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Hot and Cold

Commercial subwoofers have volume limiting circuitry to protect the driver from overzealous mixing by some DVD producers, and from ham-fisted users.
In the DIY world, most of us are limited to plate amplifiers which don't have limiters, so we have to be a bit careful.
This page details which DVDs are mixed hot, and which are mixed cold, and covers a 16dB range.
It might just save you some grief.
When I first play a new DVD, I set the sub boost at around the middle of the range, say +6dB. When a loud section is encountered, I fine tune the setting. By the end of the movie, I've settled on a value for the highest safe boost. This is then written on a sticker for next time I play the movie.
These are all standard definition Region4 (Australia) releases, played back using the Dolby digital soundtrack, with all speakers set to small (ie Bass from mains redirected to sub in addition to LFE signal)

 

Safe boostMovie
-4dBShottas - Those Jamaican's must like their sun, because this one is mixed WAY TOO HOT
-3Harsh Times
-2
-1
0 Catch A Fire
Ronin
Star Wars: Episode II - Attack of the Clones
Con Air
Flight of the Phoenix
1
2 I, Robot
Running Scared
LOTR: The Two Towers - Extended Edition
Pirates of the Caribbean: Dead Man's Chest
The Wrong Man
3 Terminator 3: Rise of the Machines
The World's Fastest Indian
Jarhead
Master and Commander: The Far Side of the World
The Assassin
Finding Nemo
4 Donnie Darko
War of the Worlds
Pearl Harbor
Kokoda
The Incredibles
The Chronicles of Narnia: The Lion, the Witch and the Wardrobe
Batman Begins
LOTR: The Return of the King - Extended Edition
The Long Kiss Goodnight
5 The Three Burials of Melquiades Estrada
Crank
Backdraft
6 Casualties of War
Mystic River
Star Wars: Episode I - The Phantom Menace
Hellboy
Star Wars: Episode III - Revenge of the Sith
Children of Men
Hoffa
World Trade Centre
Cars
Underworld
The Astronaut's Wife
7 Black Hawk Down
Sky Captain and the World of Tomorrow
The Deer Hunter
8 Close Encounters of the Third Kind
Earthquake
Die Another Day
Constantine
9Open Range
10 Mad Max
LOTR: The Fellowship of the Ring - Extended Edition
Steamboy
Taugukgi (Brotherhood of War)
The Abyss
11
12Das Boot - Appropriately for a submarine movie, this is mixed WAY TOO COLD

 

Wouldn't it be nice if DVDs had a sticker like this

Subwoofer Safe sticker

You would know that you could set your sub 4dB higher than normal without running into trouble. In my library this sticker is on the "Pearl Harbour" DVD, with "Star WarsII" as the reference getting zero
Any takers for starting a "Subwoofer Safe" campaign?

 

Waterfall Plots and Spectrographs

These examples give an idea the challenges your sub woofer would face in each of the scenes
Here are two ways to visualise what the signal going to the subwoofer looks like:

Waterfall plots show frequency spectrum over time. Intensity is shown as vertical component. Time is bottom (earliest) to top (most recent). Frequency shown left-to-right Software used is SpectraPlus and is a 30-day trial

Spectrographs convey the same information as the waterfall plots. Intensity is shown as a color, with Blue being quiet and red being loud. Time and Frequency as per the Waterfall plots. Software used is Spectrum Laboratory and is freeware

 

Star Wars2 - Ch3 - Ship explodes on landing pad - 107dB

You can see why this is loud. Not only is it mixed the loudest, but look at the spread. No matter how good your sub is, this one has something for you

  

 

Pearl Harbour -Ch22 - Bombing of Battleship Arizona - 105dB

Something for everyone. Huge spread means that even those without subs will get a bang. Really good subs will find that ridge off to left which goes down well below 20hz

  

 

LOTR-Two Towers - Ch41 - Blocks landing after Helms Deep wall blown - 104dB

Strong component below 20hz. This is why some retailers demo their more expensive subs with this sequence

  

 

LOTR - Return of the King - Ch28 - Block lands from catapult - 104dB

Portion below 10hz probably an algorithm artifact. This is one of my favourites. Plenty at 25hz where my sub goes to. Lots more available for those with deeper pockets

  

 

James Bond Die Another Day - Ch4 - Hovercraft crashes into building - 106dB

Very little below 20hz, most from 30hz up. Would sound OK on most subs - mass market mix

  

 

James Bond Die Another Day - Ch1 - Surf sequence - 100dB

Good spread of frequencies will perform on all subs. Consistent level means I use this one for calibration

  

 

Star Wars I -Ch3 - Ship attacked in hold and explodes - 104dB

Woooaaah - reach for the checkbook. You want deep performance to get the best outta this one. Still, there's plenty for everyone!

  

 

Terminator3 - Ch12 - Crane smash - 104dB

Some signal below 20 but most above. Will render well with most subwoofers. Mixed with the mass market in mind

  

 

LOTR - Fellowship of the Ring - Ch29 - Troll first appears in Moria fight - 103dB

Some good 30hz bass. Something here for all subs

  

 

Earthquake - Ch8 - When quake begins- 96dB

Vintage film with nothing below 25hz. Not much of a challenge

  

 

Open Range

Opening Thunderclap


Thunder ("big un's coming...")


Gunfight

 

Comparison of selected scenes

This next graph has a lot of information. These curves are not an instantaneous snapshot - each curve is derived from the entire sequence using the Peak Hold feature. Each curve was individually snapped into Paintshop, so don't think you can get this graph without some work

The curves have been shifted vertically to remove the "boosted" settings, so this is what your sub will see with the volume controls left unchanged



 



Remember that the Threshold of Audibility increases as frequency decreases.
For most of these graphs to be 90db at 15hz, the SPL higher up in the spectrum would be threatening to your hearing, your house and your wallet!
For example, The Bond Hovercraft crash is about 70dB @15hz. If you raise this to 90dB in order to be audible, then the loudest part of the spectrum, around 40hz, will be a very loud 121dB

 

If you would like to see charts for more movies, several of the forums have threads:
AVSForum (Spectrographs)
Home Theater Forum (Spectrographs)
SVS Site (Waterfall plots)
The Bass Archives (Spectrographs for DVDs and Music tracks)
Whilst we're talking about DVD's, check out AmateurHomeTheater where you'll find lots of movie related info

If you're still looking for content to show off your subwoofer, and reckon it can handle the pace, visit Danley Sound Labs and grab their demo files. Make sure you read the warning about dynamic range, as these files have the potential to deliver your cone firmly into the wall opposite your sub.....
If you have a sub that will get down to single digits - note this is not for normal subs - you could get the Ultra-LFE tracks for the rotary woofer from Eminent Technology. Again, do read the warnings on their site! To find out more about the rotary sub, check out the seriously impressive Thigpen build log. Technical info here

 

Just for fun - The best two films in each of my top 30 categories

CategoryBest MovieRunner-up
ActionShoot em upDeath Race
AnimationThe IncrediblesMonsters, Inc.
AnimeSpirited AwayHowl's Moving Castle
AustralianThe PropositionRabbit-Proof Fence
BoxingCinderella ManGirlfight
Bruce WillisThe Wrong ManHudson Hawk
Cohen BrothersBlood SimpleFargo
ComedyConeheadsHot Fuzz
CopsThe WireCopland
CrimeEastern PromisesThe Departed
De NiroTaxi DriverRaging Bull
DocumentaryThe BridgeLong Way Round
DrugsSpunMidnight Express
Future DecayBlade RunnerMad Max
GangstersThe SopranosUnderbelly
HorrorResident EvilBlade
Martial ArtsHeroHouse of Flying Daggers
MummiesBubba Ho-tepThe Mummy
Nicholas CageBringing Out the DeadLeaving Las Vegas
PrisonGhosts of the Civil DeadThe Shawshank Redemption
Sci-FiConstantineAeon Flux
Serial KillersDexterWolf Creek
Spike LeeBamboozledDo the Right Thing
SuperheroesHellboyBatman Begins
TarantinoTrue RomancePulp Fiction
Tom HanksThe TerminalForrest Gump
Toni ColletteMuriel's WeddingDirty Deeds
WarBand of BrothersFull Metal Jacket
WesternsDeadwoodOpen Range
Will SmithI, RobotHancock

 

You can help to improve this site - use the feature request page to suggest changes to content or navigation.      Updated 19th May 2009