Installing the new speakers, crossovers, and second amplifier took the better part of an afternoon, but having the foresight to install the dual-amp wiring kit in the beginning did make things go easier. The amplifiers were mounted on opposite sides of an MDF panel which went into cargo space in the right rear of the hatch area. The input signal for both the amplifiers was simply taken from the headunits speaker leads, and using a few resistors I built a simple voltage divider circuit to drop the input voltage down about 50% at the inputs of the amps. This method provides high voltage, low impedance signal to the amplifiers, and allows the amps gain controls to be turned down, which in turn improves noise immunity and dynamic range. Additionally, the Punch amplifiers use something called a “differential input” which effectively removes any noise that is picked up along the cars chassis. The result was a low noise, great sounding system that can’t even be compared to the stocker. The system will easily exceed 120dB, and it has terrific clarity, as well as excellent tonality and timbre. Stereo Imaging is fairly poor, as the speakers were mounted in the factory door locations, but a proper stereo image was not part of the original goal. I’ll take good tonal balance and clarity over a defined stereo image any day!
SUBWOOFER & AMPLIFIER
So he jumped online, and after a bit of internet research informed me that JL Audio builds a Stealthbox for the tC application. This was encouraging news, as the JL Stealthboxes are truly high performance vehicle specific solutions, and in this case uses an excellent JL 10W3v3 series woofer, in a hand-made fiberglass enclosure. The JL solution is designed to go in the spare tire well, and fire downward, and only raises the cargo floor slightly. Perfect! A quick trip to the local JL Audio dealer later, he was about 700 bucks poorer, but the proud owner of a real subwoofer system for the tC.
To power the JL 10W3v3 woofer, we selected a Rockford Fosgate P300-2 amplifier, rated at 300 watts bridged into the 4 ohm load the JL woofer would represent. This amp was chosen for several reasons, first, it was reasonably priced at about $270, and second, it is a full range stereo design, so if a future upgrade was to happen, this amp could still be used to power the full range speakers simply by readjusting the built in crossover. Plus, I had recently tested a 300-2 in my lab, and I knew it was capable of delivering significantly more than the rated power spec suggests. Keeping in mind the possibility of adding another amp later, the amplifier was installed using a Rockford Fosgate RFK4D dual amplifier wiring kit, which included a distribution block, 4 gauge full copper B+ wiring to the battery, as well as an AGU type fuseholder, the individual amps B+ and ground cables, turn on wires, as well as speaker and RCA cables which we thought we might use later. Paralleling off the rear channels for input signal with a simple voltage divider, at this point the system upgrades had cost about a grand, and for a couple of months, the little tC was transformed into a bumpin’ machine with real bass. For some folks, this would have been enough, but there was another G note burning a hole in the lad’s pocket, and suddenly one day I was informed that the OEM speakers simply weren’t doing the sub justice, and needed replacement.
Rockford Fosgate P300-2