I was wonderin if dual was a good brand or not. Im lookin at gettin new subs and i saw 2 12 duals at best buy and they went to expensive.

 

Check to see what they are made of paper, metal, or a type of plastic. This will detemine how long they will probably physicaly last, also check what power they can handle. Make sure that their peak is above or equal to the peak on your amp. Check out the specs on frequency response, OHM's, etc.. Just because something is inexpensive doesnt mean its bad, just like something expensive doesnt mean its good.

 

It's an-OK brand. I would put it with 'Lightning Audio' brand. From Best Buy, I'd recommend Rockford Fosgate, but If Dual fits your needs, go for it.

 

Also consider an amp that is rated slightly higher than the speaker. Most speakers are ruined from amp distortion and clipping than by overpowering.

It is better to overpower with a clean signal than underpower with distortion from the amp.

 

The cone material doesn't matter...
Paper cones will last as long as poly cones, ditto for aluminum cones.
Each has it's own advantages - more a design issue when it comes down to balancing stiffness vs. mass in the engineering stage, if not simply a cost or cosmetics decision.
But bottom line is [particularly for subwoofers, where cone breakup modes aren't even an issue], cone material doesn't contribute to performance or longetivity.

(I'm surprised to hear this one actualy... usually it's the old "foam vs rubber surround" debate, from people who can't conceive that foam technologies have advanced since the 1960's ...again, trust the loudspeaker design engineer - they made the right call for the application )

Also - I wouldn't run more than rated power to the sub...
Particularly since it was mentioned that clipping is a cause of damage.
Why?
Clipping causes damage because effectively it increases the power going to the speaker (unfortunately without increasing the amplitude of the signal!)... until it reaches a point where the actual power going to the speaker exceeds the thermal rating of the speaker.
OVERpowering a speaker is one of only TWO ways to "blow" a speaker.
So I wouldn't suggest ever purchasing more power than the speaker can handle - at least without a long discussion on understanding your listening habits.

(overexcursion damage is the other way to "blow" a speaker, btw... and it is also a powerhandling issue - although a mechanical one... a limit that's fully dependant on the design of your enclosure... you could technically bottom out your sub on an amount of power significantly less than what your speaker can thermally handle - in the right enclosure... er, wrong enclosure).

I also wouldn't sweat any particular brand name (although I wouldn't give Dual any special regard, personally).

Things that matter are more fundamentally tied to the engineer who designed the speaker... it's important to understand a little bit about the specs of the sub.

I start by figuring out if you [based on your listening habits] are more of a sealed box candidate, or a ported box candidate (and by that, I mean any of the flavors of sealed or ported boxes that exist- such as 4th order vs. 6th order bandpass boxes, transmission lines, dual-chamber tri-vent, passive radiator, etc. Let's not get into that...).

If you are more of a sealed box candidate ("I prioritize my sound quality as #1 to me"), then you need to find a sub that's ideal in a sealed box.
What makes a sub ideal in a sealed box is a low-medium amount of motor strength, so the sub isn't overdamped and dull sounding in a sealed box... and a low resonant frequency, so that it can naturally extend to low frequencies since there isn't a port to help artificially support the low frequencies.
If you want it to get loud, you'll need one with a good amount of excursion as well, since in a sealed box, loudness is simply a function of how much air the sub displaces as it strokes in and out - cone area times excursion.
Look for a sub with a Qts over 0.5 or so, and a Fs lower than 30hz by a good amount if possible. Look for a sub that's got 15mm or more of Xmax (and make sure that rating is one-way, not peak to peak... double it if p2p).

If you are more of a ported box candidate ("I want it to get as loud as possible!"), then you need to find a sub that's ideal in a ported box.
What makes a sub ideal in a ported box is a medium-high amount of motor strength, so that the cone can continue to be stroked in and out, even though it's battling the additional phase-aligned pressure forces of the port, which is adding to the pressures inside the box (phase aligned at most AT the tuning frequency of the box). You don't necessarily want a low resonant frequency (and naturally won't, since motor strength will inherently raise resonant frequency, unless you counter it by making the moving mass higher... which sacrifices efficiency), since you can design the ported box to extend the low frequency response of the sub. A higher resonant frequency will make the sub more efficient across most of the frequency spectrum, as will the higher motor strength - and the design of the ported box itself.
Look for a sub that's got a Qts below 0.45, and a resonant frequency that's ideally in the 30-35hz range.

Bear in mind the typical trade-offs in motor design involve how the windings are wound- trading off excursion capabilities for peak motor strength - you simply don't get both (save for new dual-gap technologies, which still involve those same compromises even still).

So, it's not important to ask "what about this [brand name here] brand?"
What you want to ask is "will this sub work, given my listening habits, and the space that I can afford to give up for a sub, and the power and impedance capabilities of the amplifier that will be running it?"

 

Duals are not any good. You can find a better set of subs some where else.

 

Also - I wouldn't run more than rated power to the sub...
Particularly since it was mentioned that clipping is a cause of damage.
Why?
Clipping causes damage because effectively it increases the power going to the speaker (unfortunately without increasing the amplitude of the signal!)... until it reaches a point where the actual power going to the speaker exceeds the thermal rating of the speaker.
OVERpowering a speaker is one of only TWO ways to "blow" a speaker.
So I wouldn't suggest ever purchasing more power than the speaker can handle - at least without a long discussion on understanding your listening habits.
Actually, an underpowered amp will clip on transients (fast attacks) and produce a flat-topped sine wave. The flat-top is basically sending DC current through the speaker, which will burn out the voice coil. With more power, the transient is faithfully reproduced, sending less current. Go for the power!!!

 

these subs dont sound too bad but definately not worth the money, they will blow with more that 300 wats put too them and sound very extorted at around 35 wtts deck power, would recamend buy from a dealer too not from best buy.

 

Seen em, sold em, ran em. Dual sucks. Simple as that.

 

Of course they would sound distorted at 35w, they are underpowered. Most any speaker will. (assuming volume is up high)

 

Personally I wouldn't go with Dual, one of my friends with with them in his Tacoma, and they blew within 3 weeks. Door speakers and subs. I am now a fan of Digital Audio, you can see some of their stuff at digitalaudioinc.com. I am running front door panels, and back panels in my Bronco II, and they're better than the Infinity Kappa's I had. The one's I bought are rated at 110 watts RMS per speaker, and they are loud, clean and clear. But I have found out that Pep Girls now sells Digital Audio, or at least they did a couple weeks ago. They have 12" subs for $100, and they're rated RMS of 1000 watts. Might be worth a look.

 

I had Dual subs in my Bronco the exact ones ur looking at too. And i personally loved them. I put them in and paired them with a Boss Audio Systems amp at 1000 Watt peak, and 500 Watt RMS. I only spent $300 for the whole thing.

Once i had them installed i went to school to take a midterm and everyone was amazed at what i was running. All the kids with the ricers and their high end sound systems were litterally blown away. I had a few kids try to out do me in a battle but they could never push their subs as hard as mine.

In essence not only are they budget priced they can also turn alot of heads.

 

That was my point I just did not go into detail about it.

 

Actually... no, it won't.
At what level any amp clips at is fully in your hands - you set the gain control on the amp. That's what it is there for.

Saying less power makes the amp clip, is essentially the same thing as saying that when you turn your volume down, the amp will clip.
Fundamentally, you are misunderstanding what the cause of clipping is:
Clipping is caused when you set your gain control such that you've sized your input "doorway" too small - the amp is being fed a voltage level from your head unit that is larger than what you've told it it will be.
That's all.

Also - clipping isn't nice, but you really can't call it DC.
In fact, it's nothing like DC.
It's much more like square waves - which are still fully alternating current waveforms - AC, just not sine waves.
(And if your clipping has reached the degree of being square waves - I'd suggest another hobby! )

DC is current in a single direction, as opposed to equally alternating current flows.
IF you were to clip the sine wave only in the positive or negative direction, you could create some DC offset - but that's also not a function of clipping - that would be a fundamental defect in your amp.
Even if you clip your amp severely, you won't create any DC offset.

DC is also no more harmful to your speaker than AC.
The difference?
AC makes the speaker move in and out in coordination with the frequency that the current reverses direction at.
DC, since it doesn't reverse direction, would just make the speaker move in (or out) and stay there.
Nothing else.

In fact, I often use a 9v battery, or a battery from a cordless drill to test for speaker polarity - to identify the + from the - terminal.
When your battery is touching the terminals in such a way that the speaker moves out (rather than in), you've got the + and - lined up with the + and - on the speaker.

The only consideration would be that since the speaker isn't moving, the usual cooling that would be occuring due to the speaker moving air wouldn't be happening, so you'd have to derate your powerhandling by some degree... but it wouldn't be extreme.

Clipping doesn't harm speakers...
Overpowering harms speakers.

Only two ways to damage speakers:
1) overpowering them (intentional or not - and clipping a 'right sized' amp is one way to do it!)
2) overexcursion damage (either from too much power, too low a frequency played given the enclosure design, or simply too large an enclosure given the power being used)

In both cases, 'too much power' is a risk in some context or another.
Yes - if you don't have enough power, you might not be as loud as you could potentially be... and that may make you wish you had more output from your speaker...
...but it's nothing but healthy for the speaker.
It'll run cooler, it'll last longer.

And it won't even be that much quieter!
It takes a fourfold increase in power to raise the output level of a speaker twofold.
So, feeding a speaker 'a little less' power than it can handle - or even fully half of what it can handle - is not going to be a night and day difference.
Noticable yes, but that's about it.

 

It has been proven countless times (usually by those interested in home audio) that under-powered amps are more damaging to speakers than more powerful amplifiers. This is assuming, of course that your listening at a volume that cause some clipping, even if inaudible, on the lowered powered amplifier. If you're only driving a couple of Watts into a speaker (amazing how loud a couple of Watts can be really), then the amp is going to matter if it's 35 Watts or 350 Watts. It isn't typically an issue of over vs. underpowered amps for a given speaker rating, but rathering just avoiding under-powered amps in general that you're going to feel compelled to drive hard, resulting in clipping.

Norwestie is correct in that the musical sinusoidal wave signal will be clipped at the rail voltage of the amps power supply (on both sides of the waveform) and makes it look more like a square wave as geolemon pointed out. The flattened waveworm does provide more continuous current to the speaker than would normally be there, resulting in excessive current flow, heat, burnout, etc. Also noteworthy is that, depending on the quality of the amp, you can end up with some nasty transient spikes that are associated with slamming the output of an amp to it’s rail voltage. These are more damaging to high-frequency drivers, such as tweeters. Thus it’s important to recognize that both clipping and over-powering speakers are damaging. Also noteworthy is that you can clip a high-powered amp too (obviously). The reason for the high power amp is that, hopefully, you getting the desired volume without reaching a clipping point. Finally and obviously, you can overpower speakers so, if the amp is rated more than the speakers, keep cautious that the speakers are being exercised beyond their mechanical limits or voice coil thermal limits as geolemon mentioned.