Performing An RMC Calibration

Reference - RMC™ Room Mode Correction/

the speakers at the mix position and automatically applies corrective ﬁlters to dramatically minimize low frequency resonances. Because room modes create resonance at speciﬁc frequencies with very narrow bandwidths (sometimes called “Q”), the on-board analyzer has the intelligence to identify the speciﬁc frequency and Q and apply a corrective parametric ﬁlter to only the component of the signal that excites the problem. The LSR4300 RMC system can place a parametric ﬁlter at 73 frequencies (1/24th octave centers) between 20 Hz and 160 Hz, with a variable Q from 1 (1-2/5 octave bandwidth) to 16 (1/11 octave bandwidth), with 3 to 12 dB of attenuation.

When the calibration mic is connected and the RMC analysis is initiated with the press of a single button, the LSR4300’s onboard computer emits a reference tone that is measured at the mix position using the supplied calibration microphone. The computer measures the response received via the microphone and compares it with the original tone being emitted. It determines which if any conditions should be corrected, and then calculates and applies a corrective ﬁlter. The entire process takes only a few seconds per speaker.

During the RMC calibration process, the computer trims speaker levels in ﬁne 0.25 dB increments so that all speakers in the system produce equal SPL (sound pressure level) at the mix position. This feature is particularly useful in surround sound applications where space limitations often prevent optimum speaker placement. For example, if the center speaker is closer to the mix position than the other main speakers, attenuation must be applied so your mix balances are correct. Without this correction, your end product will sound unbalanced on a properly calibrated playback system.

To get the beneﬁt of JBL’s revolutionary RMC technology, RMC calibration should be performed The RMC calibration process is simple and easy, taking only a few moments to complete. RMC settings remain in memory even after the speakers are powered down, so typically the process only needs to be performed one time. RMC calibration should be performed:

•The ﬁrst time you use your LSR4300 monitors. (The front panel RMC button will be lit to remind you of that).

•When the LSR4300 monitors are relocated, repositioned, or moved into a different listening space (either a different room altogether or a different area within the same room).

•After any kind of change to the room’s acoustic treatment (such as adding carpeting, bass traps, or other kinds of diffusers).

•When there is a signiﬁcant change to the room’s furnishings (such as adding a console enclosure, a sofa, or other large piece of furniture).

RMC settings created in a prior environment are not relevant to the new environment.

If you do not wish to recalibrate the LSR4300 system after repositioning or moving one or more speakers, press the RMC switch to bypass the existing settings.