Help choosing sub

[Alien Mantis]

Originally Posted by talnlnky

8's can play as low as 15's, tho they usually aren't designed too, 15's can be just as tight as 8's... tho people usually don't design their installs to sound that way.

You are correct, but the reason people don't use 8's for 25hz bass is because at that frequency, you need eight 8's to be LOUD.
It's WAY cheaper and easier to just run a pair of 12's instead.

And the same goes for 15's.
If you want tight bass around 80hz, why run a giant 15" sub, stuff it in a small sealed box, and put a big power-sucking amp on it just to make it play tight?
Instead, run a pair of cheap 8's or 10's.
Less space, less power needed.

You are totally correct, you CAN get anything to play anything.
It's just not the practical thing to do.
( but when has "car audio" ever been about "practical" ? )

[talnlnky]

Originally Posted by Alien Mantis

You are correct, but the reason people don't use 8's for 25hz bass is because at that frequency, you need eight 8's to be LOUD.
It's WAY cheaper and easier to just run a pair of 12's instead.

And the same goes for 15's.
If you want tight bass around 80hz, why run a giant 15" sub, stuff it in a small sealed box, and put a big power-sucking amp on it just to make it play tight?
Instead, run a pair of cheap 8's or 10's.
Less space, less power needed.

You are totally correct, you CAN get anything to play anything.
It's just not the practical thing to do.
( but when has "car audio" ever been about "practical" ? )

agreed, there is always a tradeoff.... or even many tradeoffs. If you do an install with eight 8's... your tradeoff is going to be price... the benefit will be efficiency. So, what you lose in money spent on subs... you'll at least partially make up on the cost of a sub amp (if you just want a specific dB goal) and also the lack of having to upgrade the big 3, alternator, or battery(s). Also, smaller cones proportionally require smaller box sizes (so you can fit more in the same sized box).

explanation: take an 84dB @ 1w/1m 8" sub... compare that to the 15" which will play 88dB 1w/1m... if you give each sub 1watt of power, there will be a +4dB difference in favor of the 15" sub.

considering +3dB change in output for every doubling in cone area you get the following...

1 = 84dB
2= 87dB
4 = 90dB
8 = 93dB

all of a sudden your +4 dB advantage for the 15" turned into a -5dB difference/disadvantage.

now, I was just throwing out numbers, I wasn't taking real specs from real subs... but 88dB for a 15" is reasonable... and so is 84 for an 8". You get the picture.

I had a friend who did an install with eight $50 8" subs and it was actually one of the loudest street beater vehicles I've heard... and he only had 150watts of power. Funny thing is... he could've safely used upwards of 1,000watts... tho... realistically he would've only gained about 5-6dB.... theoretically he would've gained about 7.5-8dB


EDIT: I've always been about best bang for the buck....take my gear list for example... I have something like $4k worth in products... but only one or two things were bought new, and at least one item wasn't functional when I bought it (had to do a lil solding work). For that, I was rewarded with $4k worth in gear for a quarter of the cost... all legit sales, nothing hot or anything. Not everybody is all about best bang for the buck tho... so I preach more than just my preferences.

Like alluded to above, some people care more about cargo area, for them... going with dual or tri 8's might be a better option than going with a single 12". Or if they really wanted to experiment... there are a handful of 5.25/6.5/7" speakers that can actually be considered subs that require insanely small boxes, even when ported.


EDIT: on another note... I kinda disagree with about a company not wanting you to blow up your gear. Of course they don't want you doing it in the first three days.... or maybe not even in the first 6 months... but a year or two down the road... Oh yeah... Many people will go back and buy that same gear if they liked it the first time... even if it did die an early death.... Look at all the people who continued to drive american cars despite decades of horrible reliability. Granted ford is now getting better, but I still see chevy's gmc's, and pontiacs everywhere I go.

John deere almost drove themselves out of business because there 2cylinder tractors were too reliable, nobody ever had to replace parts. They eventually figured out that if they created 6cylinder tractors that people would buy them, despite not being as reliable simply because they would be more powerful... and the company would then get repeat customers.

Audio companies are the same way... the tricks is finding the proper balance.. some of the companies that say their subs can handle 1000w are flat out lying... sure the coil won't die today... but a year later it will. for every 10degrees farenheit you lower the temperature of a circuit (voice coils are no different)... you double its life. Every speaker will die eventually due to a burnt coil if given enough time... the time will be dependent on how much power that coil sees. I've given 800watts to a 10watt speaker before. It lasted 8-10seconds. The mathing speaker to it was over 10years old... and still kicking strong... course it had only been seeing 5-10watts of power, but give it another 10-20years and it would've died too.