Twice as loud ? Lets talk dB's

9 years 9 months ago #1 by DiscussBot

Decibels, dB, are a measure of loudness. Unlike other measurements, decibels are logarithmic in scale not linear.

Speed is linear, 40km/h is twice as fast 20km/h. Time is linear, 60 seconds is twice as long as 30 seconds.
Decibels arent, 80dB isnt twice as loud as 40dB. 80dB is twice as loud as 77dB !

This is how "decibels" interprets into "loudness":

+1db is 1.25x louder
+3db is 2x louder
+ 20db is 100x louder !

Click here for an excellent Wikipedia article explaining why this is so.

So to get twice as loud as your buddy you only need to gain 3dB's, but how ? Easy, you have a few options..
1. Double the power into your existing subs. Only have 500WRMS ? Get another 500WRMS !
2. Double the cone area and power. Just adding a second sub doesnt work. Why ? Because you half the power going into the first one !
3. Tune the enclosure using our nifty "SPL tuning guide"

If you have a quality amp that can handle low impedences, you can cheat a bit. Have a duel 2ohm woofer wired in series for 4ohm and 1ohm stable amp ? Parallel the coils for a 1ohm load !
Same deal with adding an extra sub, or more... load down the amp if possible and safe and voila ! More power and more cone area.

So what have we learnt ? dB's are all 2's and 3's !
2x Loud = +3dB.
2x Power = +3dB.
2x Cone = +3dB (with 2x power)
0.5x ohms = 2x Power (half the ohms load = 2x the power !)

6 years 8 months ago #2 by speakerrepair
so i built a sub thats got a quad 2ohm coil that gives me 0.5ohm bridged in parralel. if i build another and then series them i get 1 ohm . will this help me increase my dbs.
6 years 8 months ago #3 by Tezzating
Well it depends. If your amp will give you power at 0.5ohm, then introducing a second sub will halve the power both subs get and the amp will make less power at 1ohm than it will at 0.5ohm, so you will probably not see a gain.

If the amp wont give you power at 0.5ohm (goes into protection), then the 2 subs @ 1ohm will be louder as the loads lower and cone area bigger than you get with just the one.

It comes down to your amp really.

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