Redline Monitor is an audio plug-in designed for emulating or mimicking studio monitor speakers when using headphones.

Redline Monitor was built and released in 2009 by 112 dB, an audio software company based in Utrecht, Netherlands. Redline Monitor was initially built by Jules Vleugels and it was one of his last projects before passing away on January 23, 2011^[1]. Picking up where Jules left off, development of Redline Monitor has steadily continued over the years with its latest version being 1.0.8 (released on February 02, 2015^[2]).

Redline Monitor's core purpose is to replace the need for studio monitor speakers by emulating how they act when working with high fidelity headphones. Typically, when mixing with headphones, it is extremely difficult for one to discern proper positioning of sound, as the sound is projected directly into one's ears (and not off the walls of a room). It is in no way meant to be an audio effect tool, but a listening tool.

Redline Monitor features technologies such as filtering, frequency-dependent delaying, mid/side encoding, and reverb to move the perceived audio source more forwards, as opposed to being directly projected into one's ears at 180 degrees.^[3]

Being an audio plug-in, Redline Monitor will work with most sound editing software or digital audio workstations (DAW). Some examples include, but are not limited to: Ableton Live, Logic Pro, Pro Tools, and Steinberg Cubase.

Redline Monitor has three different knobs for adjusting: center, soundstage, and distance ^[4].

The center knob adjusts the phantom center of the sound one is listening to. Specifically, this adjusts the levels of sounds which are panned more towards the left and right channels of headphones or multi-channel sources. Raising this can bring the phantom center more towards the back of one's head. Since perception of sound is not easily defined, this is primarily dependent on the user adjusting it, as their perception of sound and space is entirely unique.

The soundstage control is arguably one of the most important controls. It sets the position of virtual speakers based on their angle of separation (in degrees). This adjusts the wideness of the sound that is perceived and emulates the positioning and rotation of monitor speakers when placed on a desk. For example, setting this knob to 90 degrees, would signify that both the left and right speakers are positioned at 45 degrees on either side of the listener.

The distance setting sets how far away the speakers are from one's ears. Typically studio monitor speakers are within a meter from the listener, so this should be set accordingly. Through use of early reflections, the perceived sound is adjusted to appear as though the distance it has traveled is shorter or longer, depending on the placement of monitor speakers.