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maxmercy

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

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2 hours ago, SME said:

I can agree to your first statements, but I'm confused by what you mean in bold here.  Do you mean to say that there are many more unfiltered movies than it appears because many movies are not measured here?

Yes, good surround mixing is a big plus too, as well as is overall better tonal balance, which also has a big impact on the perception of both bass and ambiance.

Haha. My bad. I think it should have said, "spectrum of movie titles". If all you do is watch rom-com's from the 90's, you're not going to find a lot of ULF. ;)

I'm slowly losing my mind.... it's okay. :lol:

 

I won't say there are "many more" unfiltered movies than umm...filtered movies because I'm starting to wonder if your idea of "unfiltered" means a flat PvA curve...

Everything we hear in movies is 100% studio creation so they are under no obligation to be flat-to-DC type extension in their audio mix in every single release. Is it really a surprise that the overall curve of most movie's bass PvA looks very similar to the capabilities of pro-style cinema sub-bass systems?

 

I agree with your last sentence. :)

 

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2 hours ago, Infrasonic said:

I won't say there are "many more" unfiltered movies than umm...filtered movies because I'm starting to wonder if your idea of "unfiltered" means a flat PvA curve...

Everything we hear in movies is 100% studio creation so they are under no obligation to be flat-to-DC type extension in their audio mix in every single release.

You have a point.  When I said "unfiltered", I left it vague.  The context was ULF, which could be informally taken to be under 20 Hz.  Extension under 20 Hz seems to be pretty rare these days, but there is a decent amount of stuff that reaches to 20 Hz or 25 Hz, as you pointed out.

Of course studios have no obligation to deliver audio that's flat to DC  (or 3 Hz?).  Though it's nice when it happens.  I wish they'd do it more often, for the tactile transducer users among other reasons.  I know a number of cinemas have transducers now.  Although they may be mainly of the "shaker" type with poor extension.

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None of my friends believe the fact that commercial cinemas lack heavily in their bass. Even my old Klipsch 12" sub gave more punch (in my extremely small room of course) than out local theatre. We do however not have any commercial Atmos/IMAX/.. rooms in our area, thats why I'm taking a train to go and see if our "national" IMAX room does it better. 

 

About that EQ mixing, is it complex? I think I would like to try that out for certain movies (The Dark Knight, LOTR Trilogy, and few others come to mind) to ensure the best experience. 

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Commercial cinemas, when designed, implemented, and maintained properly provide a great low frequency experience, similar to a well done live concert.  The caveat is that the experience does not extend much lower than 25-30Hz.  Most impact/slam is between 40-100Hz and even higher in frequency. 

We are freaks here that can monitor and playback the lowest frequencies, that are often taken out of a mix that is CREATED and is meant to be played on a cinema system (25-30Hz vented, high sensitivity subwoofers).    While mixing stages have existed in the past that could monitor into the low teens Hz-wise, most cannot monitor below the high-20s.

We sometimes are surprised by mixes that do not exclude the content below 30Hz, as those mixes are a significantly different experience in a properly equipped home theatre.

Your friends may simply be used to a certain frequency and level of low frequency experience, and call that 'good'.

The EQ mixing described is in the Bass EQ for movies thread on this forum.

JSS

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6 hours ago, maxmercy said:

Commercial cinemas, when designed, implemented, and maintained properly provide a great low frequency experience, similar to a well done live concert.  The caveat is that the experience does not extend much lower than 25-30Hz.  Most impact/slam is between 40-100Hz and even higher in frequency.

Sadly, even a cinema that's "designed, implemented and maintained properly", seems to be a rare occurrence.  While my memory may not be completely reliable, my impression is that cinema sound quality (at least here in the States) has trended worse  over time.  I recall being fairly impressed by new cinemas built in the 90s and early '00s, but newly built/renovated cinemas I've heard in the last few years since are meh at best.

I believe a big part of the issue is the X-curve calibration standard and a shift toward stricter adherence to the target.  The standard actually allows for a +/- 3 dB deviation, which gives a lot of leeway to a calibrator to allow more bass and treble and to smoother the knee at 2 kHz, all while remaining "compliant" with the standard.  However, I suspect this kind of manual tweaking is not done much anymore as cinemas cut labor costs associated with setup and maintenance including calibration work.  Many cinemas are probably calibrated entirely automatically.  I'm not opposed to automation when it actually works, but for audio calibration, current technology is not up to the task.

I'm trying to change the situation by working on better technology.  I have a very novel approach that is showing enormous promise, but it'll probably be at least a year before I can test it outside my own room.  It also remains to be seen how much tweaking it will need to work robustly in a variety of different rooms.  I do have confidence that I could eventually adapt it to work in all kinds of rooms, which would be very exciting.  Then the challenge would be to get the industry to actually update their standards, but in the meantime, it could probably be marketed to cinemas directly where it could provide substantial SQ improvements via download-able X-curve re-EQ meta-data.

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Mr Allen at HPS4000 has been echoing your sentiments for some time:

http://www.hps4000.com/pages/articles_page_.html

Even though he considers <27Hz not part of the audible spectrum (he is not wrong depending on frame of reference, hence his choice on subwoofer low corner), he has some solid ideas in those articles, and addresses many of the things we complain about here.

JSS

 

 

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Those look interesting.  I'll definitely read them when I get the chance.  The first article I opened (most popular) is dated 1998.  Surprise surprise.  This is hardly a "new" problem.

The latest edition of Floyd Toole's Sound Reproduction book also has an entire chapter dedicated to discussing cinema sound where he remarks about the 2 kHz knee among other issues.  Toole is consulting with an industry group that has recently been studying the problem with the aim of eventually establishing new SMPTE standards to address the problems with the X-curve.

Toole's and Harman's recommendation seems to be to calibrate smoothed in-room response to a target that looks more like the Harman curve was is optimized (at least in theory) for "anechoic flat" speaker response cinema rooms and listening distances.  While I think this approach would lead to an incremental improvement, it's still less than ideal.  For starters, when people talk about frequency response, they don't bother to specify *how* the response was smoothed and *what form* was smoothed.  These details actually matter a lot as far as the end result is concerned.

For starters, one can choose a smoothing kernel which can be a flat-top ("moving average"), which is easiest to implement.   Or it might use some kind of curve, for example a gaussian, which provides a smoother looking end result.  As for what form, one can smooth the magnitude, the power, log-magnitude (i.e. the dB value), or the complex amplitude  (where magnitude and phase are treated together as a composite 2D value).  Power smoothing yields results most consistent with RTA and other continuous averaging instruments.  Complex smoothing is actually mathematically equivalent to frequency-dependent window (!).  FWIW from my testing, REW appears to do log-magnitude smoothing with a kernel that's similar to a gaussian.  While it makes the data look prettier, it has a substantial effect on the end product.

Furthermore, I have 99.9% confidence in the fact that fitting in-room response to any kind of target (even a room variable target) is suboptimal.  Smooth in-room response should never occur in practice where any reflections are present, which means that in the process of EQing in-room response to be smooth, one actually introduces harmful resonances.  How ironic!

While  I am a ways away from definitely solving this problem, I get the feeling I'm further along than anyone else at this point.  :)  It sure sounds like it.

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Wow you guys just went from "cool stuff I can understand", to "waay over my head". I'm still into the first stages of learning to control my room with REW/processors so if youre ever (in like 2-3 months when my exams are done again) interested in explaining it all/implementing your technics on my room (measurements) I'm happy to be your test subject! First of I need to correctly setup all the active speakers I just put together (5x 2-way LaScalas) and integrate the 2x new DIY Subs. Using a flat response (based/with pyschoacoustic smoothing) for the moment. The book from Toole you linked seems pretty interesting! Is there somewhere I can read a few samples (like texts like that) online? Maybe some free website?

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10 hours ago, Droogne said:

Wow you guys just went from "cool stuff I can understand", to "waay over my head". I'm still into the first stages of learning to control my room with REW/processors so if youre ever (in like 2-3 months when my exams are done again) interested in explaining it all/implementing your technics on my room (measurements) I'm happy to be your test subject! First of I need to correctly setup all the active speakers I just put together (5x 2-way LaScalas) and integrate the 2x new DIY Subs. Using a flat response (based/with pyschoacoustic smoothing) for the moment. The book from Toole you linked seems pretty interesting! Is there somewhere I can read a few samples (like texts like that) online? Maybe some free website?

Thanks for the offer, but it'll be some time before I'm ready to do serious testing on other systems, at which point I'll need to be present to listen to the results myself.  Of course, if I move to Europe or something, it could happen sooner.

A flat in-room response will probably not give the best sound.  At the very least, you'll probably want 5-6 dB of bass boost centered around 80-160 Hz.  You may also want a more gradual slope (i.e. 1 dB/octave) a ways above and below that point.   Feel free to experiment, of course.

I'm not aware of any online samples from Floyd Toole's book, but if you are curious, I highly recommend buying it.  In my opinion, it's the best book on the subject of sound reproduction, particularly for small room systems.  A lot of stuff in there seemed counter-intuitive to me when I first read about it, but my experience over time as led me to change my mind and conclude it was correct.

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8 hours ago, SME said:

Thanks for the offer, but it'll be some time before I'm ready to do serious testing on other systems, at which point I'll need to be present to listen to the results myself.  Of course, if I move to Europe or something, it could happen sooner.

Haha completely understandable! But if you do have some things for me to try out (which I can measure / give a subjective listening to).

8 hours ago, SME said:

A flat in-room response will probably not give the best sound.  At the very least, you'll probably want 5-6 dB of bass boost centered around 80-160 Hz.  You may also want a more gradual slope (i.e. 1 dB/octave) a ways above and below that point.   Feel free to experiment, of course.

Well I will definetely try that out, I havent really done experimenting with that kind of stuff so thanks.

8 hours ago, SME said:

I'm not aware of any online samples from Floyd Toole's book, but if you are curious, I highly recommend buying it.  In my opinion, it's the best book on the subject of sound reproduction, particularly for small room systems.  A lot of stuff in there seemed counter-intuitive to me when I first read about it, but my experience over time as led me to change my mind and conclude it was correct.

Well I'm very interested (have seen his name pass a few times), so might buy it :) 

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Also, on topic: 

One of the more terrifying ULF effects/sounds I have heard in all my listening sessions is definitely the opening song of Flume's latest album "Skin": Helix. It has that slow build up, and a heavy (+20hz) drop, but oh boy between that there was one moment which pushed my sub to all it's limit. Pretty scary!            

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12 hours ago, Droogne said:

Also, on topic: 

One of the more terrifying ULF effects/sounds I have heard in all my listening sessions is definitely the opening song of Flume's latest album "Skin": Helix. It has that slow build up, and a heavy (+20hz) drop, but oh boy between that there was one moment which pushed my sub to all it's limit. Pretty scary!            

Is the YouTube version sanitized or something?  Just going by ear here, but I'm not noticing much bass at all.  There seems to be a tiny amount of content around 20 Hz, but otherwise it's just mid-bass and at fairly moderate level.  It sure has a lot of distortion though.  If that music is pushing your sub too hard, you don't want to even try playing a movie until you figure out what's wrong.

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5 minutes ago, SME said:

Is the YouTube version sanitized or something?  Just going by ear here, but I'm not noticing much bass at all.  There seems to be a tiny amount of content around 20 Hz, but otherwise it's just mid-bass and at fairly moderate level.  It sure has a lot of distortion though.  If that music is pushing your sub too hard, you don't want to even try playing a movie until you figure out what's wrong.

Well I listened to the FLAC version, so I'll try out the YouTube version tomorrow to compare ! :)

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On 4/18/2018 at 9:14 PM, maxmercy said:

Mr Allen at HPS4000 has been echoing your sentiments for some time:

http://www.hps4000.com/pages/articles_page_.html

Even though he considers <27Hz not part of the audible spectrum (he is not wrong depending on frame of reference, hence his choice on subwoofer low corner), he has some solid ideas in those articles, and addresses many of the things we complain about here.

JSS

 

 

Interesting read, thanks. I have read a few articles from John Allen over the years, though I had not read the "Missing" article before. I concur that distortion makes a source seem louder than it actually is, and that people need to use their ears and not their eyes listening to sound.

 

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On 3/31/2018 at 2:35 PM, maxmercy said:

In short, it is a quieter, but very dynamic track that doesn't clip.

Hi max, long time no see.  Hope you're doing well as well as the rest of you guys here on DB.  I found something that I think is pretty cool that might interest you.  It's a VST plugin (typically used in DAW's for recording) by iZotope that takes a clipped signal and "de-clips" it: 

5add5b7cc5c65_RXDe-Clip.png.2962cca6ec2a12a04e57aac5a2e8cc12.png

 

For example I put down a bass part and intentionally clipped it:

5add5a65ae99f_Farclipshot.thumb.PNG.05c252fcf9b802ee0cc959189e3dd40a.PNG

 

Close up of the clipped signal:

5add5bf935e99_Closeclipshot.thumb.PNG.98b119056a6ffc8d0b493c2d20bd5a1f.PNG

 

After applying the de-clipper:

5add5c1b3d2ca_FarDe-Clipped.thumb.PNG.c2a6b4f04fced3a3508398c2e8e21971.PNG

 

After de-clipping zoomed in:

5add5c3cc1c12_CloseDe-Clipped.thumb.PNG.859e4837452a03d3ce6d28be56c85d38.PNG

 

Anybody who was bothered by a clipped soundtrack could put the separated channels into a DAW like Audacity, apply this, export it to disc and then apply max's BEQ to it to bring out the best of the low stuff.  Just an idea...  I know that it's a lot of work and that the production houses should just give us a proper product but it is what it is. 

 

Anyway, keep cool fellas... let the bass be with you and whatnot. 

 

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Good to see you here!

Interesting...

Can you run the same audio through Audacity's Clip Fix plugin and see if you get similar results?  I think Clip Fix runs a bezier fit, this looks similar.

JSS

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Interesting comparison of the declipper function Shred. Could you hear a difference? I know it might be difficult on some very short transient peaks but just wondering. 

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Unfortunately the de-clip does not work.

Clipping is usually caused by lower frequency transients, and when the signal clips, a very noticeable duration of higher frequency content is lost, and this can not be accurately restored. Some more advanced plugins may have algorithms that try to restore by estimating what should be there, by looking at previous and after signal content, but it will not be possible to restore the content completely. 

For the lfe channel a declip can work better, but it requires gain adjustment to make room for the recovered transients, so  the overall level will be reduced, and there is no gain in transient impact before gain is restored by increasing gain later in the chain.

Clipping is annoying and destructive for sound quality because of the harmonics that are introduced. For lfe, the lfe signal will always be filtered somewhere later, so the destructive effect is not so severe. And a clipped transient will add up to 3dB headroom, you can see this by low-pass filtering a clipped signal, the result will look like a de-clipped signal and it will have a higher peak amplitude.

 

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I would add that the low-pass filter on the LFE channel will tend to soften any clipping that's present there anyway.

The most offensive clipping is that which occurs on the mains channels, but I have found that the relative offensiveness of the clipping depends a lot on the quality of the playback system.  If the playback system has sufficient headroom, a good balance between low and high frequencies, and no substantial mid or high frequency resonances, then most clipping is likely to be fairly inoffensive.

My older playback systems likely suffered from all three of these deficiencies, and clipping in movies tended to be quite offensive to the ears.  With my system now, and especially if reshape the response (where necessary) to compensate content created for X-curve calibrated systems, most clipping I hear just sounds kind of like a dirty recording, as though some of the signal isn't getting through.  The sound quality is still obviously degraded, but it doesn't offend the ears like it did before.

It also seems like most movies these days use soft limiting and/or compression instead of hard clipping like in the bad ole' days.  That's good because most people have playback systems that are not so forgiving.

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On 4/24/2018 at 12:52 PM, Ricci said:

Interesting comparison of the declipper function Shred. Could you hear a difference?

The clipping was pick attack so yeah, it sounded less harsh when de-clipped and played by itself but once the bass was put in the mix and EQ'd, it's pretty hard to tell a difference. 

 

You still playing these days?  Any new recordings or vids? 

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On ‎5‎/‎12‎/‎2018 at 2:08 PM, Shredhead said:

The clipping was pick attack so yeah, it sounded less harsh when de-clipped and played by itself but once the bass was put in the mix and EQ'd, it's pretty hard to tell a difference. 

 

You still playing these days?  Any new recordings or vids? 

Yep still playing. Practicing 3 total days a week with 2 groups. Shows peppered in there as well. Wrapping up an EP recording etc...

PM me your email and I'll try to send you a few tracks.

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