JL Audio
LoC-22
Line Output Converter
Overview
Designed by JL Audio Sr. Engineer Bruce Macmillan, the LoC-22 is an active two-channel processor engineered for applications requiring the attenuation of factory audio signals for use with aftermarket amplifiers and signal processors.
The LoC-22 utilizes a fully regulated, switching MOSFET power supply and an all-analog circuit design to deliver flat frequency response, at any signal level (3 Hz – 32 kHz, +0, -1dB), without altering bass response at high levels, like many passive line output converters do.
Engineered to combat induced cable noise, the LoC-22 features a differential-balanced input architecture making it compatible with virtually any analog audio signal. Capable of accepting up to 40V RMS per channel (equivalent to 400W @ 4 ohms), the LoC-22 easily handles the most powerful factory amplifier outputs. An onboard dual-range input load switch allows compatibility with most factory amplifiers that employ impedance sensing to mute channels.
Ideal for full-range or low-frequency applications, the LoC-22 is equipped with a pair of analog RCA-type, line-level output jacks (up to 8V RMS) to feed audio signals to your aftermarket system. Analog outputs are compatible with most types of aftermarket signal processors or amplifiers. Setting output levels is super simple and easy, thanks to a specially calibrated, onboard clipping indicator that works with test tones or music. The LoC-22 offers two automatic turn-on methods (DC-Offset Sensing or Signal Sensing) and provides a positive 12V turn-on output to activate aftermarket amplifiers or other downstream electronics.
The LoC-22 includes the following features:
- Fully active, all analog circuit design by Bruce Macmillan, handles powerful factory amplifier outputs, up to 40 volts per channel
- Differential-balanced input architecture offers noise rejection and compatibility with most analog outputs from OEM source units and amplifiers
- Dual range input load switch (20 kΩ/Normal, 60 Ω/Low Z, thermally protected) for maximum compatibility with OEM amplifiers
- One stereo pair of crystal-clear, line-level RCA output jacks (up to 8V RMS)
- Automatic turn-on via DC-Offset or Signal-Sensing
- A dedicated 12V remote turn-on output (maximum 100 mA) to activate aftermarket signal processors or amplifiers
- Onboard LED clipping indicator makes output level setting quick & easy
- Ultra-compact chassis design fits into just about any installation location!
Differential-Balanced Inputs
JL Audio’s Differential-Balanced Inputs are engineered to combat induced cable noise, which is a common problem in car and marine audio installations. This technology allows for the use of conventional RCA cables, while delivering many of the benefits of a true balanced connection and accepting a wide range of input signal levels.
Today’s vehicles are equipped with sophisticated electronics capable of generating noise and interference that can intrude into the audio path, ruining the listening experience.
Most audio equipment uses single-ended, ground-referenced RCA jacks to receive audio signals. This means that the RCA shield is connected directly to signal ground. This is a simple, cost effective input design that works well for short runs in noise free environments. In noisier environments, this method cannot reject the common mode noise that could be on both RCA conductors (shield and center conductor).
By having more than one chassis-grounded RCA shield on a device, single-ended input designs are also more susceptible to ground loops. If noise is present on both conductors while the shield is connected to ground, the input amplifier will amplify the noise relative to the grounded RCA shield. When there are multiple RCA connections or any other conductors subjected to a magnetic field, this will cause a difference in potential across the RCA loop to be amplified at the grounded RCA as noise (a classic ground loop).
JL Audio’s Differential-Balanced Input circuits measure the center pin of the RCA connection relative to the RCA shield, even when the shield is not connected to ground, and even when the voltages at both conductors are moving relative to ground. Because both the center conductor and the shield see high impedance to ground at the input, a ground loop cannot be formed, as there is no current flow to induce a voltage as noise. This works equally well with differential-balanced, or unbalanced signal sources, making this input architecture compatible with all standard car and marine audio equipment, using standard, unshielded, twisted-pair RCA cables. No special cables are required, unlike the fully balanced connections used in professional audio.
Another benefit of the Differential-Balanced Input design is that it easily accepts low-level and high-level signals from a variety of factory head unit outputs and amplifiers, including single ended “ground referenced” sources, as well as Balanced or Unbalanced “Bridged or BTL” sources. This eliminates the need for Line Output Converters (LOCs) in most installation scenarios.
The obvious question is: “Why don’t all car audio amplifiers use Differential-Balanced Inputs?” The answer is simple: it costs more. Executing a proper differential-balanced input section requires more components and better quality components than a basic single-ended design, so you generally won’t find them on less expensive amplifiers.
Specifications
Physical Specifications
| Brand | JL Audio |
|---|