, I strongly disagree that the fact that the surrounds have lower average levels means their shape is not audibly important.  Average level depends on short-term level, duration, and frequency of effects.  Most action happens up front and in the center, so it's no surprise that the surrounds have much lower average levels than the fronts.

1 hour ago, 3ll3d00d said:

this is the channel levels on the track so in reality LFE would be another 10dB higher

Yes.  However, without additional information we can't tell how the LFE channel was used.  There's no guarantee that content that's mixed to one or more front/surround channels gets sent to LFE too.  Many strategies are possible, and you can't really tell what was done by looking at either of the PvA curves.

1 hour ago, 3ll3d00d said:

The post beq surround channel looks odd to me (i.e. it is just the filter shape) and it's at a *much* lower level than the LFE and C. Even if there are distinct effects in the surrounds that aren't in any other channel, IMV it's going to be at most a subtle difference.

*Of course* there are distinct effects in the surrounds!   Any sound that gets mixed to the surrounds that has bass will be affected by the filters applied to that channel during production and the BEQ filters applied during playback.  Unless most of that bass was copied to or sent to the LFE channel, an independent channels BEQ will recover ULF in the surrounds that an all-channels BEQ can't.  The result won't be subtle for the discrete surround (and overhead) effects with sub bass, especially given the ~60 Hz filter!

I do agree that the post BEQ surround channel averages look odd, particularly below 30 Hz.  Why do all the surround channel curves converge to one curve below there?  I would not expect that to happen.  The shape of the curves and lack of finer details is also unusual.  It looks like it could be garbage.  Maybe insufficient precision somewhere?  Are you applying the 1st order high pass at 10 Hz?  And is it working correctly?

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10 hours ago, SME said:

I do agree that the post BEQ surround channel averages look odd, particularly below 30 Hz.  Why do all the surround channel curves converge to one curve below there?  I would not expect that to happen.  The shape of the curves and lack of finer details is also unusual.  It looks like it could be garbage.  Maybe insufficient precision somewhere?  Are you applying the 1st order high pass at 10 Hz?  And is it working correctly?

that is strange, I haven't noticed that on any other tracks. It looks like the analysis of the source signal has basically dropped down into the abyss. I'll have to look into that one.

https://imgur.com/a/UoNlJuS

re the rest of the discussion, it seems a bit pointless to discuss further in abstract terms as it hinges on one's definition of subtle vs marked and whether an effect at -x dB is one or the other. 

 

 

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It is not strange that something with +60dB ulf boost on surround channels looks odd, because this is very likely mostly noise.

Keep in mind that no studio or cinema can reproduce low frequencies on the surround channels, whatever is there below around 50hz was never part of the sound design.

The most important to fix is lfe and lcr, that is where the big difference lies. 

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2 hours ago, 3ll3d00d said:

re the rest of the discussion, it seems a bit pointless to discuss further in abstract terms as it hinges on one's definition of subtle vs marked and whether an effect at -x dB is one or the other.

Again I disagree, and I think you're missing something key here.

For any effect that is mixed exclusively to the surround channels and that contains sub bass , the difference between an independent-channels BEQ and all-channels BEQ is whether or not it's filtered at 60-80 Hz.  The all-channels BEQ does boost the low end of the surround channels, but nowhere enough to keep it from rolling off rapidly below 60-80 Hz. I don't think we disagree over whether "filtered at 60-80 Hz" is subtle or not.

To repeat myself, the only real open question is how much of the bass within the sounds mixed to the surround channels was copied to the LFE channel.  To answer that question requires comparing the tracks side-by-side to see what the mixers did.

1 hour ago, Kvalsvoll said:

It is not strange that something with +60dB ulf boost on surround channels looks odd, because this is very likely mostly noise.

To repeat what I wrote above, the total shelf gain recommended by @maxmercy for TLJ was +48 dB and not +60 dB.  The +60 dB for GotG which also recovers meaningful content.

Either way, any attenuation of say 60 dB by a filter should not be enough to force the relevant content into the quantization noise floor unless the tracks are getting down-sampled to less than 24-bits (i.e. 16-bits, -96 dBFS quantization noise floor) somewhere between where the attenuating filters were applied in production and where the BEQ filters are applied on playback.  I believe DTS HD and Dolby TrueHD are always 24-bit.  The rest of the production chain was almost certainly using at least 24-bit precision (probably 32-bit or 64-bit float in the DAWs).  Realize that 24-bit has a quantization noise floor of -144 dBFS.

It's actually quite impressive that I can get away with the +60 dB boost for GotG being that the signal inputs to my processor are analog (unbalanced actually).  The ULF noise floor of my unbalanced analog connections must be in the neighborhood of -100 dBFS.  :)

1 hour ago, Kvalsvoll said:

Keep in mind that no studio or cinema can reproduce low frequencies on the surround channels, whatever is there below around 50hz was never part of the sound design.

This is incorrect because it is outdated, on two accounts.  The situation changed with immersive formats.

First, as I explained in my above posts, Atmos for cinemas (and probably other immersive formats) introduced support for bass management to be used for surround and overhead channels with dedicated "surround subwoofers", preferably located at the sides or rear of the room.   The Dolby specs *require* every screen, surround, and overhead channel to extend to 40 Hz, using bass management as necessary to meet this goal.  I don't know how many dub stages use 40 Hz vs. 30 Hz subs for surrounds, being that the front channels are still run without subs (usually extending to 40 Hz on their own).

Second, cinema Atmos is not compatible with the home Atmos.  This means that *all* Atmos BD and UHD releases are dedicated home mixes or masters.  This work is done in small rooms that mimic home theaters, and I expect all of them use bass management for the overheads and surrounds (and probably fronts too).  The Atmos home format (or rather the equipment that implements it) does not support separate surround subs, so bass managed bass all goes to the one SUB channel, which will almost certainly extend to 30 Hz or below.

Also keep in mind that sound design is a separate step from the mixing.  Most sound design is being done in small room studios where capabilities (for better or worse) are very different from the dub stage.  Some sound designers might even work using sealed subs and small enough rooms to get significant ULF.  But even if they can't hear the ULF on the track, it's not fair to say that it wasn't part of the sound design.  Whether the ULF was part of a recorded or synthesized effect, it originated as part of the design process.  The only question is whether the designers/mixers/directors are able to hear what they've done.

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I see your point where individual bass-eq for all channels including surround is the ultimate solution, and can in some cases be a significant improvement, as when surround effects that has wide frequency range are not mixed in to the lfe channel, and those surround channels are filtered somewhere in the process.

But still, I claim most of the performance gain with bass-eq can be had with beq on the bass-managed signal, which is the only practical solution for most people. Then you miss out the correct correction for surround - as well as lcr - because the adjustments you make are weighted +10dB hot on the lfe channel, giving too little boost on lcr+sr.

In a world where even very, VERY few dedicated enthusiasts knows what bass-eq means, there is a huge potential for improvement that will be possible on most serious systems, because they all have dsp on the bass-system, which can be used to implement BEQ that gives 80-90% of the improvement. Compared to no BEQ, there is a huge improvement still, and the dedicated channels BEQ will only be a small step above that.

40hz or 50hz for surrounds is more like the same, when talking about the real thing, which means full frequency range - full capacity.

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No I am not, and have not been, missing your point. I agree that a per channel solution's should be better and is better in theory. I question whether it is practically that much better in practice on certain tracks (and whether the effort involved in creating the pre channel beq is worth it). I agree it would take a per channel comparison to get a more informed view.

I commented in the first place because of an idle observation (possibly in the avs thread) that the resulting mono tracks don't look that different (presumably because it is dominated by the louder channels). I haven't done any detailed comparison myself though hence why continued discussion in general is a bit pointless :)

I will dig out the relevant graph to illustrate later and see if it matches my initial idle observation.

 

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1 hour ago, Kvalsvoll said:

I see your point where individual bass-eq for all channels including surround is the ultimate solution, and can in some cases be a significant improvement, as when surround effects that has wide frequency range are not mixed in to the lfe channel, and those surround channels are filtered somewhere in the process.

But still, I claim most of the performance gain with bass-eq can be had with beq on the bass-managed signal, which is the only practical solution for most people. Then you miss out the correct correction for surround - as well as lcr - because the adjustments you make are weighted +10dB hot on the lfe channel, giving too little boost on lcr+sr.

I agree with you in part, but I think the differences can be greater than you'd think.  A lot will depend on the particular mix and also the particular playback system and possibly some subjective preference.

In TLJ, the failure to recover ULF from the surrounds is a sin of omission, which is relatively minor.  Yes, it does mean that a spaceship might lose its weightiness as it pans from the front, overhead and to the rear, but at least the sound is not worse than what you started with.   I picked the surrounds in my example because the difference is quite dramatic on paper and is one that we could all agree would be very audible with those discrete surround effects.

However the front LRC channels are another story.  Even though they roll-off at a similar point, their shapes are still quite different from LFE.  So an EQ solution that is optimized to the mono sum average (which is dominated by LFE), could introduce new humps or bumps into the front LRC that weren't there before.  Here's where we *can disagree* about what's audible and what's not.  Though arguing from personal experience, even quite small bumps can be audibly degrading.  Much depends on shape and bandwidth of the feature, in addition to the level, and also ...

Audibility of differences will depend on the playback system.  Systems with substantial bass problems may not reveal degrading resonances as readily.  (That's not a virtue as such systems also fail to reveal a lot of content.)  For example, a BEQ filter applied to front LRC that increases ULF while adding a slight bump around 55 Hz may have a pronounced boom around that area in general, but on a system with a severe boomy room mode at 45 Hz, the problem at 55 Hz may be hardly noticed.  The BEQ might be an unqualified improvement on this flawed system, but on a system with very clean bass response, the 55 Hz bump may be much more obvious and degrading.

If you had to choose between full ULF extension and balanced response between the deep bass, mid-bass, and upper bass, which would you choose?  Personally, I'll take the balanced response over the ULF extension any day.  IMO, the ULF is the least important frequency range.

3 hours ago, Kvalsvoll said:

In a world where even very, VERY few dedicated enthusiasts knows what bass-eq means, there is a huge potential for improvement that will be possible on most serious systems, because they all have dsp on the bass-system, which can be used to implement BEQ that gives 80-90% of the improvement. Compared to no BEQ, there is a huge improvement still, and the dedicated channels BEQ will only be a small step above that.

I believe the notion that "[global] BEQ that gives 80-90% of the improvement" is overly optimistic, but I am also inclined to judge the soundtrack for what it will sound like on a revealing system vs. an "average" one.  So practically speaking, a global BEQ may be an improvement for most people who choose to use it, even if it does degrade other aspects of the bass somewhat.  And I do understand that most people who have EQ capability at all can only use it on the sub output.  I agree many filtered tracks can be improved to an extent with a global BEQ and that it's worth doing even if an independent channels BEQ would sound better.

But I'm skeptical that a global BEQ will always be better than nothing at all.  Focusing only on ULF, a BEQed track will always seem to be an improvement, but if one considers the sound as a whole, BEQ that introduces new bass resonances in some of the channels could end up sounding worse than nothing at all.  Again, a lot is going to depend on the playback system.  When doing these BEQs (whether global or channel-independent), it's very important to listen to the results on a system that is as accurate and revealing as possible.  (This is probably my biggest gripe with the AVSForum thread where it appears BEQs are being developed using all eyes and no ears.)

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1 hour ago, 3ll3d00d said:

No I am not, and have not been, missing your point. I agree that a per channel solution's should be better and is better in theory. I question whether it is practically that much better in practice on certain tracks (and whether the effort involved in creating the pre channel beq is worth it). I agree it would take a per channel comparison to get a more informed view.

I commented in the first place because of an idle observation (possibly in the avs thread) that the resulting mono tracks don't look that different (presumably because it is dominated by the louder channels). I haven't done any detailed comparison myself though hence why continued discussion in general is a bit pointless :)

I will dig out the relevant graph to illustrate later and see if it matches my initial idle observation.

I'm not the least bit surprised that the resulting mono tracks look very similar, even for cases in which the results sound totally different.  In fact, I would expect this to occur especially when people are using your app to create the BEQs visually as opposed to doing it completely blindly and by-ear.

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29 minutes ago, SME said:

I'm not the least bit surprised that the resulting mono tracks look very similar, even for cases in which the results sound totally different.  In fact, I would expect this to occur especially when people are using your app to create the BEQs visually as opposed to doing it completely blindly and by-ear.

Has anyone created a BEQ by ear alone?

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13 hours ago, SME said:

I agree with you in part, but I think the differences can be greater than you'd think.  A lot will depend on the particular mix and also the particular playback system and possibly some subjective preference.

In TLJ, the failure to recover ULF from the surrounds is a sin of omission, which is relatively minor.  Yes, it does mean that a spaceship might lose its weightiness as it pans from the front, overhead and to the rear, but at least the sound is not worse than what you started with.   I picked the surrounds in my example because the difference is quite dramatic on paper and is one that we could all agree would be very audible with those discrete surround effects.

However the front LRC channels are another story.  Even though they roll-off at a similar point, their shapes are still quite different from LFE.  So an EQ solution that is optimized to the mono sum average (which is dominated by LFE), could introduce new humps or bumps into the front LRC that weren't there before.  Here's where we *can disagree* about what's audible and what's not.  Though arguing from personal experience, even quite small bumps can be audibly degrading.  Much depends on shape and bandwidth of the feature, in addition to the level, and also ...

Audibility of differences will depend on the playback system.  Systems with substantial bass problems may not reveal degrading resonances as readily.  (That's not a virtue as such systems also fail to reveal a lot of content.)  For example, a BEQ filter applied to front LRC that increases ULF while adding a slight bump around 55 Hz may have a pronounced boom around that area in general, but on a system with a severe boomy room mode at 45 Hz, the problem at 55 Hz may be hardly noticed.  The BEQ might be an unqualified improvement on this flawed system, but on a system with very clean bass response, the 55 Hz bump may be much more obvious and degrading.

If you had to choose between full ULF extension and balanced response between the deep bass, mid-bass, and upper bass, which would you choose?  Personally, I'll take the balanced response over the ULF extension any day.  IMO, the ULF is the least important frequency range.

I believe the notion that "[global] BEQ that gives 80-90% of the improvement" is overly optimistic, but I am also inclined to judge the soundtrack for what it will sound like on a revealing system vs. an "average" one.  So practically speaking, a global BEQ may be an improvement for most people who choose to use it, even if it does degrade other aspects of the bass somewhat.  And I do understand that most people who have EQ capability at all can only use it on the sub output.  I agree many filtered tracks can be improved to an extent with a global BEQ and that it's worth doing even if an independent channels BEQ would sound better.

But I'm skeptical that a global BEQ will always be better than nothing at all.  Focusing only on ULF, a BEQed track will always seem to be an improvement, but if one considers the sound as a whole, BEQ that introduces new bass resonances in some of the channels could end up sounding worse than nothing at all.  Again, a lot is going to depend on the playback system.  When doing these BEQs (whether global or channel-independent), it's very important to listen to the results on a system that is as accurate and revealing as possible.  (This is probably my biggest gripe with the AVSForum thread where it appears BEQs are being developed using all eyes and no ears.)

Doing a proper bass-eq takes time and effort, and as you do more of them you start to notice that experience is nice to have. Yes, you need to listen, and since a movie is quite long, with lots of scenes and sound effects, this will be a time-consuming process if you want to be sure you get the best possible result within constraints given by you skills and the soundtrack you have. 

But we only watch the movie once - usually. Kind of like how GOT (a person living in Norway) put it about skiing - the conditions really does not matter when climbing and skiing a mountain, because you only ski it once. It is what it is, that one time. If it was perfect, well, good, but if it was icy and crusty, or the bass in the movie was less than perfect in some scenes, that is what we had. But we do not have to re-live it over and over again.

This also means there is a limit to how much effort you want to put into fixing someone else's mistakes on a movie. So I usually end up picking a couple scenes, and do beq on lcr+lfe.

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John Wick Chapter 2 anyone? I checked it out last night and it was pretty damn good! Not much in the way of sub 20hz effects, however the gunshots and music had excellent slam and volume. Also, I think that it is a better and more enjoyable film than the first and one the best action films period. I would definitely recommend checking it out to any bass heads or fans of action movies in general :)

nXAlrTA.png

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https://www.youtube.com/watch?v=4CbLXeGSDxg

Jesus Christ I hope Disney wisen the F up and sort out their movie audio tracks, because this film's bass better be as epic as this trailer is!!!!

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Definitely going to see Mowgli and The Lion King at the Waterloo BFI Imax cinema in London when they come out. It has the biggest screen in the UK and from what I've personally heard (literally, when I saw Jurassic World there!) the best sound system in Britain. They use massive 18" ported subs of course (flat to 20hz with everything below filtered out) but at least they actually playback the LFE channel and the bass content in the front channels. Every other cinema south-east of London where I live do not have subwoofers for the LFE channel, nor do they have adequate bass response from the front channels. As for the surrounds, they usually have JBL 8340s which can do minus 10dbc at 40hz but no bass management with extra subs as per Dolby Atmos specs I'm afraid. Besides, I purchased four JBL 8330s simply for the novelty factor of actually owning real cinema speakers, and I would not recommend buying cinema surrounds. Cinema front speakers aren't too bad though as long as they are bass managed.

End of rant.

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Hello, everyone.

Just thought that you all deserved some clarity on the issue. This recent spate of comments that I left were done during a short phase of ill health (a psychologically manic phase that lasted for one day only) and that now that I am almost completely healthy (and explained what has happened) that I would provide some encouragement to you all. I am fine.

I apologise for any distress or confusion that my comments may or did cause to anyone viewing this forum. Please forgive me if they did.

As for The Lion King, well... hahahaha. I think that the trailer is almost perfectly constructed and that it will be an enjoyable film to experience, however I will; not go to London to see it, pop into the local to view it and that probably buy it on BD and BEQ it.

Thanks everyone who read and will read this. I hope that all of you have a good day. Cheers.

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