Gain Controls are the Key to any system. It will alllow you to adjust to the speaker being powered.

Now if you can't keep from Turning it all the way up it's useless!

 

well when i had duals they sucked even my p5 sonys sounded better and are pretty cheaply priced and i got a 960 watt amp from pioneer which makes a nice sound.

 

Just speaking of loudness, make sure you get something with enough SPL (dB) 90 or higher is good.

 

Misunderstandings such as this are how myths get spread...
Myths circumvent understanding the issues, circumvent learning.
Several exist in this very quote above!

Lower power amps on their own do not harm speakers.
If it did - imagine a world where turning your volume **** down harmed your speakers?
That's ludicrous - it's that simple.
What IS true about running lower power is that it will cause your voice coils to heat up less - that's basic physics, and that's good for your speakers.

Also - "volume levels" don't cause clipping... misadjusted amplifiers cause clipping. Of course, there is a point where your head unit may begin to clip as well (but fewer and fewer of them, these days!) - but that's taken into account, when setting gain controls... and is not harmful in nominal form.
In fact, a small amp that is clipping the signal by 10% will be less harmful to the speaker than a large amp clipping it 10%... or even less, in fact.

You have to understand what clipping is - not treat it like some mysterious damaging demon.

Bottom line - clipping is simply increasing the time constant that the waveform remains at maximum amplitude [in both positive and negative direction], and therefore the voice coil will heat up more, in accordance with the degree of clipping.

Therefore, a small amount of clipping is hardly noticable - in fact is very normal, if the gain control is set by ear, is not harmful, and further won't even occur until you find musical transients in the music that reach the full maximum -0dB level possible in the recording.

Also - it naturally follows (and "has been proven numerous times" - inherently!) that a smaller amplifier clipping [i]so severely as to result in audibly severe square-wave type waveforms[i] still would only heat the voice coils of the speaker up as much as an amplifier that was twice as powerful, that was not clipping at all.
It is not clipping that causes damage, it is heat.
And heat comes from power...
...in the case of clipping, the power increase is caused not by amplitude increase (that is naturally limited by the maximum voltage of the amp), but by time constant increase, as you square off the waveform being amplified.

Lots and LOTS of myths out there in the "home audio world" (bubble world? ). Let's stop them - or at least understand them, OK?

This is the real issue, and it's no fault of the amplifier:
...and it isn't a matter of driving the amp hard - it's a matter of having a novice user, who wishes he had more output out of his speaker - and observes that when he turns the gain **** up and down, the volume goes up and down....
...Hey! Must be a volume ****!
Let's crank that sucker!

Again, that's no fault of the amp - that's user error.
And there's no guarantee that with a bigger amp that the user wouldn't do the same thing - let's say, to adjust the bass level relative to the front speaker level - and in that case, end up in an situation much worse than if he had a larger amp.

If you are proposing an arguement that "a larger amp is a healthier situation" - you haven't - it's still a higher liability, because clipped or unclipped, it's a larger amount of current flowing, and that's what causes heat...
...and again - thermal damage is one of only two ways to "blow" subwoofers.

Overexcursion damage is the other way - and that can be caused by having too much power (relative to the enclosure design) as well.

My points nearly exactly.

I'd simply stress that if an amp's gain controls are set properly, you will NOT reach clipping by increasing the volume (unless the head unit clips - and if so, that point is simply regarded as the maximum volume - and would be nominal clipping regardless).

Or, in other words, clipping is caused by overdriving your gain control - which is a 'set it and forget it' setting on your amp - NOT with your volume ****.

 

I'm not sure how we ended up on this thread, based on the initial question of wether or not "Dual" was a good brand for subwoofers. I sure hope I didn't digress us from the topic...

I think that geolemon and I agree on everything, except the general damage that can be caused by under-powered amps. That could probably go into an unecssary, unhealthy, and excessively long debate about harmonic distortion and is a mute piont anyway as anyone driving an amp that hard has got to be asking for trouble. But then I've have to jump in and disagree about cone material too. I'll save that for the Rodney King thread...

However, as geolemon pointed out, setting an amps gain controls appropriately should elminiate that potential, exlcuding clipping from the head unit which is typically only seen today with amps driven by the speaker outputs of a head unit rather than line level outputs.

Getting us back to the topic, I've never tried subs from Dual, but if they look structurally sound and sound good to you (if you have a chance to hear them before you purchase them - as I always suggest), then it's just a matter of personal preference. I agree with 93GreenF150 that Rockford is probably a better sub, but honestly, it's what works for you.

Happy thumpin' and I hope to see some pics!

 

Good point...

Perhaps a moderator could split this discussion into it's own thread?

It's a discussion worth having - it's one that enters into every single amplifier customer's mind.

 

True enough, issues like clipping, capacitors, recommended amp power seem to come up a lot and should probably have some dedicated space somewhere. Could help new visitors too....

 

I agree, this should become a seperate thread, but first i'll answer the origional question. If you want something that is gona make your ears bleed, don't hold your breath waiting for it to happen from the duals no matter what amp you use. If you want some more kick than say a 6x9 or your stock stereo/speakers, a cheap set of subs could do the trick, just don't crank it up too high. I had a cheap pair (actually got them free from Circuit City with amp purchase) of Baja 10" subs, driven by a cheap 250 Watt amp (peak). I ran them in parrallel in a 1.75 cubic foot box i custom built. Put it behind my seat and it hit pretty good. I would say Duals are about the same quality, but i wouldn't spend more than $40 for 2 of them, check out eBay, the were selling Baja's for $5 a while back (2 years).


Now for the other topic on amps:
My common sence rule of thumb, if it sounds like your speakers are distorting, clipping, or if they sound like they are bottoming out, or being over driven, you either have the gain/volume too high. Thats all there is to it. The reason why it is too high varies.

First, your amp is being over driven. You may have an amp which you have cranked up way to high, causing it to not have a smooth wave coming out, but rather a square wave, meaning current and voltage are staying constant for some period of time. This causes the speaker to stop moving and heats up the voice coil(s) eventually burning up and bye bye speaker. Basically you are trying to get your amp to swing the voltage higher than what it can deliver, and it is maxed out. The answer, turn down your gain on the amp, or volume on the radio. You may get by with the gain all the way up on the amp at lower volume levels, but when you crank it up too high, you will have to back the amp's gain down.

Secondly, your speaker is being over driven by either the amp or its ENCLOSURE. If a speaker is not is the proper side (volume) enclosure, you will cause the speaker to be pushed in or out to far under higher volumes, even if the amp is delivering at or below the speaker's rated wattage without clipping/distorting. But, also having too much power to the speaker from the amp will also cause this to happen. The answer, you guessed it, turn down the gain on the amp, and/or get a better enclosure. **Enclosures are supposed to be designed acording to the speaker's specifications, not whatever the store has in stock. Often it is better to build your own tuned box.

Therefore, you can take any amp and any speaker and run them (as long as the impedances match) and have no problem, as long as the power of both the amp and speaker are not being over driven. SIMPLE AS THAT. If it sounds like its being over driven, it is.

The funny thing is all these people who puts the subs in their trunk and you won't hear it being over driven!! Quality also sucks when you do this, unless of course you can pop the rear seat down and expose the trunk. My ideal setup is a sub right behind your a**!!

I've got a 10" Alpine dual voice coil run in parallel (total impedance 2 ohm) driven by a bridged 2 channel 250W alpine amp, and a custom box. Only cost me $200 for everything, and it sounds great. Sure you won't hear it rattling my license plate down the road, but thats not what i was going for. I wanted some kick and better bass response than the 6x9's in the rear.

 

well they say you learn something everyday, and today by spending a half hour reading the clipping encyclopedia posted by you guys i've learned something.