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are 3db important?


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stevdart 
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Joined: January 24, 2004
Location: Pennsylvania, United States
Posted: March 04, 2006 at 5:00 PM / IP Logged  

You brought up some great points in your post, Jeff.  I'm stumbling, though, on your initial +3 db increase calculation:

wrote:
3260/2=1630watts per sub
87db+3db(for second sub)=90db at 1watt at 1 meter
90db+3=93@2watt
93+3=96@4
96+3=99@8
99+3=102@16
105@32
108@64
111@128
114@256
117@512
120@1024
123DB@2048watts@1 meter
Now where did our extra 27 decibles come from?

I was trying to get that initial +3 db in clear focus with DYohn's explanatory help above.  That second sub also needs one watt of input to give it its 87 db output rating.  So, with two subs you are starting out with 2 watts of power to achieve 90 db.  Each sub is powered by one watt, and since the power has doubled the increase is +3 db.  The addition of the second sub doesn't add another 3 db in and of itself......unless there was the same power applied to it as the first sub.

Right? 

Your build gain was actually more than 27 db's.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
prophesybh 
Copper - Posts: 78
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Posted: March 04, 2006 at 5:01 PM / IP Logged  
so in the long run is one sub just as good as two.  Since The db increase isn't that much.  for example,(an imaginary setup) if I got a 200 watt sub being pushed by a 200 watt amp, them added another 200 watt sub and another 200 watt amp, my db increase would be 3 roughly.  Am I correct or even on the right track.  Because I think if thats the case alot of people could save a lot of money in the end.
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t-roy81 
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Posted: March 04, 2006 at 6:00 PM / IP Logged  
from what ive learned, id say thats right, right up until you dont have one sub that can take the power, thats when you need to get two subs. then more and more, because if that speaker can only handle 400 then you can only get THAT one decible gain, if you have another speaker you have those decible gains also
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stevdart 
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Posted: March 04, 2006 at 6:49 PM / IP Logged  
It's amazing that the first additional 1 watt adds just as much to the total decibel count as that last 2,000 watts at the end (if you're going that far with the build).
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
tcss 
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Posted: March 04, 2006 at 6:54 PM / IP Logged  
Uh no, if he went from 200 watts to 400 watts on one sub it would increase volume 3 db.
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stevdart 
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Posted: March 04, 2006 at 7:28 PM / IP Logged  

All of the above are correct.

are 3db  important? - Page 3 -- posted image.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
prophesybh 
Copper - Posts: 78
Copper spacespace
Joined: July 04, 2005
Location: United States
Posted: March 04, 2006 at 7:37 PM / IP Logged  
so in a sense it's kinda a waste of money to get more than one sub unless your trying to use up the excess watts from your amp, cause 3db can be heard but not to the sense that it makes a big difference.  Is this right or am I stupid (lmao)
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jeffchilcott 
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Posted: March 04, 2006 at 9:24 PM / IP Logged  
stevdart wrote:

You brought up some great points in your post, Jeff.  I'm stumbling, though, on your initial +3 db increase calculation:

wrote:
3260/2=1630watts per sub
87db+3db(for second sub)=90db at 1watt at 1 meter
90db+3=93@2watt
93+3=96@4
96+3=99@8
99+3=102@16
105@32
108@64
111@128
114@256
117@512
120@1024
123DB@2048watts@1 meter
Now where did our extra 27 decibles come from?

I was trying to get that initial +3 db in clear focus with DYohn's explanatory help above.  That second sub also needs one watt of input to give it its 87 db output rating.  So, with two subs you are starting out with 2 watts of power to achieve 90 db.  Each sub is powered by one watt, and since the power has doubled the increase is +3 db.  The addition of the second sub doesn't add another 3 db in and of itself......unless there was the same power applied to it as the first sub.

Right? 

Your build gain was actually more than 27 db's.

I figured in that the second sub also needed the 1 watt of power to achieve the 87db...thats why I stoped figuring at slightly over 2000 watts, we were running 3260watts...1620.....87plus sub then up to 1620    either way it was quite inaccurate   haha
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gbear14275 
Member - Posts: 22
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Joined: May 09, 2005
Posted: March 04, 2006 at 11:01 PM / IP Logged  
stevdart wrote:

wrote:
3db according to what i heard is the limit of perception by the human ear.

Nope.  Read what was said in posts above.  1 db is the perceptive level...that's what signiifies the measurement of the decibel.  Otherwise, why make it 3 decibels?  What, then, would a decibel signify?  1/3 of the limit of perception by the human ear?

The only thing i may say in response to this is many times levels of measurement aren't made to conform to human perception levels.  example.  can you tell the difference between a room that is 70 degrees f and 71 degrees f?  Or a weight that weighs 45lbs and 46lbs. 

looking up the history of a decibel on google I found a few different sites but all of them say that the decibel came from the bel which was a measurement alexander graham bell used to signify the percieved doubling of sound levels.  The decibel was defined as 1/10th of this.

here is the link to the wikipedia site on decibels

http://en.wikipedia.org/wiki/Decibel

one thing i figured i'd point out is:

"A 3 dB increase in the level of continuous noise doubles the sound power, however experimentation has determined that the frequency response of the human ear results in a perceived doubling of loudness with every 10 dB increase; a 5 dB increase is a readily noticeable change, while a 3 dB increase is barely noticeable to most people."

So some people may be able to hear a 1db change just like some people can tell a 1 degree F temperature difference or a 1lb weight difference but for most people that is the smallest perceptible change in volume.

gbear14275 
Member - Posts: 22
Member spacespace
Joined: May 09, 2005
Posted: March 04, 2006 at 11:07 PM / IP Logged  
t-roy81 wrote:

what is the point where yours ears pop?, ive heard of it, and my car seems to come close but i was just wondering. is there one?

Sound levels above 85 dB are considered harmful, while 120 dB is unsafe and 150 dB causes physical damage to the human body. Windows break at about 163 dB. Jet airplanes cause A-weighted levels of about 133 dB at 33 m, or 100 dB at 170 m. Eardrums rupture at 190 dB to 198 dB. Shock waves and sonic booms cause levels of about 200 dB at 330 m. Sound levels of around 200 dB can cause death to humans and are generated near bomb explosions (e.g., 23 kg of TNT detonated 3 m away). The space shuttle generates levels of around 215 dB (or an A-weighted level of about 175 dB at a distance of 17 m). Even louder are nuclear bombs, earthquakes, tornadoes, hurricanes and volcanoes, all capable of exceeding 240 dB. A more extensive list can be found at makeitlouder.com.

Dyohn it sounds like you know your stuff so I wasn't trying to say differently than you posted just found that as I was reading through the stuff.  Although...wikipedia is a user donated dictionary so you can't take the information on every topic in there as gospel.

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