Leaderboard

Now for the final step in my front grounds. I got all the cable crimped and ready for installation. I last left off with some grommets in triangle configuration. This is what I came up with. Here is the bracket formed and the grommets installed. Here I've got the bracket and alternator assembly on the workbench. I've installed and oriented the ground cables allowing me to place my hold-down. I've got the mounting points drilled and tapped for the hold-downs. I have also spot faced both sides of the rear bracket where the alternators mount for my grounds. Here is a close up of the triangle hold-down bracket installed in the rear alternator bracket. Here is the final assembly ready for installation. With the bracket and alternators installed I can start attaching the ground cables to the frame ground locations. Here is a shot looking up at the installed grounds. I used some steel spacers to stack the ring terminals without having to go around the bolt in a flower pedal pattern. Here is a straight shot as the grounds. Now time for some power cables. Better get back to work.

^^ This guys, not everyone is as familiar with this process as some of us may be. Like Sean said, play a 2500hz tone with the crossover set to off or flat and measure the output voltage (DMM should be set to measure AC Volts). It doesn't really matter what the voltage output is at this point. We are simply measuring the output voltage now so that we have a baseline to work from. To find the -3db point, and your target voltage, you would multiply the voltage you measured by .707. Then turn the crossover back on and adjust the crossover dial until the voltage decreases to the target voltage you just calculated. When the voltage reaches that target voltage, the crossover is set to 2500hz. So, for example, let's say you play the 2500hz test tone and measure an output voltage of 5V with the crossover set to flat (or off). Then your target voltage for a 2500hz crossover point would 5 * .707 = 3.535V. So turn the crossover on and measure the output voltage while adjusting the crossover knob. When the output voltage drops to 3.54V, that's the -3db point of the signal.....meaning you successfully set the crossover to 2500hz. For those that don't know, for a standard Butterworth crossover (the type of crossover found in most, but not all, amplifiers) the crossover point is defined as the -3db point of the signal. Hence why we know that the crossover is set to 2500hz when the signal has decreased by -3db. And we calculate the -3db point of the signal as the point where the signal has decreased to .707 of it's original value because for voltage the conversion to decibels is 20*log(Voltage1/Voltage2). So 20*log(1 / .707) = 3.01db. Therefore, the point where the signal has decreased to .707 of it's original value is the -3db point of the signal, and the -3db point of the signal defines the crossover point Now you know, and knowing is half the battle.