About External or Remote Bass Controls MTX Audio

An external bass control (EBC), also called a remote bass control or remote gain control, is a small knob that mounts within reach of the driver and lets you adjust your subwoofer's bass output on the fly. If you listen to a wide variety of music, this is genuinely useful. You might want more bass for hip-hop and less for country or acoustic music, without having to pull over and reach back to the amplifier every time.

MTX remote bass control EBC included with MTX monoblock amplifiers

It's Not a Volume Knob

This is the most common misconception about external bass controls. An EBC is not a volume knob for your subwoofers. It is a remotely located gain control. When connected, it bypasses the internal gain control on the amplifier and replaces it with the external knob. Turning it up too high causes exactly the same problem as setting the internal gain too high: clipping and distortion.

Turning up the EBC too high causes distortion Because the EBC controls gain, cranking it past the correct setting sends a clipped, distorted signal to your subwoofers. Distortion sounds bad and generates excess heat in the voice coil. Set the internal amplifier gain first, then use the EBC to reduce bass when needed — not to add more than the internal gain allows.

Set Your Amplifier Gain First

Before using the EBC, set the internal gain on the amplifier correctly. In most cases the EBC cannot increase the gain beyond the internal setting, which protects your system from over-amplification. Think of the internal gain as the ceiling and the EBC as the control that moves you below it.

Set the internal gain for your maximum desired bass level. Then use the EBC day-to-day to dial it back when the music calls for less. This keeps the signal clean at all times.

Set gain with a multimeter, not by ear Use Ohm's Law to calculate the correct output voltage for your amplifier and subwoofer combination, then set the gain to match using a multimeter. See the amplifier gain setting guide or watch the gain setting video. If you need test tones, download them at mtx.com/testtones.

Recognizing Distortion

If your subwoofers are distorting, the EBC or internal gain may be set too high. Distortion occurs when the gain is set beyond the output voltage of the head unit and the volume is turned up, causing the waveform to clip from a smooth sine wave into a square wave. Square waves are what you hear as distortion, and they push more heat through the voice coil than a clean signal.

Clipped audio waveform showing distortion caused by incorrect gain or EBC setting

A clipped waveform — what happens when gain or EBC is set too high. Clean peaks on the left, clipped square peaks on the right.

You can verify correct gain using a multimeter at the amplifier's speaker terminals. The target output voltage is calculated using Ohm's Law: V = √(P × R). For a 1,000W RMS amplifier connected to a 2Ω subwoofer, the target voltage is 44.72V. Adjust the gain until the multimeter reads that voltage and the signal will be clean.

Installing the EBC

Wiring varies depending on the amplifier model. Once the gain is set on the amplifier, choose a mounting location that is easy to reach from the driver's seat but out of the way. Common locations include:

Center Console

Flush or surface mounted inside the console lid or side panel. Out of sight but within reach.

Dash Panel

Flush mounted in an unused switch blank or trim panel. Clean look, easy access.

Steering Column Trim

Surface mounted on the trim panel below the steering wheel. Convenient for frequent adjustments.

Included with MTX Monoblock Amplifiers

No separate purchase needed

A remote bass control is included in the box with MTX monoblock amplifiers.

Current MTX mono amps across the Terminator, Thunder, RTX, Powersports, and Marine lines include an EBC. There is no need to buy one separately. It is already in the box when your amplifier arrives.

Terminator Thunder RTX Powersports Marine

Frequently Asked Questions

What is an external bass control?

An EBC is a remotely located gain control that mounts within reach of the driver. It lets you adjust bass output without reaching back to the amplifier. It is not a volume knob — it controls the amplifier's input sensitivity and turning it too high causes clipping and distortion.

Is an external bass control the same as a volume knob?

No. An EBC adjusts the amplifier's gain, not the head unit volume. Turning it too high causes the same problems as setting the internal gain too high: clipping, distortion, and potential damage to the voice coil. Always set the internal gain first, then use the EBC to reduce bass when needed.

Do MTX amplifiers include an external bass control?

Yes. A remote bass control is included with MTX monoblock amplifiers across the Terminator, Thunder, RTX, Powersports, and Marine lines. No separate purchase is needed.

Should I turn the EBC all the way up?

No. Set the internal amplifier gain for your maximum desired bass level first. The EBC should be used to reduce bass from that setting when the music calls for less. Turning it past the correct internal gain setting causes clipping and distortion, which damages subwoofers over time.