External bass controls (EBC), or remote bass controls (RBC), are a convenient and easy to install accessory that allows you to tune the bass in your music song by song. For example, if you listen to a wide variety of music, you may want more bass when listening to Rap or Hip Hop and less bass when listening to Country or Heavy Metal. An external bass controller (EBC) will allow you to adjust the bass level without having to pull over and adjust the gain setting on the amplifier.
However, a common misconception about EBC’s is that they are volume knobs for your subwoofers. It’s important that you understand what this little knob is actually doing to your audio signal.
But if you want to be able to tune your music on the fly, an EBC is the way to go. If an EBC is connected to your amplifier, you are essentially bypassing the gain control inside the amplifier and running a wire to the external control known as the EBC. A remote subwoofer control, remote gain control, remote bass control, or whatever you want to call it is actually a remotely located, external gain control.
That’s right! So before you start cranking the knob all the way to the right, understand that you are tweaking the audio signal that you are sending to your subwoofers and turning up the gain too much can cause clipping and ultimately distortion.
If your subwoofers are distorting, you may have the input sensitivity (gain) on your amplifier set incorrectly. Distortion is caused when a soundwave has its amplitude adjusted from a traditional sine wave (round peaks) to a square soundwave (square peaks). Square waves are caused when the input sensitivity (gain) is set in excess of the output voltage of the source unit (ie. radio) and the volume is turned up louder than when the amplifier was set. This "amplified" signal results in square soundwaves that you hear as distortion. You can use an oscilloscope to check the output wave if you have one available or, a more common way is to use a multimeter and measure the output voltage of the amplifier at the speaker terminal and then use this calculation to determine if your gain is set correctly. Voltage equals the square root of RMS Power times Resistance (V= √PxR). For example if you have a 1000W RMS (P=Power) amplifier connected to a 2Ω (R=Resistance) subwoofer, the optimum voltage would be 44.72V (volts). You can adjust the gain up or down while measuring the voltage until the multimeter measures that voltage and your amplifier would be properly set and the distortion should be eliminated. Check out our YouTube video on How to Set Your Amplifier Gain Using Ohm’s Law and if you need test tones to set your amplifier gain, visit https://www.mtx.com/testtones to download.
Although the EBC is essentially a remotely located gain control, it is still important that you still set the internal gains on the amplifier first. In most cases, the EBC will not increase the internal gain setting thus protecting your system from square waves and distortion. Set your gains for maximum bass levels and use your EBC to reduce the amount of bass when desired.
Once you have set your gain on the amplifier accordingly, you are ready to install your EBC. Wiring of the EBC varies depending on the model of amplifier and type of connection available for an EBC. Choose a location for the knob that is out of the way yet easy to access. Common installation locations include unused dash locations, inside the center console, or on the trim panel below the steering wheel. Some models can be flush mounted with only the knob showing and others are intended to be surface mounted with the whole box visible.
Flush mount in center console
Flush mount on dash panel
Surface mount in center console
There are multiple types of external / remote bass controls on the market. Most of them are mechanically the same thing but might look a little different cosmetically. The major difference between various models is how they connect to the amplifier. Different amplifiers may have different types of connections to install the EBC. Some universal bass controls are installed in line with the RCA cables. They have an input and an output. The input comes from the radio / head unit and the output goes to the amplifier. Other brand specific models plug directly into the amplifier.
For MTX Audio amplifiers, there are 6 different external / remote bass control options depending on your MTX amplifier.
Our EBC’s may also work on amplifiers of other brands. Check the type of connection (3.5mm, RJ45, etc…) to the amplifier and match it up accordingly.
So before you go cranking on your EBC knob, make sure you aren’t sending a square wave to your subwoofers. Set your internal amplifier gains first for maximum bass and use your EBC to turn the bass levels down when desired. Distortion doesn’t sound good and square waves could damage your subwoofers.