Questions on subwoofer specs and how they correlate

[Kross6622 10+ year member]

First off i have a very basic understanding of specs listed by manufactures. I'm referring to things like RE, BL, Fs, Xmax etc...

Now im always thinking. One of my friends was thinking about running a multiple sub setup over his current setup. Now i know the general rules in terms of more cone area is + and more motor strength are a +.

Im going to try and explain what im thinking.

2 -18" subs = ~ 500in^3

4 -12" subs = ~ 450in^3

In this case the 2 18's will have more cone area.

Now when it comes to motor strength can you add up the motor strength, or is there a way to compare how 2 motors to 1.

Example (BL^/Re)

1 Big motor = 265

3 smaller motors = 70(each) = 210

from a statistical standpoint, is this possible?

Now i understand the amount of power, suspension, cooling, efficiency are all other factors that can play a big role. But from a broad standpoint is this acceptable. why or why not?

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[T3mpest 10+ year member]

It depends on the setup. Performance will be close, 18's are cheaper, so that's probably what i would go with. The main advantage to the 12's is that since you have alot more coil, you'll strain the subs less thermally given equal input power.

 

[Kross6622 10+ year member]

It depends on the setup. Performance will be close, 18's are cheaper, so that's probably what i would go with. The main advantage to the 12's is that since you have alot more coil, you'll strain the subs less thermally given equal input power.

Yea, i understand that. But is it possible to compare motor strengths, and is it a legit way to compare, or is there to many factors.

 

[THATpurpleKUSH 5,000+ posts]

AFAIK there are too many factors to get a legit comparo of motor strengths. One sub could have a weaker motor with a higher xmax and more cone area and be just as loud as one with a smaller xmax and cone area with a stronger motor. The only way I know of comparing motors is by looking at the tesla meters, the higher the stronger. I know mms and cms are important somehow but not sure how to factor those in. Specs on paper only get you so far imo. The numbers that you see printed on paper are often an average of various readings taken from the production line, according an electrical engineer I know who builds boxes and has been in the industry for over 15 years.

 

[Kross6622 10+ year member]

AFAIK there are too many factors to get a legit comparo of motor strengths. One sub could have a weaker motor with a higher xmax and more cone area and be just as loud as one with a smaller xmax and cone area with a stronger motor. The only way I know of comparing motors is by looking at the tesla meters, the higher the stronger. I know mms and cms are important somehow but not sure how to factor those in. Specs on paper only get you so far imo. The numbers that you see printed on paper are often an average of various readings taken from the production line, according an electrical engineer I know who builds boxes and has been in the industry for over 15 years.

That was exactly my thought too. I know what your saying and like you said one with less cone area and less xmax but a stronger motor can be as loud, im wondering if there is a way to interpret these numbers. As well as how you would interpret 2 motors to 1.

I know there is not going to be a magical way to do it. But a rough comparison of 2 subwoofer t/s specs.

 

[T3mpest 10+ year member]

yes, it's called winisd. Modelling programs can do it much quicker and allow you to manipulate your box sizes, port sizes, etc and see how it all correlates. If the T/S are accurate, modelling programs work very well. Even if you dont' include cabin gain, since both subs and boxes would be going into the same vehicle, it's a fair fight. WINISD alpha is free and does what you need for basic modeling, plus it's very easy to use.

Anyway Xmax is mostly important in sealed alignments, ported usually higher BL wins out. This is because running out of excurison in a sealed box much easier do than ina ported box. This is because the port will reduce excursion around tuning because the port and sub are 180 degrees out of phase. A high BL allows the sub to move further near tuning and be more effecient around the tuning frequency as a result.

Anyway, that's the easiest and most reliable way to compare different setups if you have T/S available.