AudioControl FOUR.1i

In-Dash Car Audio Equalizer with Auxiliary Input & 5-year warranty*!

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For over two decades, AudioControl has been designing and manufacturing award-winning autosound products at our factory located in the rainforests of the Pacific Northwest. During this period, countless sound-off winning contestants have chosen AudioControl products to give them the competitive edge. "Can you really win without AudioControl", was part of an article written commenting on competition winning systems. Nothing sounds better than an awesome recording played back on a kickbutt system. Unfortunately, the acoustics of your vehicle can take away from your systems performance. While AudioControl products do not change the laws of physics (although they act like they do), autosound enthusiasts have long known that AudioControl products "make good stereo sound better"

FOUR.1i - In-dash Equalizer with Aux Inputs

If your performance car audio system is designed for maximum sound quality and maximum control, then the FOUR.1i is the car audio processor for you. Designed to be the world's first professional quality in-dash equalizer, the FOUR.1i boasts such features as 13 volt signal capabilities, a master volume control, and auxiliary inputs for secondary sources. In addition, five equalization controls give just the right amount of control for the user. AudioControl's line of in-dash car processors offer features and functions that allow you to adjust and tweak your performance car audio system from the convenience of the driver seat. Included are features like equalization, electronic crossovers, master volume control, and high voltage line drivers.

Key Features:

Graphic Stereo Equalization:

The FOUR.1i turns the dashboard of your car into a mini-mixing board, just like those in a recording studio. The FOUR.1i has four frequency controls set at 8000Hz, 2000Hz, 500Hz, and 125Hz. These controls will make dramatic improvements in any system.


You want bass, we've got bass. This specially designed parametric control lets you adapt the bass response of any system to your listening desire. Given all of the various types of music combined with numerous possible bass response anomalies in every vehicle, a single equalization control for bass just doesn't cut it. It's like painting a picture with only one color . . . BORING!

Pre-Amp Line Driver:

Talk about your ironies. To operate with maximum dynamic range and the best signalto-noise ratio amplifiers require a high voltage input signal (generally 2 to 5 volts) . On the other hand, typical source units only put out 1 to 2 volts, (if you're lucky!) In a system where the source unit is located in the front of the car and the amplifiers are located in the rear, the length of the connecting cables will also cut the strength of the signal. The FOUR.1i includes a line driver that takes the weak output voltage of a head unit and increases it up to 20dB (up to 13 volts peak) and then delivers it downstream to the amplifier inputs.

Auxiliary Input:

The FOUR.1i has an "AUX" switch on the front to allow you to switch back and forth between sources. If you are thinking about adding a video system, or even that extra compact disc player or DVD player, the FOUR.1i makes hook-up a snap!

Balanced Inputs & Outputs:

The FOUR.1i uses a unique balanced differential input circuit that helps cancel any noise that radiates into the signal path between the source unit and your FOUR.1i. The FOUR.1i then sends this balanced signal downstream to another processor or amplifier that has balanced inputs (blatant plug for AudioControl products) which will keep it noise-free.

General Features:

  • Stereo Graphic Equalization
  • Switchable Backlighting Color (Amber/Green)
  • Para-BASS Low Frequency Controls
  • Pre-amp Gain: 20 dB
  • Line Driver: 13V Peak Output
  • Balanced Differential Inputs and Outputs
  • High-Headroom PWM Switching Power Supply
  • Main and Auxiliary Switchable Inputs
  • Master Volume and Fader Control
  • Selectable Ground Isolation
  • Optimum Voltage LED
  • Weight: 2 lbs
  • Size: 1.00" H x 6.75" W x 5.00 "D
  • Authorized Internet Dealer
  • 5 Year Manufacturer's Warranty (*when installed by an authorized AudioControl dealer)

FOUR.1i Specifications

  • Maximum input/output level: 9.5Vrms/13V peak
  • Frequency response: 10 - 100,000 Hz; ±1dB
  • Total harmonic distortion: 0.005%
  • Signal to Noise ratio: -110dB
  • Input Impedance: 20Kohms
  • Output Impedance: 150ohms
  • Input gain: 20dB
  • Inputs: Switchable 2 source, 2-channel
  • Balanced inputs: Yes (switchable)
  • Balanced Outputs: Yes (switchable)
  • Output ground isolation jumpers: Yes
  • Equalization Cut/Boost: ±12dB
  • Power supply: High-headroom PWM switching
  • Power draw: 250mA
  • Recommended fuse rating: 1 Amp
  • Illumination Color: switchable green or amber
  • Country of origin: U.S.A

Check out the AudioControl FOUR1i Owner's Manual

Equalizer Specifications

Type of Equalizer
This determines the way the equalizer processes the signal from the source unit. A parametric equalizer allows to you adjust the center point of the frequency band you are adjusting as well the bandwidth which can be narrowed or widened. A graphic equalizer has fixed frequency bands and bandwidth and only the frequency bands can be adjusted. A digital equalizer uses a software program to tune your system.
A graphic equalizer typically has more adjustable bands and is less expensive, whereas a parametric will have fewer bands but offer a greater level of control and provide more tuning options. Digital equalizers will tune your system with the most detail and precision but require a computer and are typically a little higher in price.
Equalizer Bands
The number of graphic or parametric equalizer bands the receiver has. The better the EQ, the more likely you will be able to "tweak" your sounds to your desire.
4 band + Para-BASS
Equalizer Frequencies
The frequency range that allows control of the center frequency of each equalization band.
40 - 8000 Hz
Built-in Crossover

A crossover is a type of filtering system that permits only certain frequencies to play. A Low-Pass (LP) crossover allows only frequencies below its setting to get through which is good in the case of some subwoofers. A High-Pass(HP) filter allows frequencies above its setting to pass through, this is normally used on speakers.

When a crossover is set to FULL it means no filtering is added and the full frequency spectrum is allowed through the amplifier. Filtering is important because feeding a speaker frequencies it cannot reproduce effectively creates distortion.

Built-in Bass Reconstruction
Bass reconstructors, or bass enhancers, improve low frequency reproduction in a car audio system with at least one subwoofer. These bass expander products will help your subs produce accurate bass thumps.
Line Driver
A line driver is a small amplifier used to support the strength of the audio signal coming from the source unit.
Speaker Level Inputs
Speaker level inputs are commonly referred to as high-level inputs and vice versa. This input type allows you to get your audio signal directly from the speaker wire in your vehicle, instead of using RCA cables. The advantage of this is factory integration, as most stock radios do not have RCA outputs to run amplifiers.
Total Number of Inputs
This is the total number of input connections that go into the unit.
Total Number of Outputs
This is the total number of output connections that the unit will produce.
Button Color
Refers to the color of the physical buttons on the unit.
2 User Selectable Colors (Green/Amber)
Signal Boost/Cut
The available signal boost or cut for each of the frequency bands.
12 dB
Max Output Level
The maximum level (in volts) of signal output. A higher level will increase the clarity and boost your signal.
Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). Bigger is better, meaning the wider the range, the better. The optimal range is 20 - 20,000 Hz (which is the range of human hearing).
10 - 100,000 Hz
THD (Total Harmonic Distortion)
The amount of change in harmonic content of the signal as it is amplified. A lower figure indicates less change and a more accurate amp. THD below 0.10% is inaudible.
Signal-to-Noise Ratio
This spec compares the strength of the signal to the level of background noise. A higher value indicates less background noise.
-110 dB
The width of the item from left to right (side-to-side) measured in inches.
The height of the item, measured from top to bottom, in inches.
The front-to-rear depth of the item, in inches. If the item is angled or slanted, this value is the bottom measurement.

Warranty and Return Policy

Parts Warranty Duration
5 years
Labor Warranty Duration
5 years
Warranty Provider

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
4 Star
3 Star
2 Star
1 Star

Average Attribution Rating


Long Island City, NY

audio in control

May 31, 2010

this product will enhance any system 1000%. Best EQ I ever used, clean sound, and hard hitting very well made, KUDOS to Sonic.

21 of 25 found this helpful

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Brookings, Or

Moderate Value

August 10, 2010

I bought this for the wife's car, hooked-up to the factory deck, and a JL 5/500 amp. I wanted her to have some equalizer capability and a way to connect her iPod. Works as stated and integrates into the system as planned.

19 of 23 found this helpful

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New Zealand

Verified Purchase
Preamp with Aux -in

October 1, 2016

This is a great product from AudioControl, 24/192 Audio from my Computer to my D/A converter, then to AudioControl's Aux-in with Preamp-outs. Then Going to amplifiers. Such a neat device.

0 of 0 found this helpful

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Accessory Tools and Products

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V-Series: 0.5m (1.64 ft) 2-Channel RCA Audio Interconnect Cable

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V-Series: 3m (9.84 ft) 2-Channel RCA Audio Interconnect Cable

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X-Series: 3m (9.84 ft) 2-Channel RCA Audio Interconnect Cable

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V-Series: 3m (9.84 ft) 4-Channel RCA Audio Interconnect Cable

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NVX XIX43 X-Series 4-Channel RCA Audio Interconnect Cable

X-Series: 3m (9.84 ft) 4-Channel RCA Audio Interconnect Cable

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Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: AudioControl FOUR.1i

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AudioControl FOUR.1i

In-Dash Car Audio Equalizer with Auxiliary Input & 5-year warranty*!


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