whats the point in having more than 1 really good subwoofer? - AVS Forum
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post #1 of 54 Old 03-15-2013, 10:28 PM - Thread Starter
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I dont see the point in more than 1 good subwoofer maybe someone can inform me otherwise.

If you played pink noise through your system from 20hz-20000hz at volume level 10 or 15 or whatever then in a good system your frequency response is flat and your tweeter is playing 85 decibels your midrange is playing 85 decibels and your subwoofer should be playing 85 decibels and no component of your audio system should be louder than the other in other words your system is equalized flat.

It seems like if your listening to a song or watching a movie at volume level 15 the original source material when multiplied by the volume level in a accurate system wants you to play a person talking at 90 decibels a siren in the background at 70 decibels and an explosion in the 20-25 hz range at 95 decibels.

So why have 8 subwoofers making that explosion at 110 decibels when youre not accurately reproducing the movie the way the director intended which is to play the explosion at 95 decibels. Of course the decibel is dependent on your volume level.


In other words why do people want their systems to inaccurately play their movies and have the explosions be louder than the source material wants and overpower your mids and highs?
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post #2 of 54 Old 03-15-2013, 10:49 PM
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If you set the subs up properly they're at the right level (at least at the main listening positions) altho some do like to run their subs a bit "hot". Multiple subs even out frequency response more easily in many rooms, as the room is the biggest factor. If one can have 8 subs, one should. smile.gif Makes the bass that much more delicious and effortless....

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post #3 of 54 Old 03-15-2013, 10:57 PM - Thread Starter
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Originally Posted by lovinthehd View Post

If you set the subs up properly they're at the right level (at least at the main listening positions) altho some do like to run their subs a bit "hot". Multiple subs even out frequency response more easily in many rooms, as the room is the biggest factor. If one can have 8 subs, one should. smile.gif Makes the bass that much more delicious and effortless....

That still doesnt make sense im going to have to assume 1 tc sounds lms ultra 5400 equalized flat versus 8 lms ultra 5400 both playing 100 decibels at 20 hertz in an average room will sound the same there isnt that much distortion on a sngle lms 5400 theres no such thing as an easier sound there either is distortion or there isnt.

Saying 8 lms 5400s will sound more "delicious" or "effortless" than a single ls 5400 at 100 hz in a normal room playing 105 decibels while both are equalized is like saying these speaker wires made my system danceable theres no merit to that statement.


And playing 120 decibels is ridiculous because if your equalized flat then your other speakers will be so loud that more than a few minutes at that level and youll lose your hearing.
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post #4 of 54 Old 03-15-2013, 11:02 PM
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Depends on your room and at what points in the room you're measuring for. I'm talking about at the listening position(s) that multiple subs are more beneficial in terms of making it easier to achieve even frequency response. Lower distortion, more headroom come along with that but more about getting even frequency response throughout the room more easily. I'm not a DIY guy and one 5400 is a hell of a lot of sub but I'd still go multiple if I could.

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post #5 of 54 Old 03-15-2013, 11:10 PM
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You are really asking two questions:

1. Do multiple subs help your system produce a flat frequency response in your room?

2. Why do people like to run their subs "hot" (i.e. louder than the rest of the freq spectrum)?

Answers:

1. Yes, multiple subs do help your system produce an even freq response in room. Most rooms create dips and peaks in the bass frequency range. Having multiple subs helps to even out the peaks and valleys, giving a flatter frequency response. You generally need bass eq to get flat bass response, but even with eq it sometimes (not always, but often) takes multiple subs to avoid response dips.

And secondly, let's say you get lucky and you can get flat bass response with one sub and eq. The response will only be flat in one position. If you sit in another seat, or even move your head just a few inches, the response will no longer be flat. Multiple subs help to flatten the response across multiple listening positions, too.


2. Bass is visceral. And an even bass response, elevated in level a bit, sounds good to many people. Note that this is quite different than the "boomy" bass you get when a narrow frequency peak is elevated (although even that can have some limited appeal, it gets old fast). I sometimes run my bass "hot" because it's fun.

-Max
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post #6 of 54 Old 03-15-2013, 11:20 PM
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Originally Posted by ComputerTech0903 View Post


And playing 120 decibels is ridiculous because if your equalized flat then your other speakers will be so loud that more than a few minutes at that level and youll lose your hearing.

The nature of music and movies is that they have peaks that are far louder than the average signal level. So you might be watching a movie or listening to music or a movie at 90db, which is loud but tolerable, and there will be 120db peaks. Your system will sound best if those peaks aren't clipped or distorted by inadequate subs (or speakers).

-Max
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post #7 of 54 Old 03-15-2013, 11:36 PM - Thread Starter
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Originally Posted by maxcooper View Post

The nature of music and movies is that they have peaks that are far louder than the average signal level. So you might be watching a movie or listening to music or a movie at 90db, which is loud but tolerable, and there will be 120db peaks. Your system will sound best if those peaks aren't clipped or distorted by inadequate subs (or speakers).

-Max

120 decibels will kill your hearing do you realize thats 5 decibels louder than sandblasting or a loud rock concert? Your neighbors would call the cops at 110 decibels.

And how confusing is it to have 8 subwoofers in a square around you. Remember subwoofer singnals are mono its not surround it would be confusing hearing a mono sound coming from 8 directions its like if you heard the drip of water coming from 8 directions at once its confusing.

So a 8 subwoofers or 4 subwoofers or 2 subwoofers positioned in different areas of the room would be confusing and b 1-2 high quality subs with enough power will have such low distortion and enough power when properly configured you dont need any more "headroom" because remember headroom actually stands for something and thats distortion and power

In 2 channel music you dont have 4 speakers representing each channel surrounding you for a "flatter response" so why should a mono channel subwoofer be any different.

Its ridiculous no matter how you put it.

So its not ok for 2 channel music to have 8 speakers surrounding you for 2 channel audio for a flatter response but it is ok to have a one channel mono subwoofer signal split to 8 subwoofers surrounding you all around the room?
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post #8 of 54 Old 03-15-2013, 11:40 PM
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Well first off, 10 subwoofers doesn't overpower my mains.

and secondly, your ears don't hear in a scientifically flat way, like Term-Lab mics do.



also, for every doubling of distance or room volume you need infinitely more SPL just to reach the same volume level.

also, most regular theaters use 4-8 subwoofers; and you probably walked away saying 'wow the bass was pretty weak in there' LOL wink.gif
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post #9 of 54 Old 03-16-2013, 12:01 AM - Thread Starter
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Originally Posted by BassThatHz View Post

Well first off, 10 subwoofers doesn't overpower my mains.

and secondly, your ears don't hear in a scientifically flat way, like Term-Lab mics do.



also, for every doubling of distance or room volume you need infinitely more SPL just to reach the same volume level.

also, most regular theaters use 4-8 subwoofers; and you probably walked away saying 'wow the bass was pretty weak in there' LOL wink.gif




4-8 subwoofers and how many cubic feet is a movie theater agan? And what drivers and watts rms are being used in conjuction with their max power handling and sensitivity? they probably dont have 8000 watts rms pumping out.

No matter how you put it its ridiculous having 10 subwoofers its utterly obserd. No one on these forums has a room big enough that needs 10 subwoofers 1-2 max.

Sure 10 subwoofers but you dont need them all theyre probably running at 10% full load so its just to say mine is bigger at that point 10 subwoofers isnt overpowering your mains if theyre only putting out 95 decibels accumulative the point is you could acheive the same sound with 1-2 subwoofers and that 10 subwoofers is unnecessary
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post #10 of 54 Old 03-16-2013, 12:02 AM
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Originally Posted by ComputerTech0903 View Post

In 2 channel music you dont have 4 speakers representing each channel surrounding you for a "flatter response" so why should a mono channel subwoofer be any different.

So its not ok for 2 channel music to have 8 speakers surrounding you for 2 channel audio for a flatter response but it is ok to have a one channel mono subwoofer signal split to 8 subwoofers surrounding you all around the room?

My system has stereo bass in music-mode and tri-channel bass in movie-mode, not mono... but my system isn't normal nor cheap, to say the least.
and yes you 'can' hear the difference between stereo and mono bass, but it requires actually having a stereo bass setup to notice the difference and the appropriate source material. You can't say it doesn't if you haven't ever heard it reproduced as such (it requires at least decent headphones).
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post #11 of 54 Old 03-16-2013, 12:03 AM
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Originally Posted by ComputerTech0903 View Post

120 decibels will kill your hearing do you realize thats 5 decibels louder than sandblasting or a loud rock concert? Your neighbors would call the cops at 110 decibels.

And how confusing is it to have 8 subwoofers in a square around you. Remember subwoofer singnals are mono its not surround it would be confusing hearing a mono sound coming from 8 directions its like if you heard the drip of water coming from 8 directions at once its confusing.

So a 8 subwoofers or 4 subwoofers or 2 subwoofers positioned in different areas of the room would be confusing and b 1-2 high quality subs with enough power will have such low distortion and enough power when properly configured you dont need any more "headroom" because remember headroom actually stands for something and thats distortion and power

In 2 channel music you dont have 4 speakers representing each channel surrounding you for a "flatter response" so why should a mono channel subwoofer be any different.

Its ridiculous no matter how you put it.

So its not ok for 2 channel music to have 8 speakers surrounding you for 2 channel audio for a flatter response but it is ok to have a one channel mono subwoofer signal split to 8 subwoofers surrounding you all around the room?

So what exactly is the point of your thread? You asked a question, people give their opinions and you try to shoot down what they say?

This is a great site with literally TONS on info from some pretty smart people in the industry. Try using the search option and do a little digging and you'll find all the answers you're looking for.

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post #12 of 54 Old 03-16-2013, 12:04 AM
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Yup, continuous 120db is really loud and may damage your hearing in less than a minute. But that's not what we're talking about.

I think I got the +30db peaks thing wrong -- THX says its +20db for peaks. So, if you want to listen at a really loud 100db continuous average level, which the occupational health folks say you can do for 15 minutes before you risk possible hearing damage, you need a system that can play 120db to avoid clipping the peaks. That's really loud, but I'm just trying to point out that if you want clean playback at Xdb average level, you need a system that can reproduce the peaks at (X+20)db.

Bass is non-localizable. It won't sound like its coming from 8 places if you have 8 subs in your room. It will just sound like bass. It won't be confusing.

-Max
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post #13 of 54 Old 03-16-2013, 12:07 AM - Thread Starter
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Originally Posted by BassThatHz View Post

My system has stereo bass in music-mode and tri-channel bass in movie-mode, not mono... but my system isn't normal nor cheap, to say the least.
and yes you 'can' hear the difference between stereo and mono bass, but it requires actually having a stereo bass setup to notice the difference and the appropriate source material. You can't say it doesn't if you haven't ever heard it reproduced as such (it requires at least decent headphones).

That doesnt make sense. Dolby truehd is 5.1 you cant have trichannel base when the .1 stands for 1 channel there is no true tri channel mode.

Sure getting a crossover and spliting a 2 channel signal in to low mids and highs so your mains play the mids and high and a crossover for each channel splits it so you have one subwoofer for each channel is fine but thats not the same thing.
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Originally Posted by maxcooper View Post

Yup, continuous 120db is really loud and may damage your hearing in less than a minute. But that's not what we're talking about.

I think I got the +30db peaks thing wrong -- THX says its +20db for peaks. So, if you want to listen at a really loud 100db continuous average level, which the occupational health folks say you can do for 15 minutes before you risk possible hearing damage, you need a system that can play 120db to avoid clipping the peaks. That's really loud, but I'm just trying to point out that if you want clean playback at Xdb average level, you need a system that can reproduce the peaks at (X+20)db.

Bass is non-localizable. It won't sound like its coming from 8 places if you have 8 subs in your room. It will just sound like bass. It won't be confusing.

-Max

Ughh thx level is 85 decibels with 20 decibel peaks not 100 decibels and 20 decibels for peaks.

Go ask thx what they think about 120db for peaks theyd laugh at you and by the way 85 decibels with 105 decibels for peaks isnt linear with 100 decibels and 120 decibels for peaks the difference between 85 decibels and 105 decibels is substantially and i mean substantially different than 100 decibel to 120 decibel. Thx would probably not give the same recommendation for that.

http://www.thx.com/consumer/thx-technology/thx-reference-level/






10 subwoofers is freaking ridiculous ask christopher nolan or steven spielberg if they think its necessary to have 4 18 inch subwoofers in a fairly large house room to truly experience their movies.
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post #15 of 54 Old 03-16-2013, 12:14 AM
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4-8 subwoofers and how many cubic feet is a movie theater agan? And what drivers and watts rms are being used in conjuction with their max power handling and sensitivity? they probably dont have 8000 watts rms pumping out.

No matter how you put it its ridiculous having 10 subwoofers its utterly obserd. No one on these forums has a room big enough that needs 10 subwoofers 1-2 max.

Sure 10 subwoofers but you dont need them all theyre probably running at 10% full load so its just to say mine is bigger at that point 10 subwoofers isnt overpowering your mains if theyre only putting out 95 decibels accumulative the point is you could acheive the same sound with 1-2 subwoofers and that 10 subwoofers is unnecessary

10% load?

It's a bit more than that.
I can easily pin that FP Lab clone amp (and do), as per the LEDs in the video. That's not just me picking a number from the sky, the video proves that I'm there.
and that single amplifier of mine is rated at over 8000watts as-it-is.

My mains here are running closer to 105db (FYI).

I don't set the rules of physics, it takes what it takes.



Saying that 1 subwoofer can do this in the same way, is the most absurd thing I've read, in over a year.
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post #16 of 54 Old 03-16-2013, 12:24 AM - Thread Starter
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So what exactly is the point of your thread? You asked a question, people give their opinions and you try to shoot down what they say?

This is a great site with literally TONS on info from some pretty smart people in the industry. Try using the search option and do a little digging and you'll find all the answers you're looking for.

Im sorry when people ignore common sense it bothers me.
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post #17 of 54 Old 03-16-2013, 12:26 AM - Thread Starter
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Originally Posted by BassThatHz View Post

10% load?

It's a bit more than that.
I can easily pin that FP Lab clone amp (and do), as per the LEDs in the video. That's not just me picking a number from the sky, the video proves that I'm there.
and that single amplifier of mine is rated at over 8000watts as-it-is.

My mains here are running closer to 105db (FYI).

I don't set the rules of physics, it takes what it takes.



Saying that 1 subwoofer can do this in the same way, is the most absurd thing I've read, in over a year.

So in other words those go to 11 :-)
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post #18 of 54 Old 03-16-2013, 12:26 AM
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Im sorry when people ignore common sense it bothers me.

Cool, it bothers me when people can't do a simple search on a subject.

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post #19 of 54 Old 03-16-2013, 12:29 AM
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Single subs have more issues dealing with nulls and room modes. A simple search will tell you that.

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post #20 of 54 Old 03-16-2013, 12:34 AM
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Originally Posted by ComputerTech0903 View Post

That doesnt make sense. Dolby truehd is 5.1 you cant have trichannel base when the .1 stands for 1 channel there is no true tri channel mode.

Sure getting a crossover and spliting a 2 channel signal in to low mids and highs so your mains play the mids and high and a crossover for each channel splits it so you have one subwoofer for each channel is fine but thats not the same thing.

The .1 is dedicated to bass yes. But the other channels also have ULF bass too (say 15hz), which practically no (reasonably-cheap) full-range speaker can reproduce, so without subs on those channels as well, then you aren't getting the full spectrum of reproduction (as the director may have intended).

"Technically" it is a discrete channel and it can have 15hz in it, and thus could be considered a valid bass-channel that needs a subwoofer on it.

The only exception is if your main speakers go to say 10-15hz, which probably only the top 1% of systems do.
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post #21 of 54 Old 03-16-2013, 12:35 AM - Thread Starter
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Cool, it bothers me when people can't do a simple search on a subject.

When your speakers are louder than a hand drill of 98 decibels and you listen to it that loud then i suggest searching for titinitus treatment as i wear ear plugs at my work when i operate a machine thats a little over 90 decibels.
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Originally Posted by ComputerTech0903 View Post

And how confusing is it to have 8 subwoofers in a square around you. Remember subwoofer singnals are mono its not surround it would be confusing hearing a mono sound coming from 8 directions its like if you heard the drip of water coming from 8 directions at once its confusing.

Not confusing at all. Yes, the LFE channel is mono, but low frequencies covered by the subs are omnidirectional. You will not be able to pinpoint where the sounds are coming from like you would the sounds coming from your satellite speakers. With the assumption that they are properly integrated into your system.
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...and b 1-2 high quality subs with enough power will have such low distortion and enough power when properly configured you dont need any more "headroom" ...

So what is it? You don't need "more-than-1-really-good-subwoofer" or is it "b 1-2 high quality subs with enough power will have such low distortion and enough power when properly configured you dont need any more "headroom""? So one sub or two? First you state you only need one then you go on to say one or two. Why not two or three or three or four? At what number do you draw the line as what everyones' needs are? A sub that satisfies your needs may not satisfy the next guy. Can you think of a single sub with enough power to properly pressurize a 30K+ ft3 room and provides a flat response down to 10Hz at all seating areas? Mind you there are many movies that dip below 10Hz and more will be on the way.
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...remember headroom actually stands for something and thats distortion and power

Since when did headroom stand for distortion? Having headroom helps to mitigate distortion.
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In 2 channel music you dont have 4 speakers representing each channel surrounding you for a "flatter response" so why should a mono channel subwoofer be any different.

It should be different because low frequencies are influenced by your room much more so than the mid and upper frequencies. Mid and upper frequencies are directional.You can close your eyes and point to where those sounds are coming from. You would not be able to point to the source of low frequencies coming from subs that have been properly integrated with your eyes closed.
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Its ridiculous no matter how you put it.

I think going to the movies is ridiculous no matter how you see it. Does that make it true? Not according to the millions of people who go each week. Just because I don't see the merit in it doesn't mean it has no value or benefit. Just keep in mind audio is a mostly subjective pastime and try and keep an open mind. What's good for the goose may not be good for the gander.
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So its not ok for 2 channel music to have 8 speakers surrounding you for 2 channel audio for a flatter response but it is ok to have a one channel mono subwoofer signal split to 8 subwoofers surrounding you all around the room?

Multiple satellite speakers will not give you a flatter response. At least not an appreciable difference. See my explanations above regarding room interactions differences between subs and satellite speakers.
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Once again, what is the whole point of your thread besides wasting people's time reading it?

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post #24 of 54 Old 03-16-2013, 12:54 AM
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Originally Posted by ComputerTech0903 View Post

When your speakers are louder than a hand drill of 98 decibels and you listen to it that loud then i suggest searching for titinitus treatment as i wear ear plugs at my work when i operate a machine thats a little over 90 decibels.

Thanks for the warning mom rolleyes.gif

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post #25 of 54 Old 03-16-2013, 01:03 AM
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Originally Posted by ComputerTech0903 View Post

So in other words those go to 11 :-)

My system can do 190db @ -20hz. It reverses time and goes back to the future with 1.21 jiggowatts.




Quick, nobody tell the op that I have more than 16 subwoofers (or he'll think I'm nutz). Oops too late. hehe
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post #26 of 54 Old 03-16-2013, 01:35 AM
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Here's a whitepaper about the response-smoothing benefits of multiple subs (from a sub manufacturer, yes, but multi-sub measurements from many independent enthusiasts also support the findings in the paper):
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf
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Originally Posted by ComputerTech0903 View Post

Ughh thx level is 85 decibels with 20 decibel peaks not 100 decibels and 20 decibels for peaks.

Here's a thread about reference level. As you said, it is 85db with +20db peaks for the speakers, except for the sub (LFE channel), which is +30db (115db):
http://www.avsforum.com/t/1252556/what-is-reference-level

Note that "reference level" is just a specific volume level, which requires enough headroom to handle the peaks (whose maximum level is determined by the recording format, e.g. Dolby Digital, or DTS). But of course, people actually listen at levels that differ from reference level. Most people watch TV or movies well below reference level. But it is fun to turn it up to reference level, or higher, sometimes, and you can do so without damaging your hearing so long as you limit the exposure time appropriately for the level that you choose.

Building a system that can play at reference level is non-trivial. It is not easy to hit 115db at 20Hz at your listening position, for instance. It takes multiple subs, which is an additional reason, beyond the response smoothing reasons that I already mentioned, why someone might want multiple subs. Very few home systems can hit reference level, and most of the ones that can were probably built with a specific focus on being able to do so. I think we got on this particular tangent because you were skeptical that having subwoofers that can play to 120db has any value. For many people, it probably doesn't. But you can make full use of subwoofers that can play 120db or more at your listening position without immediately damaging your hearing. For a lot of us, achieving that kind of audio performance is a hobby, and experiencing it is a thrill.

You don't have to participate in the hobby, but I assume that you came here to learn about this stuff. You asked us why people have multiple subs, and why anyone wants to run their bass "hot". Several people including me have given you reasons why. Unless you are BassThatHz's neighbor*, I don't think there's any reason to be mad. Let's keep this friendly -- we'll have a better discussion that way.

-Max
* I know, BassThatHz, that you are taking extraordinary measures to create a sound cocoon to maximize performance and minimize neighbor disturbance -- I was just kidding about that neighbor thing.
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post #27 of 54 Old 03-16-2013, 03:21 AM
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"Ughh thx level is 85 decibels with 20 decibel peaks not 100 decibels and 20 decibels for peaks."

thx reference level is 105db peak at the listening position for each channel (the "5" in 5.1).
the reference level is 115db peak at the listening position for the lfe channel (the ".1" in 5.1).

in addition to this, re-routing the bass from the main channels to the subwoofer channel below the crossover point adds 5 additional channels of 105db peak content to the 115db of the lfe. if these sources are "coherent" (aka, all the same), a total of 119.6 db is required.

in order to produce 119.6db peaks at the listening position across the entire bass region typically requires more than 1 subwoofer.



and the voltage that goes to your "sub" that should be calibrated for reference level:



source: Sound for Film and Television By Tomlinson Holman (the TH in THX).

interestingly, i could not find the original source for the "reference level" specification.

Listen. It's All Good.
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post #28 of 54 Old 03-16-2013, 04:15 AM
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My recommendation would be to read (a lot) more and post less. There are things going on with audio reproduction that you simply haven't grokked yet, and if and when you do you're going to feel rather silly about some of what you have said here. This particularly applies to your remarks on common sense, which is currently failing you in this regard.

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post #29 of 54 Old 03-16-2013, 05:04 AM
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Originally Posted by JD in NJ View Post

My recommendation would be to read (a lot) more and post less. There are things going on with audio reproduction that you simply haven't grokked yet, and if and when you do you're going to feel rather silly about some of what you have said here. This particularly applies to your remarks on common sense, which is currently failing you in this regard.

"Stranger in a strange land"....it's been a few years since I've re-read that....might do it again as result of this thread....


OP, read these 4 links:
Then look at my thread http://www.avsforum.com/t/1446659/multi-sub-help-adding-diy-18-and-12-sub-to-4-x-15-ib-line-array-possible-diy-triangle-18-sub-24-sides-x-34-face-x-32-tall-5-5-cu-ft
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post #30 of 54 Old 03-16-2013, 05:53 AM
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Quote:
Originally Posted by LTD02 View Post

in addition to this, re-routing the bass from the main channels to the subwoofer channel below the crossover point adds 5 additional channels of 105db peak content to the 115db of the lfe. if these sources are "coherent" (aka, all the same), a total of 119.6 db is required.

LTD, can you outline or link to the math for that? Audioholics has stated here you need 123 dB SPL if you redirect from all the other speakers.

As for reading material, I think I'll just go read "Flatland".
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