SubWoofer Set up and Optimization

One of the challenges to a proper subwoofer setup is subwoofer placement or subwoofer location. People often want to point at their subwoofer location and say, “there it is,” but the proper way on how to setup a subwoofer is to place the subwoofer in the right location within a room.

Step 1 – Subwoofer placement

Begin with a Subwoofer location at an odd number partition such as 1/3rd or 1/5th of the length of the wall opposite of the main listening position and opposite major openings such as doors and windows.

Step 2 – Subwoofer setup – Wire Connections

Connect your processor or surround sound receiver to your subwoofer. Keep your cables loose because you’re going to be moving the subwoofer around.  There will be as many as 3 three main connection possibilities. They are:

The LFE signal, the two channel left or right input or both. LFE can be confusing to people because they tend to use it as a primary connection for most sub-woofer setups. LFE stands for low frequency effects channel; it’s the independently recorded effects channel that movie producers will use to produce dynamics special effects. In music there is no such channel by using the preamp left right outputs on the back of your receiver you’ll be able to pass that base information that’s naturally in your stereo channels to your sub-woofer.

If you’re using an LFE audio connection in a home theater setup there’s an easy sound check to determine if the processor is sending a signal for a two channel use.  Simply play a two channel recording to listen if any sound comes from the sub-woofer. If the sub-woofer does create sound you don’t have to connect the left and right line inputs

Adjusting your Subwoofer or Surround Sound Receiver Settings.

If there isn’t base coming from your subwoofer while listening to the two channel audio then you either need adjust the settings in your receiver or you’ll need to connect the left and right stereo connection from the receiver to the input on the subwoofer.

If you’re using the speakers as part of only a two channel set up and not as part of the surround sound system you can connect using the left and right line
outputs on your receiver to the line inputs on your subwoofer.

Step 3 – Setting the Sub-Woofer or AVR Control Controls

Set your controls to their initial settings. Your level should be set to 4, phase should be set to 90.° Set the low pass filter to 70% of your main speakers low-frequency extension. For example, if your front speakers are rated down the 50 Hz set it to 35 Hz. If your sub-woofer has a level adjustment knob it’ll have values like 25 Hz or 50 Hz or some other adjustment, set these to zero.

Step 4

Setup the subwoofer placement where you would normally be listening, then playback a recording. Crawl around and listen to the bass response in different places where you will often listen. Listen for multiple bass frequencies where you get all the notes right. Once you find that sweet spot move the sub-woofer to that spot. And now, take a listen from the main listening position just to double check your subwoofer location.

Step 5 – Tweek the Controls

For Left and Right inputs you want to listen to a two channel recording. For the LFE input listen to the sounds from a familiar audio track DVD or Blu-ray.

If you have the left or right line inputs connected you’ll set the low pass filter first. While you listen have an assistant start turning the low pass knob up until the sound starts pulling into the sub. Then back it off to the proper setting.

Now for speakers connected to an LFE you’re going to set the controls in your processor console. Your receiver’s manual will tell you how to access these setting. If you have both LFE and left and right inputs, set your system to large for main and both or ultra for subwoofer mode. This will allow two channel bass to go out to the right left connections and LEF to the LFE output. if you’re using smaller speakers that can only handle bass below 80 Hz set them for small. LEF will be the only cable needed.  Set  cross-over 70 Hz, high past 12 dB, low pass 24 dB. If you are using a wireless subwoofer, add 14 feet for the distance to adjust for latency. Adjust settings so the bass sounds like it’s coming from the speakers and not the subwoofer.

Phase Adjustments

Now for all setups you will adjust the phase play. Listen to a 2 channel recording with lots of bass and rock the phase control between zero and 90°.  Choose the setting that creates the best blending between the speakers and subwoofer.

Level Adjustment

If you’re subwoofer has a level adjustment knob labeled 25 Hz or 50 Hz use the same recording and set the knob down the -10 dB and listen. Then go up to +10db and listen. Rotate back and forth, closer and closer to zero stopping at each level until you find your favorite. Finally you’re going to set the level for subwoofer. With the two channel recording still playing increase the level until you can hear the bass coming from the subwoofer itself rather than it sounds like it’s coming from the main speakers. Then back it off just enough so the bass sounds like it’s coming from the main speakers.

Surround Sound Receiver Adjustments

If you are using LFE connection you will want to set level in your surround sound receiver as well. Leave the level control for the subwoofer the same. And adjust the level in the surround sound receiver the same way. You might want to set the LFE output a little bit higher.