Why pay more for a JL audio amp?

[helotaxi 5,000+ posts]

I have a question about the variable impedence same wattage thing with the JL's. Does this mean that no matter what the dynamic impedence of the driver is it will deliver the exact same wattage? And I mean dynamic impedence as in when it is playing music and what have you.

The power is based on what you set with the gain control. There's a reason that they tell you to set the gain the way that they do. It configures the voltage rails in the power supply as well as matching the input sensitivity to the input voltage. From there the amp's power supply "knows" how much current that it should be providing to deliver rated power. If the voltage across the load attempts to draw too much current, the amp either rolls back the voltage or goes into "low impedance" protection. There is nothing dynamic about the R.I.P.S. amps except the protection circuitry. Besides you wouldn't want an amp to adjust output to provide the exact same power across the entire freq range regardless of actual driver impedance at any frequency. Think about the result of applying more power into a driver in a ported enclosure right at resonance. The impedance is highest there but the system is also at its most efficient there to compensate for less real power being applied due to impedance rise. Add the extra power there and the result would be the same as boosting an EQ band centered at tuning with a Q the same as the box. Not exactly high fidelity at that point.

This is different than the PG Xenons that actually measured the DCR of the drivers connected to them on startup and configured the power supply accordingly. With those the amp treated an open circuit like a 4 ohm load so when setting the gain you used 4 ohm voltage numbers regardless of the load that you were actually running because you were only voltage matching the input.