Thread: single vs. multi subwoofers

advantages?

sure, cone area, more cone area means more bass...

rather than run multiples, I'd rather spend the same amount on a better sub....but then again, I'm not going for all out SPL....

what are you trying to achieve? SQ or SPL? or a combination of both?

purely SQ. I don't plan on ever seeing more than 200-300w RMS through the sub. so a larger cone at a given frequency yields a higher response... but at the cost of more power? or is the power consumption difference negligible?

If running a single driver, can you compensate a smaller cone with a boost in the low end using your EQ, or should your frequency response be resolved at the driver level first and then use EQ strictly for fine tuning?

Assuming in a perfect world all speakers are equal:

Lets say you have 100W

Doubling speaker or surface area with 100W = 3db gain
1 speaker + double the power (200W) = 3db gain

It takes 10db of spl gain for the human ear to perceive a "double loudness effect" and the human ear can usually only distinguish a minimum change of 1dB increments.

There is no right or wrong. It depends on how much space you want to give up or how much money you want to spend.

Originally Posted by GoHybrid

If running a single driver, can you compensate a smaller cone with a boost in the low end using your EQ, or should your frequency response be resolved at the driver level first and then use EQ strictly for fine tuning?

You cannot make a driver do something it wasn't designed to do. If you exceed the frequecy response of the driver you reach its mechanical limts and introduce distortion. So like you said:

frequency response be resolved at the driver level first and then use EQ strictly for fine tuning

well, unfortunately i am a complete enclosure novice. I think i've settled on a driver which calls for either a "Quasi 3rd Butterworth / Vented" tuned to 36Hz with 18 sq-in of vent area enclosure, or a sealed enclosure. What on earth is that? Is the seeming complexity of the former option worth the result? According to the response curves they give for each, the sealed enclosure begins to fall off somewhat sharply at 100Hz whereas the other falls off around 50Hz.

I'm still not clear on the whole multi/single driver thing. Are there destructive variances in the signal from one driver to the next? Is the output power split between the two drivers or is the draw doubled?

Thanks again to those who have responded. I'm learning alot by this.

There are not "destructive variances" as long as the drivers the same and have the same amount of air space.

Amplifier power is always split if the drivers are connected to the same channel on the amplifier.

Response graphs change inside a car. The "in car response" is completely different than what a normal response graph shows.

As far as box designs go, do a little googling and you will find endless pages describing the differences.

well i've been googling but struggling with the audio engineering nomenclature. I'll keep looking.

As far as response goes, i realize that the car environment has a profound effect, but doesn't the response even resemble the lab response curves, or is it so peaky that you really just have to RTA it to get everything in the neighborhood of normal again?

the vented box, if built properly will have a boost in the lower range closer to it's tuned to freq than the sealed box, which will be more flat, & not roll off until much higher than the vented box...

a port is a trade-off of gaining extra db, but loosing control below the tuned freq, & a steeper rolloff above it... it can be worth it if your goal is increased lower end output... which is why ported boxes are so popular...

average guy: bass+increased lower end output= goood

from a pure sq point of view, I personally prefer a sealed box in most situations... there will be no add'l boost in the lower end, but it will be tighter & more controlled... I like to be able to shoot for the real lowlows as much as the midlows, a ported box will give you a narrower band of higher output, & is pretty critical in needing the correct enclosure & port design if the final tune is off it can be less than great.....

if I choose a sealed enclosure, I choose speaker size dependant on the door speakers.. this is what I determine the subs on.....

if I have a 5 1/4 front door speaker, I would choose an 8" sub, maybe a 10" at the limit... the door speakers need to meld with the sub & if I went with a 15" sub my doors wouldn't play low enough to meet my upper range of the sub efficiently at all... this will cause a sloppy cross over point, & unecissary boosting in the xover range... you have to look at the rollof overlap & think about the xovers.... this is the primary mechanical tuning & the better you do efore the eq comes into the picture, the better...

a 6 1/2 is minimum to me for doors, & if there done nice & can provide a nice lower midrange, then the subs can be 10-12 no problem..., they'd have to hit nice & low to consider a 15 though.... I'd use a 15 with an 8" door speaker for sure.... the thing to think about is your first xover point to me when choosing the sub....

to me, if you really want the best bass, without any localization I say start with your front stage... the lower your front stage can play without rolling off, the lower the subs can roll off... if you use a good 8 & can get down below the 60's, then a ported box starts to look alot better, it'll be more efficent, & if the rolloff isn't going to cause any holes at the xover, then the only real tradeoff is having to have a steep rolloff below the tuned freq... where a sealed box can take advantage of a natural, much less steep lower rolloff, giving better reach into the really low freq. but not be as efficent...

in car natural bass boost is one thing, all vehicles gain will vary, but the xover freq is not really dependant on that, which is where the measured response comes into play... you can't really predict the natural cabin boost actual curve, but that's not important in selecting the right sub, sure it's a variable & a consideration, but not necissary in selecting a match in the doors to the subs..

hope this helps