Si Magnum D2 Info...continued From Caf

Should be 50% on the surround. That is pretty much typical as about 1/2 of the surround will radiate in a forward motion.

"Superwoofer" is being used to describe any long throw, or I guess I should say, extreme throw, drivers. Personally, I feel the term is considerably overused. IMHO there are really very few drivers that utilise enough techology for flat BL and KMS curves to be considered "Super". But alas, that is just my opinion.

While the driver is rated at 600 watts, I believe it is capable of more Pmax than that. Nick stated the coil is 2.3 inches tall and 3 inches in diameter. That leads me to believe it is capable of a bit more Pmax than indicated. I am sure part of the mention of 600WRMS is for warranty concerns.

Also of note, mechanical p-p is 2.6 inches with an Xmax of 24MM 1 way.

 

im remembering 1kW+ is the capability of the woofer. i could easily be wrong, but thats what i remember

eric

 

I've seen a Magnum get tortured with 1800w full blast free air with no problems whatsoever. I think I remember Nick saying the coil is as big if not bigger than the ED A series, and I know the coil is longer than the Brahma, and both of those subs have been known to handle a solid amount of power. 1000w give or take 500w is pretty good for the sub, but just like most subs, it wont need that much to get moving. Really anything from 400w-1500w is safe as long as you use it properly.

 

As far as the power handling is concerned, i think SI has taken a lil lesson from JL. I've heard the Magnum can handle tons of power, just as all the other "Super Woofers" can. I talked to Nick for a solid 3 months about that woofer, tryin to decide if i wanted it or not, and from what i learned of the woofer, that 600wrms, is just like the 500wrms of my Dub Sebbin. Seems it should get going very well with 600wrms, but you can give a hefty amount more without worry.

 

Most subs can take more power than manufacturers specs would indicate. There are a few other things to take into account, however. Box size and type affect power handling...common sense, though. Also, just because you have 1500 wrms (or whatever), doesn't mean you have to "use" it. My 15A has never seen the ~1500 wrms my Tantrum puts out. My 10k hasn't seen anywhere near the ~750 wrms my Tantrum puts out at 8 ohms. My old school Solo 8 incher...ya' know...and of course, the very dynamic nature of music ensures that the driver doesn't see full power from it's amp for extended periods of time. I would say to just use common sense and listen for any abnormalities that might indicate the sub is being overdriven/abused.

I thought I read that ED uses the 1/3 surround method...but who knows. The difference in SD, and it's subsequent difference in output, is negligible.

BTW, has anybody seen that video of the Shiva on Adire's website...bouncing nicely off of just 60 wrms?

 

A friend of mine just gave a Magnum 2400w and it did a 150.3 on an AC mic last week...so yes, it can handle the power..not too much more though

 

Well "burping" and "continuous" are really two WAY different ends of the spectrum.
Thermal failures happen due to.... (drum roll) HEAT! :lol:

So, whether you slow-cook your chicken in a smoker, or nuke it in the microwave, you can overcook it either way.
And no one wants to be left with a plate of overcooked chicken.

There are many factors that contribute to a woofer's ability to handle power... one is the use-time-period being considered (similar to "duty cycle" for a motor or tool), one is surface area, the type of glue used, cooling technologies built in, etc.
It's not just about VC dimensions.

 

I think you are right, in your observation of people recommending a 600w woofer for 1200w continuous use... I agree.

But put a different hat on for a second.

why the interest in power handling?
Why would you care how much power it can handle?

If you can get the woofer to reach full excursion and output on 600w, sending 1200w to it won't gain you anything but overexcursion damage, and possibly thermal damage if not (and if not overexcursion damage at that power level, that would generally indicate an enclosure that's WAY too small! )

To me, a "super" woofer would produce high output levels without requiring massive power levels.. that would describe an inefficienty woofer, actually...
The more output, given less wattage (for a given size enclosure), the more "super" it is! :lol:

 

this is a simple question to answer...its to know exactly how much power you can feed it. if it says 50 watts, you shop for a jbl/crown, if it is 100 rms, you get a pair, and strap them on it, and so on and so forth...basically the formula says that you take rms / 50 = Wattage x 1000 = power level to shop for :bye:

eric

 

All depends on box specifications, and what frequency you play...I can play a 20hz note on my Magnums and get 2.6" no sweat....do it at 50hz...different ballgame...

I thought I knew how Nick measures his cone area...guess I'll have to have him refresh my memory...

 

Well... bear in mind this is not only normal, but this MUST happen if your subwoofer has anything even resembling a smooth, linear response plot...

This is true for all loudspeakers, any frequency range:
As you decrease in frequency, you must reach proportionally greater and greater excursion levels to produce the same level of output [in a non-ported application].
And really it's displacement, not excursion, but your cone can't change shape on the fly... so displacement can only be changed by increases in excursion.

But it all happens quite naturally, because a decreasing frequency means less cycles per second, meaning there's longer time duration between positive and negative peaks - the woofer has the same amount of power going to it [as higher frequencies] - so it has more time to travel either in or out - it'll naturally reach the proportionally higher excursions.
Consider maximum (or average) cone velocity to be a function of how much power you send into the woofer, so that would be a constant if you are comparing two frequencies played at the same volume... it makes sense that because the lower frequency's signal changes cone direction fewer times per second, it'll go farther in each direction.
Just like driving 30mph down the road, and seeing how far you travel in 10 seconds, compared to how far you travel in 20 seconds.

(and in a ported application, you must factor in the phase relation ship of the port to the subwoofer, and both how they combine in terms of output, and how the port contributes to the forces inside the enclosure as that phase relationship slowly shifts, as you traverse the frequency range )

So if you were reaching full excursion at 20hz, AND reaching full excursion at 50hz, you'd have one hell of a peaky response! The subwoofer would sound more than 2x louder (given that 50hz is more than 1 octave higher than 20hz, and that lower sounds generally sound louder to us by impression)!

This is also why small tweeters with a millimeter of excursion can drill our ears out, while 12" subwoofers with massive excursion offer similar output levels. B)

 

Ok ok.

We measured our Sd with typical T/S measurements. Unless we made a typo on the web page, our Sd should be slightly lower than the 12a because the 12a does have a gnats fart more Sd than we do because of the narrower surround that they use.

The power handling of the driver was/is rated by me. We do not cover blown coils, so you can send it anywhere from 100 watts to 3000 watts if you want. Sending it an unGodly amount of power would be like buying a new car, wrecking it on purpose, and wanting the dealership to warranty it. I rated the power handling based on the industry standard 4 hour free-air rating. I have always been a big fan of rating products the way they should be - not trying to hype up the numbers just so it looks better. There was no lesson from JL on power handling, although I do really like the way they rate their drivers. The drivers will handle in excess of 1000 watts from an amplifier all day for daily driving purposes. Although if you listen to sine-waves the entire time you might want to use a little bit of common sense and turn it down occasionally.

The coil is 2.3" tall and 3" diameter like others have mentioned with 20 gauge aluminum windings. Along with the venting we have from the motor and basket, it can take a LOT of power.

I need to go search CAF for the thread you're talking about. No one even mentioned it to me.

 

Oh, don't bother... Warbleed closed the thread as the immaturity level was dropping radically.

Just curious about the RMS rating...
In running it "free air", weren't you more limited by physical excursion constraints rather than heat-related constraints?

It's an interesting way to rate...
I've always conceived powerhandling as two separate ratings:
1) thermal powerhandling
2) mechanical powerhandling

The former is based on how much heat the VC can dissipate over some extended period of time (and is typically what I think of, when I hear "power rating".

The latter is a function of excursion, given a particular enclosure. That is, the excursion reached by a woofer that is fed a certain amount of power changes as you change the enclosure. In particular, excursion increases as you increase enclosure size (assume sealed), until you get to the point where there's such a large enclosure as to be no enclosure at all (free-air, where there's no air-spring to augment the driver's suspension).
Because of this enclosure dependency, this is something I generally pictured publishing more in the form of a chart... powerhandling on the Y-axis, enclosure volume on the X-axis.. something along those lines.

By simply rating based on the mechanical constraints of the driver in free-air, I can see how this would be arguably the "most conservative" means of rating the woofer...
But in the same respect, wouldn't it likewise be handicapping the output of the driver, if I put it in say.. a 1.25 cu.ft. enclosure, and only fed it 600w?
That's obviously the flip-side of the coin... what do you think?

Or maybe I'm wrong, and the 600w is somehow more tied to thermal given your test... I don't know the details. B)

 

It's a thermal rating. Depending on the frequency (or frequency bandwidth that you use), and the enclosure used, mechanical limitations change dramatically. For instance, 600 watts on a Magnum in a 1.5 cube sealed enclosure at 50 Hz isn't going to even come close to its mechanical limitations. And besides, since the power rating is in free-air, putting it in any enclosure boost the power handling. But the driver will/does handle 1000 watts from an amplifier very well. We just chose to rate ours the way that Focal, Dynaudio, Morel, Scan-Speak, etc., rate their drivers. Sure it's a little conservative but that hasn't stopped people from throwing a lot more power on them.

 

And as you said..
The warranty isnt' with regard to actual "power applied" (and good luck trying to enforce that one anyway)
But rather simply, the warranty just simply doesn't cover thermal failures... and it sounds like thermal failure point is somewhere well over the 600w mark.

I'm all for conservative ratings, believe me. Hard to argue that it's the enthusiast's fault when they thermalled their sub on a 1000w amp (if you had it rated at 1000w, for example), because they were clipping their amp into outputting downright square-wave-like waveforms... :lol:
But at 600w.. even with abuse like that.. on a 600w amp, probably not likely to cause failures. Makes sense.