advantages of 2 subs over 1?

[whiterps13]

ok, i am now in the market for a new subwoofer setup due to blowing my last sub to pieces.. what i am contemplating is weather to get 2 subs or 1. i am looking at a 1500 watt hifonics amp powering an orian 10, or a similar 1500 watt amp powering 2 750 watt subs. what are the advantages to running 2 subs over one? the weight savings seems better with one, and also it takes up less space. why do the majority of people run two subs?

[ayjay]

well the reason why most people run two subs is because it is simply louder with the same amount of power... when you two subs are used sensitivity of that setup is higher... so for example, if you were to run a single orion sub with 1500W that would be frickin loud, but if you were to run two orion subs with that 1500W that would be even louder.

personally though i'd rather get a single 12" (not a 10") cuz it's just really cool to pound a single sub so loud... plus it's much better if you are going to compete because then you'd be put in the lowest class, if you were to get two subs you'd be put in a higher category...

one thing is i'm not too sure how having multiple subs affects sound quality, for better or for worse i dont know..

[whiterps13]

well i was thinking about a 12", but when i had my 10" i loved the hard-hitting bass notes that only a 10" can give you. maybe i will consider a 12" though, because it can hit those lower notes. i hate decisions.

[Rex]

Wow, we could be starting quite the debate here.

How can 2 speakers powered (effectively) with the same power be louder, than a single speaker?

It's an assumed standard that it takes a doubling of power to achieve a 3db gain, so if I double the speakers (assuming maintaining the same ohm load) wouldn't the amount of power seen by each speaker be half, therefore creating a 3 db drop?

[elwesso]

I lke single better because it frees up trunk space, whereas most 2 sub boxes take up the entire trunk!!

[Repo Man]

My feeling on it is this; run two subs and be able to run more power. You will move more air, given the subs are all equal in size, be louder and may or may not sound better. Set it up so that you can remove that box when you need the space or when you are autocrossing/track days.

I had two SPL 15's in the trunk of my Turbo Regal and it was loud as hell. Louder than the three Eclipse Aluminum 12's in Simmsled's car. Of course, he built both systems.

[audtatious]

Assuming equal power, 2 subs will give you +3db over a single sub configuration. If the 2 subs are sharing the same enclosure and are close together, you could get up to another +3db due to coupling effects.

Just be aware that the sensitivity of two different subs will affect sound levels. A sub with 87db sensitivity will not be as loud as a sub with 90db sensitivity assuming the same power and same environment. Example: you have a sub with 90db sensitivity using 800w and another sub with 87db sensitivity using 1600w.....Both will have the same SPL. If you run 1600w to the sub with 90db sensitivity, it will have +3db more SPL than the other sub.

[ayjay]

coo, thanks audatious, thought rex might have had a point, but he didn't (no offense rex, you know your ****) :pface but i think general rule of thumb is +3db for either double the power or double the cone area... sensitivity increases when the subs are within the same enclosure, at least that's what WinISD says. take two 13" Focal Polykevs for example... a single one is 91db sensitive, but the two in combination give a 97db sensitivity... although that's not entirely accurate, you get the just of it, and shows that two subs will be louder than single sub with same power.

learn new **** everyday

[Rex]

I could be completely off in left field, but I find it hard to believe that if I have 1 amp driving the same ohm load pushing 2 woofers, instead of 1, it would be louder???

I have no specific knowledge, but if most sensitivity ratings are 1 watt at 1 meter, then how can 500 watts split between 2 speakers be louder than 500 watts on 1 speaker??

Not necessarily disagreeing (sic), just trying to understand.

[Looneybomber]

Get one 12". Less space, less weight, less money. Get one that will handle plenty of power too. Hell screw it, get 4, 15" fosgate Stage2 powers!. Also get 4 1500bd amps. Wire each sub in parallel and each amp runs at 1ohm

[diamond]

+3 is the rule

[InstantRice]

+3 every time you double cone area. double the power is a little less than three but if your just doing some math in the head just round it off...to 3

[whiterps13]

Get one 12". Less space, less weight, less money. Get one that will handle plenty of power too. Hell screw it, get 4, 15" fosgate Stage2 powers!. Also get 4 1500bd amps. Wire each sub in parallel and each amp runs at 1ohm

good idea

[audtatious]

+3 every time you double cone area. double the power is a little less than three but if your just doing some math in the head just round it off...to 3

correct. Double the cone area with the same amount of power or double the power with the same amount of cone area for +3db.

Now, "perceived twice as loud" is something like 8-10db, correct?

[Looneybomber]

10db

[Simmsled]

Okay...

Each time you double cone area, 3db.Each time you double power, 3db.Perceived twice as loud is 10db.

BUT

In a car audio environment, you can have 2 subs sound weaker than 1 (of the same brand/model) if you have an improper enclosure or if the subs are out of phase (positive and negative wires not connected properly).

But theres more...

Also, there is a thing called (cabin gain) which is basically car audio talk for corner loading. This means that by pointing the subwoofer or the subwoofer port to a corner or placing it close to the rear of the vehicle, you will have more output by about 3db typically. Cabin gain is why the system in your 4 door sedan does not sound as loud as the same system in a hatchback. To those people, mainly Q45 and J30 owners, that argue that your gas tank and rear seat absorb lots of sound and that if they werent there that it would all sound the same, I will say this... It is true that they block/absorb soundwaves. I feel sorry for you guys as there is no real great solution to sub bass in those cars. But... When you place a sub or sub port near something, it vibrates whatever is there. This is why people put subs in home theater systems in the corner instead of in the middle of the room. It uses the walls as sounding boards. In home theater systems it can be a gain of 10db!!! Dry wall makes a great passive radiator.

So in conclusion... all things being equal, the more power and the more subs you add, the louder it will be.And a tip of advice... dont let a monkey install your system. And if you do not consider yourself a monkey but still dont know much about installing systems, Im not trying to discourage you from trying. Just dont expect perfect results without doing some homework and gaining some experience first.

Good luck.

[whiterps13]

thanks simm, but i will install it myself. i know enough to hook up the wires correctly and build a correct size box.

[audtatious]

and there's more.... lol

Here's some terms and their related explanations:

1. Boundry Effects: Sub placement in respect to the resistive boundries of the vehicle can effect loading. Proper loading in a vehicle can yeild as much as a +6db increase in acoustic power. That is equivilent to 4 times the applied electrical power. The benefit is limited to frequencies where the distance from the acoustic center of the driver to the boundary is less than on tenth of a wavelength. Example of boundry effects: Fill a sink with 4" of water, drop a little ball in the middle and watch the waves spread out evenly. Drop the same ball near a corner and you will see the waves are of a greater amplitude as they spread out.

2. Propagation vs. Modulation: In order to hear set frequencies, we must be able to sense the changes in air pressure. Since sound propagates (moves) at a fixed velocity, the distance between the source and the listener must be at least one wavelength. Propagation is the distance a soundwave travels during one period. As a reference, a 20hz soundwave requires 56.6ft and a 100hz soundwave requires 11.32 ft. Due to the small confines of a car, we are unable to hear the full tone of all low-end freguencies (now you know why vehicles with sub systems can have such a nice sound outside of the vehicle). In car audio environments, lower (longer) frequencies are perceived by uniformly modulating the air mass within the listening cavity. This ability depends upon a proportional relationship between the size and excursion capability of the driver(s) and the volume of air inside the vehicle (sufficient volume available for the sub). Ever been in a vehicle that sounds better with the windows cracked? Not enough interior volume for the subs.

3. Coupling: Modern recordings are normally mono below 100hz. When designing a sub system utilizing multiple drivers, efficiency can be maximized by positioning the drivers as close together as possible and by designing the enclosure such that pairs of drivers share a common cavity. In this configuration, efficiency may increase by as much as +3db and with the mono signal, will yield optimum wave propagation.

Properly setting up a system can be a time consuming process. Unfortunately, due to limitations in the environment, sub placement can be limited which will limit output. Hatchbacks are definately the better environment over sedans (my Probe rocked with the same setup I have now in my Maxima).

So, on top of proper enclosure design, properly building/bracing the enclosure, properly connecting the subs (phasing), level matching the components, frequency matching the components, setting gains, setting up the sound stage, and verifying ohms, you now get to play around with sub placement to achieve the greatest gains