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__What years where the XS series amplifiers produced?

1997 - Current

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__Are the XS series amplifiers stable to 2 ohms bridged?

Yes, but there are a couple of things you MUST consider when running an XS
amp at 2 ohms bridged. The amplifier must have a steady supply of current from
the car's electrical system so you'll want to run a minimum of 4 gauge power
cable from front to rear. If the main cable run is longer than about 10 feet
(most are), then you'll want to step up to 2 gauge. A capacitor is HIGHLY
recommended for 2 ohm bridged operation. The capacitor should have at least 1
farad of capacitance. The only other consideration is heat. With more power
comes more heat so you may have to have some form of cooling fan system to
prevent thermal shut down.

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__How much power does an XS series amplifier
provide at 2 ohms bridged?

The continuous power at 2 ohms or 1 ohm bridged remains about the same.

When designing the XS series amps, we wanted a design that made its best power at normal loads. By normal, we mean 4 ohms bridged. We know that no matter what we say, or how loud we say it - People will still hook the amp up to lower impedances trying to get more power. So, our number one goal is that the amp continue to operate at lower impedances. The only way to do that is to limit the continuous power output of the amp when it's hooked up to lower impedances. Here's why -

Wattage is equal to voltage times current. Running the amp at 2 ohms bridged means more output current. Current makes heat. We can't allow the amp to make more heat than the heatsink can reasonably dissipate. With the addition of cooling fans, the heatsink can manage a more heat than what's generated from a 4 ohm bridged load so there's some room for a bit more power. Here's how we limit the power increase to what's manageable:

The XS series amps have a circuit that detects the amount of current leaving the speaker terminals. If the current is high enough, AND lasts long enough (longer than 50 milliseconds), the circuit limits the amount of voltage that the power supply can produce. This in turn limits the power output of the amp. So continuous power output remains about the same with the power composed of more current and less voltage.

There is a bright side to all this. Remember I said that the excess current demand had to last longer than 50ms. The dynamic peaks in most music last less than 20ms. Therefore, the circuit never has a chance to affect the power supply voltage for musical peaks. All this means that the amp is allowed to make more power with musical peaks while continuous power remains about the same. You could say that the "headroom" of the amp is increased.

If you have to run the amp 2 ohms bridged, you can. Just understand that you
must follow the above suggestions to make sure your amplifier isn't damaged or
not operating correctly. I wouldn't recommend running it 1 ohm bridged. The amp will shut down (red LED) if the output current gets too high (looks like a shorted speaker).