Eminence Kilomax pro 18 two different PDF file specs???

[killersoundz]

Ok...

http://www.parts-express.com/pdf/290-434s.pdf

http://www.eminence.com/pdf/Kilomax_Pro_18A.pdf

Different specs...which one to believe?

[killersoundz]

I'll take the Eminence site as the most recent. Those specs make this woofer even more picky than previously thought. No wonder people are blowing them so easily, if you put it in any decent size enclosure it will explode with that much power.

[AMC]

What about them do you find makes them 'picky'? Seem fairly vanilla to me.

[Chris Roemer]

What about them do you find makes them 'picky'? Seem fairly vanilla to me.

Drivers with higher "Q"s (say, in the .50's rather than the .30's or .40's) have less leeway for box volume/tuning errors when you try to vent them.

[Paul O]

These drivers are terrible.. really only capable of handling about 500w before exceeding xmax, the Definimax is a far better performer.

[PunkSweeper]

Looks like a driver to cram into a tiny sealed box and flush with watts. The heat sink makes for high thermal power handling, right?

[billfitzmaurice]

Looks like a driver to cram into a tiny sealed box and flush with watts. The heat sink makes for high thermal power handling, right?
It's a driver made so that in OEM applications the seller could say
2500 Watts! Peak

[killersoundz]

These drivers are terrible.. really only capable of handling about 500w before exceeding xmax, the Definimax is a far better performer.

You have a point, but I wouldn't say they are terrible. The Kilomax will go in a medium size box (6-7 cu ft) tuned to ~39hz and take every bit of 1,200 watts. It will be over xmax considerably at 60hz but it will hold together according to specified "xlim" (theoretically). My buddy recones drivers out in LA and he does more Kilomax's than anything, so that may not be a good sign, but also people are kind of ignorant in general and try to slam them real hard, or dont use a 24db HP filter at 35hz.

Either way, the smaller the box the better with these guys.

[killersoundz]

It's a driver made so that in OEM applications the seller could say
2500 Watts! Peak

Well, even you have to admit that 1,250W RMS handling claim is a pretty strong selling point to the buyer. I wouldn't necessarily blame them for that.

[killersoundz]

Looks like a driver to cram into a tiny sealed box and flush with watts. The heat sink makes for high thermal power handling, right?

The issue is the suspension can't quite keep up with the thermal power handling in most enclosures.

I saw a pair of these drivers stuffed into some HUGE yamaha sub boxes on criagslist. A buddy of mine that just opened up a local venue/bar was going to buy them until he asked my opinion and I said NO. Such a misaligned enclosure for that speaker, it would die with 400 watts.

I'm sure the majority of the Kilomax's end up looking like this

http://www.speakerrepair.com/repairpicshtml/emin-kilo18-before.jpg

[badman]

Yes, they seem like a step down from the monster Magnums that preceded them. The magnums had what seems to be a nicer motor (undercut pole, shorting ring below the gap, and the big honkin' phase plug above) as well as similar extremes taken for ventilation. Both the 18" and 15" magnums had about 30mm Xlim vs. the 20mm claimed for definimax.

[billfitzmaurice]

The Kilomax came before the Magnums, which are now called Definimax, only the name was changed. Kilomax 18 has the higher xmax and xlim, Definimax 4015LF has the higher, which is a bit odd. IMO the Kilomax was introduced at the behest of some OEM users, like Carvin, who wanted something to beat JBL and EV, at least as far as power ratings were concerned. The heat sinks accomplished that, but with cones and suspensions unable to handle the power they quickly faded from OEM use, probably as a result of a very high warranty return rate.

[AMC]

Not to be a fly in the ointment here, but it seems to me, that you are criticizing the driver, because it can't handle misuse in inappropriate boxes. :confused:

As far as power handling goes, I believe it was an engineer by the name of Schotz who said years ago, that anything beyond about 250watts, was merely power dissipation.

I would word it more like this, If you can't reach Xmax with 250watts in to a driver, you need new drivers, not more power. (not always true, but you get the idea)

[Randy L]

IMO the Kilomax was introduced at the behest of some OEM users, like Carvin, who wanted something to beat JBL and EV, at least as far as power ratings were concerned. The heat sinks accomplished that, but with cones and suspensions unable to handle the power they quickly faded from OEM use, probably as a result of a very high warranty return rate.

I remember when Carvin used the Kilomax drivers, but it didn't last long. They moved on to the B&G drivers now.

[killersoundz]

Not to be a fly in the ointment here, but it seems to me, that you are criticizing the driver, because it can't handle misuse in inappropriate boxes. :confused:

Something like that. But Bill is entitled to his opinion, and especially considering he is a guy that believes in making SPL with minimal watts it's only natural for him to hate this driver. I can't disagree with him, but everyone knows power handling numbers are the first thing amateurs look at when buying pro audio speakers.


As far as power handling goes, I believe it was an engineer by the name of Schotz who said years ago, that anything beyond about 250watts, was merely power dissipation.

I would word it more like this, If you can't reach Xmax with 250watts in to a driver, you need new drivers, not more power. (not always true, but you get the idea)

Well, the difference between 250 watts and 1000 watts is that 1000 watts will theoretically give you 6dB more output. 6dB is pretty considerable.

[billfitzmaurice]

Well, the difference between 250 watts and 1000 watts is that 1000 watts will theoretically give you 6dB more output. Not if you're getting 4dB of power compression at 1Kw, which is about average. I find for the most part 500 watts is about as much as you want to give one driver, as above that between excursion limits and thermal power compression the rate at which returns diminish is very high.

[Paul O]

Not to be a fly in the ointment here, but it seems to me, that you are criticizing the driver, because it can't handle misuse in inappropriate boxes.

No.. the problem with this driver is even in an appropriate box it can't handle anywhere near it's thermal power rating before exceeding xmax.. the suspension is too weak or that fancy heat sink is too heavy or something. It isn't uncommon with these larger drivers to run into excursion limits a little before thermally stressing the voicecoil, but when you can't even get half way to the rms power rating that is just sad. The only reason nobody gets thier nose completely out of joint about the kilomax is because the price isn't totally obnoxious.. like what you would have to pay for an EVX-180b for example.. the driver that completely owns the worst sub/$$ rights.

[killersoundz]

Not if you're getting 4dB of power compression at 1Kw, which is about average. I find for the most part 500 watts is about as much as you want to give one driver, as above that between excursion limits and thermal power compression the rate at which returns diminish is very high.

Yeah I hear ya, I did put the word "theoretically" in my statement for that reason.

But Bill you have to admit this is one heck of a sub, rated at 1700w RMS, 16mm xmax:

http://www.bcspeakers.com/CPD/product_pdf.php?id=0000000162

[badman]

The Kilomax came before the Magnums, which are now called Definimax, only the name was changed. Kilomax 18 has the higher xmax and xlim, Definimax 4015LF has the higher, which is a bit odd. IMO the Kilomax was introduced at the behest of some OEM users, like Carvin, who wanted something to beat JBL and EV, at least as far as power ratings were concerned. The heat sinks accomplished that, but with cones and suspensions unable to handle the power they quickly faded from OEM use, probably as a result of a very high warranty return rate.

Definimax drivers do not have the phase plug in eminence's information, and their specs are fairly different. This is not the same driver as the Magnum 15HO or Magnum 15LF, it bottoms out at 15.5mm vs. 30ish in the magnums, for example. The Fs is higher and Vas lower.

But the limitations with the Kilomax do seem obvious, that much power is too much for any driver, like you say.

[AMC]

No.. the problem with this driver is even in an appropriate box it can't handle anywhere near it's thermal power rating before exceeding xmax..

All other things being equal, if driver 'A' hits it's 10mm xmax at 200watts, and driver 'B' hits it's 10mm xmax at 750watts, which one is louder at xmax? Who cares what it's thermal power rating is, that is a spec for 17 year old kids buying car stereos. Does this driver make reasonable quality and quantity of sound for the desired application and price? That is really the only question.

[AMC]

Not if you're getting 4dB of power compression at 1Kw, which is about average. I find for the most part 500 watts is about as much as you want to give one driver, as above that between excursion limits and thermal power compression the rate at which returns diminish is very high.

Taking power in and not converting it in to sound would be power dissipation.

The article I mentioned, by Larry Schotz, came out in a car stereo mag in the late 80's, when the first 1K-watt drivers were being introduced. It was a very funny read, and if you can find it I would recommend giving it a few minutes. Then, those 1000watt driver were about 6db less efficient then other drivers, thus you needed 1000watts to get the same output as 250 in others. Ridicules, and worthless. But it sounds like that what some people want here, everything needs to be able to reach xmax right at rated power. That will just result in inefficient drivers.

[Sydney]

Well as mentioned earlier: the effect to current running through VC wire ( approx #29 ) quickly causes heat loss effects starting @ -10db of max power.
By the time hundreds of watts are applied half of it is heat loss.
The idea of running a driver near full power is grave misunderstanding.
Average music power is quite low and the top of the power curve is for crest factor.
A increase from 1 watt to 10 watts is 10 db; as is the jump from 100 watts to 1000, but the thermal impact is immense.
JBL's Doug Button shows in his AES papers ( Heat Dissipation and Power Compression in
Loudspeakers ) how fast and how much the T/S specs change when a driver get hot from power.

[wg_ski]

Average music power is quite low and the top of the power curve is for crest factor.


Simplified example that may be easy to understand. A sine wave at 40 Hz, at 50 volts. Requires 300 watts to reproduce before clipping. Add the second harmonic at equal amplitude (50 volts at 80 Hz). Now the required amplifier must produce 100 volts (the peaks will add if they're in the proper phase, and if the tones are NOT harmonically related it's a mathematical certainty that they will some of the time) - that's a 1.2kW amp, producing a whopping 600 watts of average power - and that's just with a CW tone. That will shut most amps down in minutes if sustained. If it's effectively 50% on, 50% off you get 300 watts of thermal load on the speaker, driving a 1.2kW amp to clipping. And only 150 of those watts are really taxing the woofer with excursion - it's loafing with the higher frequency tone(s). Now music is a much more complex waveform (with higher crest factor) than a simple tone and it's 2nd, gated on and off.

[billfitzmaurice]

Taking power in and not converting it in to sound would be power dissipation.
.Dissipation may be what's happening but the correct technical term is thermal power compression. It's the number one source of driver failure in pro-sound. Voice coil resistance increases as it gets hotter, and what many users do when the driver goes into compression is to turn it up louder. That makes the voice coil even hotter, and the result is less volume, not more, so they turn it up some more, and eventually the long term heat build up toasts the voice coil.

[badman]

Dissipation may be what's happening but the correct technical term is thermal power compression. It's the number one source of driver failure in pro-sound. Voice coil resistance increases as it gets hotter, and what many users do when the driver goes into compression is to turn it up louder. That makes the voice coil even hotter, and the result is less volume, not more, so they turn it up some more, and eventually the long term heat build up toasts the voice coil.

Same thing as "Thermal Runaway" in a regulated/compensated circuit.

BTW: You should have posted the Definimax/Magnum thing on April Fool's, cause you had me digging up datasheets "It's still available?!" Sadly, they just don't make anything quite as serious today.