(Low-Frequency Optimizer) Software User Guide
ABOUT THIS DOCUMENT Your Revel subwoofer contains an ultra high-quality DSP-based signal processor that can maximize the subwoofer's low-frequency performance (and in a 2.x-channel music system, the performance of the main left and right speakers).
Placing Four Subwoofers When installing four subwoofers, place each one in a room corner. In rooms with more than four corners, use the four corners closest to the listening area. Video Screen Placing Two Subwoofers Placement of two subwoofers will be determined by your room’s seating arrangement. For Rooms with a single row of seating, placing the subwoofers in the two front corners will produce the most consistent bass performance throughout a single row of seating.
For rooms with multiple seating rows, placing one subwoofer in a front corner and the other subwoofer in the rear corner on the same side of the room (as shown below) will produce the most consistent bass performance throughout multiple seating rows. from front-to-back. As explained previously, placement of two subs in the front corners will still improve bass performance consistency from side-to-side.
When using only a single subwoofer we strongly suggest performing the measurements described in Measuring a Surround-Sound System's LowFrequency Response In Your Listening Room, on page 8, with the subwoofer in each of the room’s corners to find the corner that produces the most consistent results at the various listening positions in your room.. Since wall construction is almost never perfectly identical on opposite walls, common formulas such as placing subwoofers at 1/4 points rarely work in practice.
Adjustment Tabs (shown with System Tab active) Menu Tabs Frequency-Response Display Window Connection Status Indicator Frequency-Response Plot Control Adjustments Frequency-Response Curve Display Tabs Fixed EQ Control Mute Buttons Crossover Controls Auto Sense Control Delay Units Adjustment Subwoofer Standalone/ Daisy-Chain Selector Frequency-response display window; This window provides graphic display of selected frequency-response curves for comparison and adjustment.
Adjustment Tabs (shown with System Tab active) Menu Tabs Frequency-Response Display Window Connection Status Indicator Frequency-Response Plot Control Adjustments Frequency-Response Curve Display Tabs Fixed EQ Control Mute Buttons Crossover Controls Auto Sense Control Delay Units Adjustment Subwoofer Standalone/ Daisy-Chain Selector Subwoofer System controls: When the "System" adjustment tab is active the following controls are available for the connected subwoofer: NOTE: The Subwoofer System contr
CONNECTING YOUR COMPUTER TO YOUR REVEL SUBWOOFER Once you’ve installed the Revel LFO software in your computer you must establish a control connection between your computer and your Revel subwoofer(s). 1. Turn the subwoofer's Power switch to "On." (The Power LED will glow green.) 2. Connect the computer to the subwoofer's USB port using a USB cable.
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).
• Select the Subwoofer Tab. The subwoofer adjustment screen will appear (see illustration below). Subwoofer Tab Subwoofer Level User-Adjustable Control Subwoofer Level Adjustment Subwoofer Delay Adjustment Subwoofer Polarity Adjustment • Ensure that the Subwoofer level User-Adjustable control is not selectd (no check-mark).
SETTING UP AUDIOTOOLS NOTE: If you're using a different audio measurement system, go through its setup procedure at this time. 1. Launch AudioTools on your iOS device. The main menu screen will appear. 2. Tap Settings, then touch General. The General settings window will appear. 3. If you are using the iOS device's built-in microphone, select "Enable" under Mic Compensation Filters. 4. Set your preferred distance units to either feet or meters. 5.
6. Select Acoustics, then select FFT (Fast Fourier Transform). The measurement graph screen will appear. Resolution Button Start/ Pause Button Stop Button Wrench Button Decay Time Button 7. Tap the Wrench button. The FFT Setup window will appear. Make sure all the settings match those shown below, then tap Done: 8. Tap the Resolution button. In the slide-in window that appears, set the resolution to 1/24th-octave then tap the button again. 9. Tap the Decay Time button.
MEASURING YOUR SUBWOOFER(S) 1. Determine the various locations for the measurement microphone. You should optimize the measurements for your room's seating area by taking measurements only within it. (A large seating area will require more measurements.) NOTE: You can weight the results to favor the primary listening position (PLP) by measuring for a longer time in that location than at the other mic positions. 2. Play the test noise through the subwoofer(s).
DETERMINING AND APPLYING CORRECTIVE EQUALIZATION Selecting and importing a Target Response Curve Before you can correct your system's response you need to select a target response curve that you want for your system. Although it would be natural to assume that a totally flat frequency response curve would be the ideal target, perfectly flat frequency response actually sounds quite unnatural.
Exporting Measurement Results into LFO Software Before you can apply corrective equalization you must export your measurement results into the LFO software. The steps below explain how to export the results from AudioTools. (If you are using a different measurement system, follow its exporting instructions.) 1. Make sure your iOS device running AudioTools and your computer running the Revel LFO software are both on same Wi-Fi network and subnet 2. In AudioTools, tap the Stop button.
7. In the LFO interface window, select the Import Curve tab. The Import Curve dialog box will appear. 8. Make sure that the Curve Type is set to "Measured Results" and the Channel is set to "Subwoofer", then use the Browse function to select the curve you just saved into your computer from AudioTools. 9. Select OK. 10. The LFO interface window will return, with the Frequency Response Display window showing both the Target Response curve and your system's subwoofer Measured Response curve.
11. Use the Position Adjustment control to move the subwoofer Measured Response curve up or down in the display window so its overall shape overlays the shape of the target curve as closely as possible (see illustration for Step 10). 12. If you need to increase the Frequency Response Display's visual resolution to see the curve details, select Plot Control, then decrease the Level (Y) Axis's Max value and increase its Min value.
EQ filter type selector: This control lets you choose the type of EQ filter to employ: • Flat: No EQ is applied. • BSHLF (bass shelving): Bass shelving EQ behaves similar to a conventional bass tone control, boosting or cutting all frequencies below the selected EQ frequency (see illustration below). Only EQ frequency and EQ level adjustments are available.
• PEQ (parametric EQ): As implemented in your Revel subwoofer, parametric EQ provides control of EQ frequency, EQ level and the "Q", (bandwidth) of the EQ adjustment. This equalization type is known as "peaking" (also called band-pass), because it allows you to increase or decrease a relatively narrow band of frequencies that centers on the selected EQ frequency, producing an EQ curve that looks like a mountain peak or valley (see illustration below).
EQ "Q" (quality) and "BW" (bandwidth) selectors: "Q" (quality) and "BW" (bandwidth) are different ways of expressing how broad or narrow a range of frequencies is affected by a PEQ level adjustment. The selectors are interconnected; adjusting the Q will also change the BW, and vice versa. (The Q/ BW selectors are inactive for BSHLF and TSHLF filters.) Increasing the Q/decreasing the BW will narrow the range of frequencies the PEQ adjustment affects (see illustration below).
Equalizing Your Subwoofer We encourage you to experiment and become familiar with how the LFO software's EQ controls operate. You can't hurt anything while making EQ adjustments, so feel free to try different filter combinations even if at first they may seem counter-intuitive. Note that you will mostly be using PEQ (parametric equalization) filters to equalize the subwoofer's frequency response. The broad effect of shelving filters is useful only in certain circumstances.
5. When you are satisfied with the improvement created by EQ1 filter, repeat steps 3 – 4 with EQ2 filter to reduce the next peak in response. Note that the parameters of the two filters may interact, in which case you will have to adjust each more than once to get the area to match the Target Response curve. Area Improved by EQ2 Filter EQ2 Filter 6. Concentrate on the region between 20Hz and 200Hz. Try to make this region correspond to the Target Response curve as closely as is practical.
7. If any of the LFO software's 10 EQ filters remain unused, you can repeat steps 3 – 5 to reduce any deep dips in response that are above 30Hz. NOTE: Using EQ boost for frequencies below 30Hz can quickly exhaust the subwoofer amplifier's power and limit your system's dynamic range. In the example below we've cheated a bit by using the EQ9 filter for a narrow-bandwidth (Q = 12) 6dB EQ peak that reduces the –10dB dip at 25Hz by 6dB. 8.
ADJUSTING SUBWOOFER POLARITY The polarity setting determines if the subwoofer's cone moves towards the room when the subwoofer receives a positive voltage (Normal) or moves away from the room when the subwoofer receives a positive voltage (Inverted).
