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What to do if your subwoofer only works sometimes (1 Viewer)

keithling

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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!
 

David Willow

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I disagree (mostly). Set your speakers to "small" (even if they "look" large) and allow the crossover in the receiver to redirect the bass. This is especially important if you use the Auto EQ (like Audyssey) in modern receivers. For example, MultiEQ XT has 8x the filters for the subwoofer (compared to the sattilites).

Also, the reason to use 2 subs is simple. It helps deal with room modes. You can get closer to a flat repsonse across multiple seats with more than one sub. In very large room, you can get a slight (3db) increase in loudness.
 

Jason Charlton

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A couple of observations:

1) First of all, it's a flawed assumption to think that you're SUPPOSED to get large amounts of bass, simply because a DVD or CD has "5.1" stamped on the front. Watch "Jurassic Park", then watch "Bowling for Columbine" and tell me if you think one of them has a screwed up sound mix. Everything is mixed according to the wishes and desires of the sound recorders/engineers and filmmakers. It's really not up to the audience to decide how the end result should sound.

2) Secondly, as David pointed out, modern A/V receivers have much more sophisticated and capable bass-management and equalization circuitry than any off-the-shelf subwoofer. In addition, this bass-management is applied to the entire audio stream, rather than just the L/R front channels in the setup you describe.

3) Let's not forget that depending on your listening mode/DSP setting for each input, the bass management may be handled differently for each source. There's no substitute for a properly configured and calibrated system.

4) Finally, your claim that speaker-level inputs are the "Best" connection type is puzzling to me because, in my experience, once you get above a certain price/performance threshold on subwoofers, the speaker-level inputs all but disappear, leaving only the line-level input.

Edit: I stand corrected on this last point - high-level inputs are quite commonly found on many higher-end subwoofers. I simply haven't heard of too many people actually using them.
 

Ed Moxley

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Also, when using digital connections, the receiver is doing the processing, so you can have bass management. When using 5.1/7.1 multi-channel analog connections, the player is doing the processing (as with sacd and dvd-a), and most don't allow any bass management at all. The very few that do offer bass management, are very limited, by my understanding.

I set all my speakers to small, and let the subwoofer handle all the bass. Afterall, that's what's it's made to do. I haven't tried to see if I have sub with stereo, because I don't listen to stereo. I use DPL IIx when playing music, because I like surround sound. Stereo just sounds like it's missing something................
 

ShanonS

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I'll second what Dave said. There are very few instances where this setup would work better. The first would be with fairly old equipment. There are older receivers that are not great at handling the bass and this setup might be better. Other than a few isolated cases, this would not be the best setup. Most receivers that are not fairly old will handle the bass x-over between all of your speakers much better than the basic crossover in most subs. Higher end receivers will allow you to set different crossover/cutoffs for different speakers and route this correctly to the LFE channel and will correctly handle the rolloff of those speakers to give a smooth transition between it and the LFE. Many of the newer receivers will handle most of this automatically based on actual measured response of your speakers. My current receiver handles bass on all material through all connections very well, including all music inputs. The proper setup is to set all of your speakers to small, in most cases including your large floor standing main speakers. If you have the option, you can give those speakers a lower cut-off point, but unless you have truly full-range speakers with their own powered sub or dedicated amps that can truly drive them full range, they should never be set to large if you have a separate sub.
 

keithling

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For those who set up a home theater only for movies, and NOT for music/music videos/concerts, using the LFE would probably be best. I suppose I must mention that my home theater system is also my primary music listening system. I like to listen to a lot of stereo CDs. I'm not listening in special modes, just plain stereo. LFE works well with movies, but my Pioneer receiver doesn't "manage" bass unless it's specifically LFE. When I had the sub hooked to the LFE, all the bass was going to the front L/R speakers. There was absolutely no sound going to the sub.

When you set the receiver subwoofer setting to "no" or "off", the bass management automtically sends it to the front left and right speakers. If you set up your sub levels properly, you will rarely ever have to adjust them.
 

keithling

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Originally Posted by Jason Charlton

A couple of observations:

1) First of all, it's a flawed assumption to think that you're SUPPOSED to get large amounts of bass, simply because a DVD or CD has "5.1" stamped on the front.

Agreed. I am referring to when I use my system for music. When playing stereo CDs, the sub was not receiving ANY signal whatsoever. That has more to do with the fact that the source goes into analog processing and not digital processing.
 

David Willow

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Originally Posted by keithling

For those who set up a home theater only for movies, and NOT for music/music videos/concerts, using the LFE would probably be best. I suppose I must mention that my home theater system is also my primary music listening system. I like to listen to a lot of stereo CDs. I'm not listening in special modes, just plain stereo. LFE works well with movies, but my Pioneer receiver doesn't "manage" bass unless it's specifically LFE. When I had the sub hooked to the LFE, all the bass was going to the front L/R speakers. There was absolutely no sound going to the sub.

When you set the receiver subwoofer setting to "no" or "off", the bass management automtically sends it to the front left and right speakers. If you set up your sub levels properly, you will rarely ever have to adjust them.
It works the same way for both unless your receiver is older (in which case it shouldn't work for either). Stereo mode for my 18 month old Onkyo redirects everything to the sub below the crossover I set. Again, if you do not have your system setup PROPERLY (speakers set to small, not large), then you will not get bass redirected to the sub.

BTW - Do you realize that "large" has very little to do with the speaker size? It really means "bass managed" (small) or "not bass managed" (large).
 

Jeff Gatie

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I always said that when making up the Large and Small settings in a receiver's setup, the manufacturers should never have chosen the same adjectives as those used to describe male body parts. Nobody wants to own any that is "small," no matter what it is. They might just as well named the settings "miniscule" and "porn star" and got it over with.

People, the fact that you can set your speakers to small means you have a very large, pulsating, throbbing sub. Run with that thought.
 

keithling

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Originally Posted by Jeff Gatie /forum/thread/293095/what-to-do-if-your-subwoofer-only-works-sometimes#post_3607905
LOL

I used to have a pair of Polk SDA- 2 speakers. Those ARE big speakers, but my manual didn't tell me that my sub would get no signal if I set the front speakers to large.

BTW, I got a second Polk PSW505 today for my birthday! :D
 

keithling

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BTW, my home theater sound system is as follows:
Pioneer VSX-515 (about 5 years old)
Polk Monitor 70 (front left & right)
Polk CS2 (center channel)
Polk Monitor 30s on stands (rear left & right)
2 Polk PSW-505 subs

I'm glad to hear there are some receivers now that send all lows to the LFE. They should've never used the phrases "large" or "small" in a manual that will be read mostly by men.
 

Scott Merryfield

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Originally Posted by David Willow





It works the same way for both unless your receiver is older (in which case it shouldn't work for either). Stereo mode for my 18 month old Onkyo redirects everything to the sub below the crossover I set. Again, if you do not have your system setup PROPERLY (speakers set to small, not large), then you will not get bass redirected to the sub.

BTW - Do you realize that "large" has very little to do with the speaker size? It really means "bass managed" (small) or "not bass managed" (large).
Bass redirection works in all modes on my current and previous Pioneer receivers, too, when the speakers are set to SMALL. As has been mentioned by numerous people already in this thread, your problem was not in using the single RCA connection for your subwoofer, but instead in how you had configured your receiver.

If you have a newer Pioneer receiver with the MCAAC auto-calibration feature, you will find that the program will sometimes automatically set some or all of your speakers to LARGE. The first thing you need to do after running the auto calibration program is manually change this setting to SMALL for all your speakers, and adjust the crossover setting appropriately for your particular speakers -- I have mine set at 80Hz.

Both my old Elite 47TX and current Elite 94TXH set some of my speakers to LARGE, requiring the above changes. That is the only thing I disliked about Pioneer's MCAAC program.
 

keithling

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Originally Posted by Scott Merryfield




Bass redirection works in all modes on my current and previous Pioneer receivers, too, when the speakers are set to SMALL. As has been mentioned by numerous people already in this thread, your problem was not in using the single RCA connection for your subwoofer, but instead in how you had configured your receiver.

If you have a newer Pioneer receiver with the MCAAC auto-calibration feature, you will find that the program will sometimes automatically set some or all of your speakers to LARGE. The first thing you need to do after running the auto calibration program is manually change this setting to SMALL for all your speakers, and adjust the crossover setting appropriately for your particular speakers -- I have mine set at 80Hz.

Both my old Elite 47TX and current Elite 94TXH set some of my speakers to LARGE, requiring the above changes. That is the only thing I disliked about Pioneer's MCAAC program.
Of course, the Pioneer manual never said that if you have a subwoofer, you should set all of your speakers to small. It never said that if you select large for the front speakers, the subs will not get a signal at all. Yet, that was the case. The speaker wire set up works very well, and is consistent. Also, I don't have to use a splitter to run two subs.
 

David Willow

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Originally Posted by keithling


I'm glad to hear there are some receivers now that send all lows to the LFE. They should've never used the phrases "large" or "small" in a manual that will be read mostly by men.
As does yours. You are free to set it up as you like, but for anyone reading this thread, there is a better way. If done correctly, the bass will be as good as it can be with the subs you have.

BTW - It is even MORE important to setup dual subs correctly. Having 2 subs can make a big difference in many rooms, but the learning curve to get them right is high. I suggest you do some serious reading.

Here's a couple sites with good general sub information to get started (in addition to reading lots of stuff here, of course).

http://www.robbroy.net/HT/SubwooferErrors.cfm

http://www.audiopulse.com/know-how/subwoofer-driver-guide/myths-about-subwoofers/
 

Ed Moxley

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Here is an excellent thread about how to hookup stereo subs:
http://forums.soundandvisionmag.com/showthread.php?t=75628
Some good info.............
 

Scott Merryfield

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Originally Posted by keithling



Of course, the Pioneer manual never said that if you have a subwoofer, you should set all of your speakers to small. It never said that if you select large for the front speakers, the subs will not get a signal at all. Yet, that was the case. The speaker wire set up works very well, and is consistent. Also, I don't have to use a splitter to run two subs.
The terms LARGE and SMALL are used by virtually all receivers. not just Pioneer. It may not have been clear to you, but they are standard terms used to describe bass management. As David said, you are free to set your receiver up however you wish, but the best way is still to use the subwoofer out from the receiver to the sub's line level input and setting up your speakers properly in the receiver's setup menus (which usually means setting all speakers to SMALL).
 

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