3 subs vs 2 subs

[jtomsic 5,000+ posts]

what will be the difference because im adding another sub to my setup and im not really sure what i will gain, im sure it will be a little louder, but will i notice it with my ear?

Click to read more...

 

[iLL-Faded 10+ year member]

duh of course, its like asking if you would rather have 2 cars or 3?

 

[NaztyNate 10+ year member]

Technically you should pick up 3 dbs. But that is mathmatically and if it does pick up 3 dbs then it will sound 3 times louder I think since sound is a log function. But you will be able to notice a difference.

 

[audioholic 5,000+ posts]

It will not theoretically gain 3dbs, nor is 3dbs 3 times as loud (under any of the various definitions of 'twice as loud' etc). Doubling the amplifier power, or doubling the cone area will theoretically gain you 3db's, which is noticeable to the human ear.

To answer your question, it will be louder, noticeably. That's assuming you will also be adding the necessary power for a third driver.

 

[pscmj84 10+ year member]

It will not theoretically gain 3dbs, nor is 3dbs 3 times as loud (under any of the various definitions of 'twice as loud' etc). Doubling the amplifier power, or doubling the cone area will theoretically gain you 3db's, which is noticeable to the human ear.
To answer your question, it will be louder, noticeably. That's assuming you will also be adding the necessary power for a third driver.

Yes, you are right audioholic. I just want to add that for something to sound twice as loud to the humar ear an increase in 10 decibels is needed.

 

[audioholic 5,000+ posts]

Adding another driver adds 3 dB, but doubling power adds UP TO 3 dB because of power compression (decreased efficiency at higher excursion levels) it's usually less ...
So if the amount of power remains the same (1200 watts between 3 instead of 1200 watts between two), you should theoretically gain 3 dB, possibly a little more because the drivers should be more efficient (less excursion = less power compression). If you plan on increasing the power to give the same amount of power to each as you were giving the two, you'd gain up to 5 dB ...

I agree doubling power will yield UP TO the 3db's, depending on power compression. But we are talking theory here, ideal situations.

As for what would be twice as loud, that depends on what is considered 'twice as loud'. The only way we have to measure sound is by pressure. Who is to say 10db's is 'twice as loud'? Ive seen people make arguements that 5dbs is twice as loud, 6dbs, and yes 10dbs. Its not something tangible to measure and say twice as much, or half as much, as say physical size (measured in inches or mm's) or volume (as measured in cubic inches or liters). UYsually when this is brought up, the counter arguement is people with 'trained ears' have decided what's doubly loud... whatever. Until you do some of your own testing to see how much louder a 3db gains is (for instance), its all just a numbers game.

 

[jtomsic 5,000+ posts]

i will be pushing all 3 subs with the same amount of power and same amount of airspace(just finished my box). I made a sealed(didnt have enough trunk space for ported) box, but i use a prefab bandpass box right now, how much of a difference do you think i will notice with that? the box i built is constructed alot better, i stood and jumped on it and it didnt even make a noise or move. I sealed it up really well too. the prefab bandpass was from bestbuy and seemed pretty crappy quality but i didnt know what i know now.

 

[jtomsic 5,000+ posts]

bigger amp, for all three so that they get the same amount of power that the two were.

 

[Alpine CDA-9815 10+ year member]

As Jmac said, since you are going from a bandpass with two subs to a sealed box with three subs then I doubt it will be any louder... unless it was just some crappy prefab bandpass box. It will of course sound better/cleaner. Now if you made a new ported box for all three, then you should pick up some db's.

 

[jtomsic 5,000+ posts]

it is a crappy prefab from bestbuy

 

[denim 5,000+ posts]

if you want we could help you with the design of a new box

 

[jtomsic 5,000+ posts]

i finished the box already. just waiting for my dad to carpet it up cause he does carpet work, i used it as my graduation project, had my calculus teacher figure all my stuff out for me though because im not all that great at math. thanx for the offer though. i'd post pics but it says the pics from my digi cam are too big.

 

[jtomsic 5,000+ posts]

heres my box... not carpet and caulking wasnt dry in this pic

 

[joshpoints 10+ year member]

SPLdB is a measure of the logarithmic ratio between the acoutical pressure created and the acoustical pressure of the softest audible sound (2*10^-7 Pa) ...
Oh, and I couldn't remember the formula last night, so I just guessed 5 dB ... It's actually up to 4.761 dB ...

I doubt you'll respond to this but how did you learn this math info? Is there a book or site that you recomend that is good at explaining it?

 

[Acidburn 5,000+ posts]

physics book would tell you