Revel LFO - Manual (Page 9)

9 LFO Programming Software
User Guide
Recommended Test Microphones:
» AudioTools iTest mic. This microphone requires no additional hardware.
» AudioControl CM-20, CM-125 or CM-145 or Josephson C-550H (available at http://www.audiocontrol.com/t37/62294/Standard.html )
» Behringer ECM8000 (see http://www.behringer.com/EN/Products/ECM8000.aspx ).
The Audio Control, Josephson and Behringer microphones require the additional purchase of the AudioTools IAudioInterface2 box, a microphone stand (for
precise and consistent mic positioning) and an XLR-terminated microphone cable.
Alternative Audio Measurement Systems
If you choose to use an audio measurement system other than AudioTools, to ensure properly precise measurements it must have the following features
and capabilities:
• An RTA function with at least 24 th -octave resolution or FFT function with at least 16k resolution
• A high-quality measurement microphone and input circuitry
• The ability to output measurement data in standard text format
• The ability to do spatial averaging
Test Noise Requirements:
In addition to the measurement hardware described above, you will also need the test noise CD audio fi le that was included as part of the LFO software
download. Locate the test noise audio fi le (named "Measurement Stimulus Correlated Pink Noise –20dB"). You need to be able to play this CD on your
audio system, either through a disc player in the system (in which case you will need to burn the audio fi le onto an audio CD), or through your computer,
which will need to be connected to your audio system via a digital connection (HDMI, coaxial or TOS-link).
MEASURING A SURROUND-SOUND SYSTEM'S LOW-FREQUENCY RESPONSE IN
YOUR LISTENING ROOM
NOTE: These instructions explain how to measure and equalize a multi-channel surround-sound system. For instructions on how measure and
equalize a two-channel audio system, please see Measuring a Two-Channel System's Low-Frequency Response in Your Listening Room, on page 25..
The Revel LFO software is extremely sophisticated and fl exible, and can be used in several different ways. How you use it will depend on the confi guration
of your audio system, how "hands-on" you're willing to get and how accurate you want the results to be.
SPATIAL AVERAGING
The most accurate measurement results will be obtained by using a spatial average of several measurements made with the measurement microphone
(mic) at several different listening locations in the seating area. If your test/measurement system allows for spatially-averaged measurements you should
do so.
If your test/measurement system does not allow for spatially-averaged measurements you will need to perform a single measurement with the mic placed
only at the Primary Listening Position (PLP), but the results will be less than optimal, even at that single listening location. The procedures in this section
describe how to measure using a spatial average.
BEFORE YOU BEGIN, PLEASE NOTE THE FOLLOWING.
• If your system processor's bass management crossover has adjustments for crossover frequency and slope, set it to an 80Hz crossover frequency and
4th-order low-pass and high-pass slopes. If your processor can automatically set the crossover frequency and slope, you must disable this function.
• If your system's processor has a built-in equalization function, perform it before you attempt to measure or equalize your system.
• Set the Power Mode switches on all subwoofers to the "On" position.
• Make sure that the test noise only plays through your system's subwoofer(s). If your system has a separate processor and power amplifi er(s), turn the
power amplifi ers off. If your system has an AVR you may have to go into its speaker setup menu and temporarily set the system up as if it has only left
and right front speakers. Then you will need to disconnect one of the speaker wire conductors each from the left and right front speakers.
CAUTION: Make sure that the loose conductor does not come in contact with the other conductor or with anything else on the speaker. Touching
conductors can create a short-circuit that can damage your amplifi er.