Ohm's Law states that power, and in this case power lost, equals current squared times resistance. Let us take a case with any typical amplifier playing music or a sine wave burst for a period of time where half of the time is loud and half is quiet, just to simplify the situation. Let us also pretend that during the loud times the amplifier draws 1,000 amps and during the quiet times it draws 0 amps. Suppose for a moment that during a loud time, 1,000 amps of current are being pulled on a 12-volt system through a 10' run of 1/0-gauge cable. Standard resistance for this length of 1/0-gauge cable is about 0.0012 ohms. Using the previously stated formula for power lost, 1,000 amps times 1,000 amps times 0.0012 ohms equals 1,200 watts!!! So during this loud time 1,200 watts of power is being lost on that cable alone, and of course during the quiet time 0 watts of power is being lost since the current being drawn at that time is zero. With that said, half the time 1,200 watts are being lost and half the time 0 watts are being lost, for an average loss of 600 watts.
Now let us take that same example with HT's ability to current-average for the same period of time. So instead of drawing 1,000 amps when loud and 0 amps when quiet, it draws 500 amps continuously. If we put that number into the formula for power (loss) we will see something interesting. Five hundred amps times 500 amps times 0.0012 ohms equals 300 watts loss in the cable. The losses are cut in half! So while the "average" efficiency of the T15kW amplifier itself may be similar to other amplifiers, it makes the entire system from battery to amplifier outputs much more efficient.
I hope this helps explain the technology-it is REAL, and it does work.
Rockford Fosgate Design Engineer, Anthony D'Amore
Car Audio & Electronics: How did the initial idea of the hybrid amplifier evolve?
Anthony D'Amore: There were several things that took place for me that led to the design of this technology. My father has had multiple heart attacks and, during one episode, had to be shocked repeatedly by a defibrillator to bring him back. I remember being in the waiting room thinking about the defibrillator and what a great machine it is. How can a portable device with a very small battery system deliver such huge bursts of power? I knew the answer to the question, but the real question was: Could I use it in amplifier design? A couple of years later I found myself days before the annual Rockford Corporation Sound-Off, which is an SPL competition for employees. At this point I was the defending champion of three years and wasn't sure how I was going to outdo my performance from the previous year. I had an old 1980 Datsun station wagon that I used specifically for these events. It had only one battery and a 60-amp alternator, so I could not rely on that system for any serious power. But I thought, I need a lot of power for a short period. I went to work on building an amp just for this. It consisted of a power supply that converted 12 volts to 140 volts and a dozen motorcycle batteries to hold the charge. I didn't have any Mosfets on hand that would handle the heat, so a couple of colleagues I and designed a system to liquid cool the devices. We got it finished just hours before and didn't know what it was going to do, so we had the amplifier connected to an Audio Precision test system DURING the competition. After several rounds of competition and adding ice to the cooling system, my team of madmen and I walked away as victors and the prototype amplifier, dubbed the "D'Fibrillator," belted out 15,030 watts RMS while keeping its cool! That set the mark, and now we just had to figure out how to turn it into a useable amplifier that could sustain music at these levels; and enjoying music as much as we do, the amplifier had to sound great doing it.
CA&E: The foundation of the hybrid amp appears to be its energy storage ability, the capacitor. What industry was the capacitor technology sourced from and what was its intended use?
AD: The capacitors in the T15kW come from the power industry, as in power generation, transmission and distribution. The intended use for these capacitors is for very large wind-turbine energy generators, like the type seen around Palm Springs, CA. They are also finding homes in hybrid vehicles.
CA&E: What was so special about this technology that made it suitable for the hybrid amp?
AD: The great thing about these capacitors is their ability to store so much energy in a small package. (Each capacitor used in the T15kW holds about 5,500 percent more energy than a common electrolytic capacitor of the same physical size.) This, along with their very low ESR (equivalent series resistance), made them a good match for something that is charging and discharging them repeatedly.