Help choosing sub

[talnlnky]

Originally Posted by Alien Mantis

You contradict what many manufacturers are recommending to consumers.

I read plenty of information from the likes of Alpine, JL, Pioneer, etc... that claim you are just flat out WRONG.

You CAN underpower a sub.
Whether or not it will damage it... I don't know.

A sub is designed for a certain "power-range".
If you give it too much power, it can smoke it.
If you give it too little power, you won't have any performance/response out of it.
High power subs NEED power to push them, and keep them tight, especially at higher volumes.
If we could use a 50watt amp on our pair of Alpine Type-X 12" subs, EVERYONE would be doing it!
Who wants to spend $400 on a 1,500watt RMS amp if I can push my sub setup with 50watts ?!?!?

Subs like the JL W7 and Alpine Type-X REQUIRE lots of power to push them, and keep the response clean and tight, especially at higher volume levels. Nobody buys a JL W7 to play SOFTLY.
People spend big bucks on this stuff because they want people to hear them coming down the street.
PERIOD.

My Alpine Type-R 10" sub has a recommended power range of 200-500watts RMS. And 200 watts would be the bare MINIMUM. It probably sounds pretty weak with only 200watts trying to push it.
( and most likely, not as tight sounding, either )

Putting 50watts on a JL W7 probably wouldn't even make the cone move.

Subs that have high efficiency ratings can play louder with LESS power, but they still need SOME power.
Subs, ( especially GOOD subs ), have a higher power rating, and a lower efficiency rating because they are made for high power.
They NEED high power.

SQcomp is right though, all systems must have all the gains set correctly.
You cannot use an amp gain knob as a "volume" knob.
And all your components must MATCH each other.
Don't buy a 2,000watt RMS sub, and put a 400watt amp on it.
Don't buy a 500watt RMS max sub, and hook it to a 1,500 watt RMS amp.
You are just wasting money.

You CAN run a larger amp on a weaker sub, you just need to turn the gain down on the amp.
The question is, WHY would you do this?

My sub is rated at 500watts RMS max, and I have it hooked to an amp that puts out 400watts RMS.
My gain is set around the 10 o`clock position, my preamp outs are around 2.2v.
My sub sounds very nice, and my sub and amp run cool.
My amp barely gets warm, even after blasting it for an hour straight.
( my sub amp has a 2ohm load on it, at 4ohm load... it never even got warm. )

Maybe I am totally wrong, but I read articles and specs, and I see people with opinions that contradict what I read sometimes.
I know you guys have lots of experience, and I am not challenging your experience. I am just confused by what you just said about a 10 watt amp powering a 12" subwoofer.

I NEVER heard of anything like that.

Don't blindly trust the information coming from the person that has something to gain from you.

Is there such thing as too small of an amp? No
Do I recommend buying a bigger amp than you need? Kinda, for people who know audio I do, for people who can't set gains & eq levels properly I don't.
Will clipping hurt a sub? No, but the extra heat that it causes could toast your coil if you have too much total power going to the sub... furthermore, for a fully clipped signal (square signal) you'll have 20% less voice coil cooling due to the decrease in cone movement... so if you had a 1000w sub... now it can only take 800watts.... if you had a 800watt amp and are now clipping it... you could be pushing close to 1600rms. if you had a 300watt amp... you are still below the 800rms mark even with a fully clipped signal.

Manufacturers say things for two reasons...
1) to make money
2) to teach the ignorant, without getting technical - therefore, a lot of what they say isn't exactly true, but for the masses, it'll generally steer them in the right direction... however, the whole issue with amp size/clipping... they're in it for money. Clipping is a problem that stems out of GREED (for more spl) or ignorance (in not knowing how to set gains & eq levels). Neither will be fixed or even bandaged with simply buying a larger amp.. in fact, your chances of cooking your sub if you have a larger amp are significantly higher, because you won't have to clip as much to reach the thermal limits of the sub... Clipping is a nasty sounding distortion too... its rare that people have a 100% clipped signal.... but its also not uncommon for people to have a clippless signal.




Oh yeah... I think I saw something about size of cone being better or worse depending on the music you listen to.... cone size has NO EFFECT on how tight or sloppy a sub sounds. That is all determined by the Le of the voice coil, the design of the box, and the group delay & frequency response peaks. 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.

[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.

[Alien Mantis]

Originally Posted by talnlnky

Don't blindly trust the information coming from the person that has something to gain from you.

Manufacturers say things for two reasons...
1) to make money
2) to teach the ignorant, without getting technical - therefore, a lot of what they say isn't exactly true, but for the masses, it'll generally steer them in the right direction.

I agree.

But the manufacturers recommendations are a good reference.
Their information is not incorrect, it just might be somewhat incomplete.
Alpine gives you good information on how to treat their subs for maximum performance.
Remember, these companies want you to be SATISFIED with their products.
They want your install to be successful.
They do NOT want you to burn up your new subwoofer in 3 days, and send it back to them for a FREE warranty replacement.
So they are going to do their best to steer you in the right direction.

If you like their products, you will buy them again, and you will tell your friends to try them.

If you have bad experiences with their products, you will most likely NOT ever buy their products again, and "word-of-mouth" negative publicity can kill their sales numbers.

We all have certain brands we stay away from. And we all have certain brands we like to use.

For me, it is always "bang for the buck", how well the products are engineered and assembled, and how good is their customer support after the sale.
After that, comes product appearance.

If I am satisfied in ALL those areas.... they got my money!

Anyone can pay $600 and get a really nice subwoofer.
But can you get a really nice subwoofer for $100?

THAT is why I am in love with the Alpine Type-R.