This is a question that shows up all the time, so here is the why and the how.

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LDLC drivers are designed to work at Max Long Term Output levels with bursts mixed in. Since CEA testing does not allow the coil to heat up enough to mimic real world content (music & movies), the closest relation to real content is Max Long Term Output.

You can look at it this way, CEA is the most ideal conditions for the drivers internal motor function, Max Long Term is the reflection of the drivers ability in the most non-ideal conditions. Where LDLC drivers are designed to work is in a blend of the two with a bias towards Max Long Term. 

In terms of content playback: CEA - optimistic numbers, Max Long Term - conservative numbers

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Now for the "why" question. When a coil in a linear motor (sinus wave) is fed wattage (volts x amps) the resistance (Re in Ohms) impedes the flow of electricity. This creates heat. When heat is introduced into a magnetic field, the strength, shape, and overall ability of that field changes. This means that a driver at "running temperature" will not measure (TS params, Klippel, or CEA) the same as a cold driver, because the cold driver has it's full BL compliment. 

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So what does this have to do with driver simulations? The answer is everything. 

You see, we guarantee Xmax performance from a simulation in real world content if your amp and box accurately represents your simulation. Remember, that is a sim, no physics accounted for because the software can not determine coil temps, and yet we are able to guarantee it's performance from simulation (void of physics) to Xmax in real world content (all of the physics included). To my knowledge, we are the only speaker driver company on the planet that offers this guarantee.

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How to sim drivers and M Series products: The Range Method

Now that you have an understanding of what the guarantee actually means for you as an end user, you can sim the driver and get results that you can count on. 

Xmax is guaranteed to perform below audible limits of distortion and compression and the real world output will be true to the simulation if your amp and enclosure are true to the simulation. This is your baseline and everything below Xmax it is good to go.
Xmech minus 2-3 mm is where we target our end of the line.

Sim the unit on its intended power range from RMS to Peak power and use Xmax and Xmech minus 2-3mm to develop your range from Xmax (guaranteed) up to Xmech minus 2-3 mm (potential).
If you can get your hands on more real/proven numbers for your amp, use those.
To get a sampling of what the driver can do on lower power, sim at all kinds of power levels using the Range Method, and you will see its capability across that mechanical range on your chosen power.

 

If you simulate and think "wow, that doesn't seem that much better". Remember Xmax is guaranteed performance in long term output conditions (the closest relative to real world content). When CEA is referenced instead of long term output, the coil does not get hot enough to reproduce the effects heat has on output, namely distortion and compression by affecting the magnetic field of the motor through its stroke. This change in the motor can be heard as a "weight" or a "thickness" to the sound. CEA numbers can be as much as 3-9 dB higher than what the driver can reproduce in real world content. Bear this in mind.

We design our drivers to run hot on real content which is a closer relative to Max Long Term Output than CEA burst. As CEA burst doesn't allow the coil to get hot enough to produce the ill effects of running content, we find that the LDLC model is better served by "laying the boots" to our drivers by referencing long term output. You can look at it this way; CEA is an optimistic measure, max long term output is slightly conservative, cautious. We err on the side of caution.
Why we don't use other excursion/cone travel measures is because we substitute the travel measure for an actual guarantee of LDLC performance up to the limit of Xmax on real content, while Xmax is a universally understood measure. This guarantee plus the range simulation method will show you exactly what you can expect at Xmax and what you can possibly achieve at just below Xmech given the enclosure and amp are representative of the simulation.

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