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Helix SPXL1000

Competition Series mono subwoofer amplifier — 1750 watts RMS x 1 at 1 ohm

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Item #: 975SPXL1KB

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An amp that means business

Helix created the Competition SPXL1000 amplifier for those of you who want an amp with massive power and uncompromised sonic fidelity. This mono workhorse can deliver 750 watts RMS to a 4-ohm sub or 1200 watts RMS to a 2-ohm sub, and can even blast out 1750 watts RMS to a 1-ohm sub or subwoofer system. SPL competitors, you can even gang two SPXL1000 amps together to bring a whopping 3500 watts RMS to the party.

Extraordinary features

Gold-plated connections won't tarnish or suffer any oxide buildup that could interfere with the signal flowing in or out of this amplifier. You can adjust the low-pass filter, tunable bass boost, and variable phase control to tune your subwoofer system for maximum performance. For the SPXL1000's input, you can choose between using a single mono signal or a Real Mixed Input, which uses preamp mixing to properly combine the stereo left and right channel signals, instead of the usual Y-cord-type wiring.

Product Highlights:

  • mono subwoofer amplifier
  • 750 watts RMS x 1 at 4 ohms (1200 watts RMS x 1 at 2 ohms)
  • 1750 watts RMS x 1 at 1 ohm
  • Class D design
  • 24-karat gold-plated RCA input, power, and speaker connections
  • double-sided copper plated circuit boards
  • noise-free inputs
  • stereo or mono inputs with Real Mixed Input option
  • can be ganged with a second SPXL1000B for double the power
  • variable low-pass filter (35-250 Hz)
  • bass boost (0-18 dB from 40-120 Hz )
  • continuous phase adjustment: 0 to 180 degrees
  • wired remote bass level control included
  • preamp inputs and outputs
  • 2- or 4-gauge power and ground leads and a 150- to 160-amp fuse recommended — wiring and hardware not included with amplifier
  • fuse rating: 80A x 2
  • 20"W x 2-1/4"H x 10-15/16"D
  • warranty: 2 years
  • Our 60-day money-back guarantee

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Helix SPXL1000 Reviews

Hands-on research

What's in the box?

Download owner's manual

  • Mono subwoofer amplifier
  • Two 80 amp maxi-blade fuses (installed)
  • Wired remote control
  • 16.5' Remote cable (RJ-25 plug on both ends)
  • 12" Protect Bridge jumper
  • Six 3/4" Self-tapping screws
  • 5mm Allen wrench
  • 2.5mm Allen wrench
  • Instruction manual (German/ English)
  • Master/Slave wiring instructions

Product Research



1-Ohm Stable: The SPXL1000 is stable down to 1-ohm. The 1-ohm output is 1750 watts RMS x 1 channel; the 2-ohm output is 1200 watts RMS x 1 channel.

Protection Circuitry: The amplifier offers three protection circuits: short circuit (or too low an impedance on the outputs), thermal overload (overheating), and incorrect voltage.

Multiple Amplifiers: Two identical SPXL1000 Competition amplifiers can be strapped together to double the power to a single subwoofer. When used in this configuration one amp is the master (controls gain, crossover point, and bass boost), the other is the slave, and the minimum subwoofer impedance is 2 ohms. The signal is transferred from the master to the slave via a single RCA cable.

Wired Remote: The amplifier includes a wired remote control, offering control of the bass output within easy reach of the driver. The remote has a rotary knob and comes with mounting screws and a 16.5' connector cable (with RJ-25 phone plugs on each end). The remote's approximate dimensions are:

  • Width: 1-13/16" (2-5/8" including the mounting tabs)
  • Height: 1-3/8"
  • Depth: 2-3/16" (2-5/8" including the knob and wiring)


Gain: The rotary gain control is continuously variable from 0.2 volts to 6.0 volts to match the source signal.

Bass Boost: the bass boost circuit has adjustable gain and center frequency (frequency at which the bass adjustment is centered):

  • Gain: rotary dial; continuously variable from 0 to 18 dB
  • Frequency: rotary dial; continuously variable from 40 to 120 Hz

Crossover: The built-in low pass crossover is always active. The crossover point is continuously variable from 35 to 250 Hz.

Phase: The subwoofer phase is continuously variable from 0° to 180°.

Master/Slave: Choose the master or slave mode if using two SPXL1000 amplifiers together to power one subwoofer. The master setting is used when not strapping two amps together.


Power: The power and ground inputs are set-screw terminals; they will accept bare wire up to 2-gauge (HELIX recommends 4-gauge minimum) and are tightened/loosened with the included 5mm Allen wrench.

Note: The amplifier is protected by two 80-amp fuses (160 amps total), but the amplifier wiring kits in the accessory list include 150-amp fuses, and a larger compatible fuse is not available. Optimally a different fuse holder and a 200-amp fuse can be added, or the wire, fuse holder, and fuse can be purchased separately. As a practical matter, however, using the 150-amp fuse included with a wiring kit is unlikely to present a problem.

Remote: The remote turn-on input is a set screw terminal; it will accept bare wire up to 8-gauge and is tightened/loosened with the included 2.5mm Allen wrench.

Speaker Outputs: There are two pair of set-screw speaker terminals, internally wired in parallel so you can easily connect two subwoofers. The terminals accept bare wire up to 8-gauge and are tightened/loosened with the supplied 2.5mm Allen wrench.

Line Input: A pair of gold plated stereo RCA jacks connect to the output signal from the head unit.

Line Output: Stereo RCA output jacks make adding another amplifier easy. The RCA outputs are full range and the setting on the SPLX1000's built-in crossover have no effect on them.

Wired Remote: The cable for the included wired remote control plugs into the RJ-25 Remote jack.

Master Output/Slave Input: A single RCA jack acts as an output or an input (depending on the position of the Master/Slave switch) when two SPLX1000 amplifiers are strapped together to power one subwoofer.

Fuses: The amp is protected by two 80-amp maxi blade fuses.

Protect Bridge: When using two amplifiers in a master/slave configuration and reproducing a 60 to 80 Hz test tone in an SPL competition, the protection circuit can be disabled by connecting the Protect Bridge jacks using the included jumper wire.

Note: The protection circuit should never be disabled when playing music.

Our Product Research Team

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