Q. I'm having a problem with my current sub setup. I've got four, dual 1.5 ohm 13W7s hooked up to a Cadence DCA-2500. It's rated at 2,500 watts at 1-ohm RMS. The subs are in a sealed box; the amp is out in the open with plenty of air. I have DB Link Strandflex ought-gauge wire and a 300-amp Stinger fuse and fuse holder. Power and ground are ought-gauge. I sanded off the paint so the ground is mounted onto straight metal. The amp gets incredibly hot. I can't even touch it, because it gets so hot.
I've had other amps and they all get hot. Even with two subs at 1.5 ohms, it gets way too hot. The battery is stock and the alternator is 120-amp Delco. But I also had a SL1000 on one W7 at 3 ohms that got way too hot also. It blew up.
Is there something I'm doing or not doing? Is the gain set right. I just can't figure it out. Please shed some light on this situation so I can keep my amp running.NathanIllinois
A.For starters, amplifiers are notoriously inefficient and vary with the classification of the design. For example, if your 2,500-watt amp is the still common Class AB type and a healthy 70 percent efficient, it would churn out over 1,000 watts of waste heat while it gives you the remaining 2,500. In case you added it up, your amp would need to consume 3,500 watts if you want to get 2,500 watts of sonic energy out of it. At 14 volts of potential from a healthy electrical system, you'd need at least a 250-ampere fuse for this one amp. As you move to more efficient classes such as Class D, you get more sound with less heat-a very important point if you have a limited electrical system. At this point, I don't see a big problem with ought-gauge wire and a 300-amp fuse, so let's look a little deeper.
If this power circuit is being shared with the rest of your amps, you may be passing the point of voltage sag. When the voltage to an amplifier is inadequate, the amplifier will fight to deliver power under limiting conditions-like running a marathon high in the mountains where there isn't enough oxygen in the breathable air.
Here is a simple way to track down if voltage sag is your situation: Get your hands on a digital multimeter and start taking measurements. At the amp terminals, the DC voltage should read over 12 volts with the amp playing at a mid to high volume. If not, you can start moving to other areas to test. At this point, I'd perform a "touch test" to see if any components are getting hot. This includes wiring, terminals, ground points, fuse holders and any other type of connectors. If, for example, you find that your fuse holder seems very hot, measure the voltage across the fuse holder connections itself. You might find a volt or two, which at 250 amperes of draw would produce about 500 watts of heat. Then if you were to find that your ground point also was hot to the touch, measure with one digital multimeter probe poked into the ground wire and the other probe touching body metal near the ground point. Add that to the amount you measured at the fuse holder.
Here is where the problem begins to accumulate-by adding all of the individual voltage drops, you get the total voltage loss that is subtracted from the battery voltage to result in the actual voltage that the amp has available. Several half and one-volt drops can starve an amp pretty quickly. So the solution for this type of problem is to improve any "hot" connections to feed the amp with the maximum possible voltage.