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The RKC113's are 5.25-inch coaxial speaker systems featuring composite ABS baskets, polypropylene cones with butyl rubber surrounds, 0.75-inch titanium tweeters, and external passive crossovers. The crossovers are pre-wired for ease of installation and the systems include all of the necessary hardware for both general installation and several vehicle-specific applications.
SUBJECTIVE
The tweeter on each RKC113 is mounted on a bridge that spans the midrange driver rather than a post that protrudes from the center of the mid's voice coil. While both methods have their advantages, this approach allows for the retention of a dust cap on the midrange driver. In most coaxial designs, a thin ring of foam is the only thing that stands between the mid's voice coil former and the possibility of a binding situation. The automotive environment is no place to skimp on physical protection. There's virtually no end to the array of potentially damaging particles that can end up in your car. Throw the magnetic field of the speaker's motor structure into the mix and you can almost see the catastrophe in progress. This method allows the retention of a dust cap on the midrange driver - that's a good thing. Consider that in most coaxial designs, a thin ring of foam is the only thing that stands between the mid's voice coil former and the possibility of crap in the gap. The automotive environment is no place to skimp on physical protection, thus the dust cap on the RKC113 is a clever way to avoid premature failure caused by the array of damaging particles in the automotive environment.
Sound quality from the RKC113's was relatively good overall. Their bottom end seems a bit soft, but at 5.25 inches, you can't really expect pounding midbass. Midrange response seems smooth, with only minor tonal colorations and the top end, while somewhat emphasized, is also manageable. Their reproduction of my favorite tracks caused a number of passively introspective quotes like 'Hmmmm, interesting' but never a 'What the #$@! was that?'. The objective measurements will have the last word, but these systems seem to be free from the huge variations in response that are so prevalent in automotive speakers. The RKC113's definitely provided the most enjoyable and realistic audition of this issue. (MB Quart reports that there's a premium crossover upgrade available for the RKC113 called the PXC113. This crossover has higher grade components, allows the system to be bi-amplified and boasts five tweeter attenuation steps instead of three - Ed.)
OBJECTIVE
Impedance measurements for these systems show a maximum of 21 ohms at 2.5 kHz. Minimum impedance over the systems usable range measured 3.7 ohms at 265 Hz. Average impedance measured 8.3 ohms between 100 Hz and 20 kHz. One watt at one-meter sensitivity measured 85 dB with 200 Hz to 5 kHz band-limited pink noise. RTA measurements show a smooth response that fits within a window of about 12 dB over the system's usable range. The increased resolution of our semi-anechoic measurements show a bit more deviation with an overall response window of about 15 dB.
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