keithling
Stunt Coordinator
- Joined
- Jul 24, 2009
- Messages
- 92
- Real Name
- Keith Ling
Why doesn’t my subwoofer work? If you have a home theater, you probably were bewildered with the set up. One thing I remember when plugging in my Polk sub PSW505) was the simple RCA connection. Of course, I spent about 25.00 on the cable, but I thought it would be worthwhile to add some decent bass to my system. What I discovered, (and I suspect many reading this also have) was that the sub didn’t work with regular stereo, only DVDs with Dolby Digital. Even several of my 5.1 audio discs (DVD-Audio, SACD, and DTS) didn’t seem to send it much bass. After about six months of frustration, I finally found an article that made sense. It also was a clear indictment against the companies that produce home theater receivers and subwoofers.. You see, the sub manual mentioned the “simplest” connection, and another connection. What it didn’t say is that the simplest connection is not the BEST connection. So what did I do wrong? First of all, I entered my center channel speaker as “large” in my receiver set up. While it is considered large as far as center channel speakers go (two 6 ¼” woofers and 1” dome tweeter), it isn’t large in home theater set up jargon. Unless you are using floor standing speakers with lots of bass for your center channel, choose “small” for your center channel speaker set up. These settings determine where the bass goes. I had my front speakers set as large, because they are very large. What I didn’t originally understand was that “simple” connection made my sub nothing more than a glorified coffee table most of the time I used my receiver. The “Best” connection I should have known, since I am a mobile DJ, that the subwoofer/LFE connection receives signals only when the signal is processed digitally in the receiver, or if it sends a direct analog signal to the LFE (subwoofer) output (playing 5.1 audio discs). So, how do you insure your subwoofer gets fed bass signals all the time?
The "BEST" connection
First of all, disconnect that “simple” RCA connector from your sub to your receiver. Find a better use for it, like drying clothes or jumping rope. Next, go to your receiver setting and make sure that you select “no” or “off” for the subwoofer setting. Finally, make sure your front speaker setting is “large” even if your front speakers are small. Why? This prevents any low frequencies from going to the LFE/subwoofer output instead of to the front speaker outputs. Since you have opted to send all of the low frequencies to the front speaker outputs, there is no need to adjust the crossover frequency in your receiver, unless your sub doesn't have a crossover built in. Now you’ll need to change your front speaker connections. The connections from your receiver should first go to the speaker input connections on your sub. You should then run a connection from your sub speaker outputs to the front speakers. These connections should be made with high quality speaker wire. What does this do? First of all, it insures that the primary bass is fed to the subwoofer. Most subwoofers have a “crossover” control to determine which part of the signal goes to the sub amp and which part is passed on to your front speakers.. The goal here is NOT to maximize bass. The goal is to obtain a smooth, realistic-sounding balance of bass with the rest of the program material. Remember that as you turn the crossover point up, the sub will have to produce more upper bass, and at the same time, the front speakers will produce less upper bass. The ideal crossover setting will be somewhere between 80 and 120 hz if you have large front speakers, and 100 to 250 if you have small front speakers. The best way to start is in the middle with the crossover and volume settings. Adjust your crossover until you reach a point that sounds most natural, using music you are very familiar with. Once you have reached that point, adjust your volume if needed. Too much bass makes the music sound muddy. If the vocals are difficult to understand, and the transients on cymbals, drums, and acoustic instruments are not very clear, it is possible your subwoofer is either too loud, or the crossover setting is too high. If the mix sounds harsh or brittle, you may need to add a bit more sub volume, or raise your crossover point a little. Keep in mind that MOST small subwoofers (less than 12”) will not be able to provide much volume in the lower range, like the kick drum . If you really like full bass, don’t skimp on your subwoofer. Also, keep in mind that you can have two if you really want to rock the house. Why TWO subwoofers? While some use two subs to cover both stereo channels, the truth is, the human ear has very little ability to discern direction from low frequency signals. As sound waves increase in size (for lower frequencies) , the directional cues decrease. The real reasons for using more than one subwoofer are as follows: A. Increasing available bass output – In smaller rooms, one decent subwoofer should suffice at low to moderate volume levels. At louder levels or in larger rooms, the requirement for more bass volume increases proportionately. Two subs can provide this increase without distorting either sub. B. Increase dynamic range –some situations, liker bass-heavy Rap, or depth Charges or a heavy T-Rex stomp, require much greater instantaneous output than one sub can provide. C. Better low-midrange separation – While you won’t be able to hear left to right Panning of bass, you will be able to hear bass on both sides of the room. Spreading Out the bass provides a more natural listening experience. Why have a LFE output at all? Honestly, the “point one” in 5.1 mixes was originally intended to feed a speaker capable of producing low frequency effects in theaters. It was not developed to make music sound better, even though it can have that effect with Dolby Digital program material that properly utilize the LFE channel . The LFE channel was developed to simplify the wiring of a home theater. While it can be very effective in movies, it also can drain the life out of your favorite music. If you use the setting above, you should not need the LFE channel at all. When you turn the subwoofer setting to “no” or “off”, the signal that would have gone to the LFE is sent to your front left/right speakers. That signal will now be captured by your sub(s), allowing you to make the most your home theater speaker setup. Happy booming!
The "BEST" connection
First of all, disconnect that “simple” RCA connector from your sub to your receiver. Find a better use for it, like drying clothes or jumping rope. Next, go to your receiver setting and make sure that you select “no” or “off” for the subwoofer setting. Finally, make sure your front speaker setting is “large” even if your front speakers are small. Why? This prevents any low frequencies from going to the LFE/subwoofer output instead of to the front speaker outputs. Since you have opted to send all of the low frequencies to the front speaker outputs, there is no need to adjust the crossover frequency in your receiver, unless your sub doesn't have a crossover built in. Now you’ll need to change your front speaker connections. The connections from your receiver should first go to the speaker input connections on your sub. You should then run a connection from your sub speaker outputs to the front speakers. These connections should be made with high quality speaker wire. What does this do? First of all, it insures that the primary bass is fed to the subwoofer. Most subwoofers have a “crossover” control to determine which part of the signal goes to the sub amp and which part is passed on to your front speakers.. The goal here is NOT to maximize bass. The goal is to obtain a smooth, realistic-sounding balance of bass with the rest of the program material. Remember that as you turn the crossover point up, the sub will have to produce more upper bass, and at the same time, the front speakers will produce less upper bass. The ideal crossover setting will be somewhere between 80 and 120 hz if you have large front speakers, and 100 to 250 if you have small front speakers. The best way to start is in the middle with the crossover and volume settings. Adjust your crossover until you reach a point that sounds most natural, using music you are very familiar with. Once you have reached that point, adjust your volume if needed. Too much bass makes the music sound muddy. If the vocals are difficult to understand, and the transients on cymbals, drums, and acoustic instruments are not very clear, it is possible your subwoofer is either too loud, or the crossover setting is too high. If the mix sounds harsh or brittle, you may need to add a bit more sub volume, or raise your crossover point a little. Keep in mind that MOST small subwoofers (less than 12”) will not be able to provide much volume in the lower range, like the kick drum . If you really like full bass, don’t skimp on your subwoofer. Also, keep in mind that you can have two if you really want to rock the house. Why TWO subwoofers? While some use two subs to cover both stereo channels, the truth is, the human ear has very little ability to discern direction from low frequency signals. As sound waves increase in size (for lower frequencies) , the directional cues decrease. The real reasons for using more than one subwoofer are as follows: A. Increasing available bass output – In smaller rooms, one decent subwoofer should suffice at low to moderate volume levels. At louder levels or in larger rooms, the requirement for more bass volume increases proportionately. Two subs can provide this increase without distorting either sub. B. Increase dynamic range –some situations, liker bass-heavy Rap, or depth Charges or a heavy T-Rex stomp, require much greater instantaneous output than one sub can provide. C. Better low-midrange separation – While you won’t be able to hear left to right Panning of bass, you will be able to hear bass on both sides of the room. Spreading Out the bass provides a more natural listening experience. Why have a LFE output at all? Honestly, the “point one” in 5.1 mixes was originally intended to feed a speaker capable of producing low frequency effects in theaters. It was not developed to make music sound better, even though it can have that effect with Dolby Digital program material that properly utilize the LFE channel . The LFE channel was developed to simplify the wiring of a home theater. While it can be very effective in movies, it also can drain the life out of your favorite music. If you use the setting above, you should not need the LFE channel at all. When you turn the subwoofer setting to “no” or “off”, the signal that would have gone to the LFE is sent to your front left/right speakers. That signal will now be captured by your sub(s), allowing you to make the most your home theater speaker setup. Happy booming!
