Learn: Home » Bass Management 101: Great lows for stereo sound
The path to better bass
1. Does your receiver even send a signal to the subwoofer output when in stereo mode?
Most do, but some receivers' subwoofer outputs work exclusively with multichannel sources. So, in stereo mode, your subwoofer's functionality would be reduced to that of a silent footstool. The only thing worse than bad bass is no bass, and that's what you'd get. If you're unfortunate enough to own a receiver that falls into this category, skip down to question #4.
2. If your receiver's subwoofer output does send a signal in stereo mode, is it a full-frequency signal or a filtered, low-frequency signal?
As you know, your subwoofer is only designed to produce low-frequency sounds. Making your sub produce midrange or high frequencies is a recipe for disaster. So, how does your subwoofer know to only play the low frequencies? Well, it doesn't — it will try to play whatever signal reaches the driver. To prevent your sub from trying to play a searing Van Halen guitar solo or Tiny Tim's quavering vocals, a crossover filter blocks frequencies above a certain level (usually somewhere between 80Hz and 150Hz).
This crossover filter can live in your receiver or in the subwoofer unit. It's important to know if your receiver's sub output sends a full-frequency signal or a filtered low-frequency signal (check your receiver manual for details). Most are filtered, but if it happens to be a full-frequency signal, you'll have to count on your subwoofer's crossover filter to edit out the higher frequencies, which is just fine. But wait a minute, I know what you're thinking
3. What if both your subwoofer and your receiver have a crossover filter? Couldn't that cause some problems?
The answer is yes. And, the fact is, most people will probably end up with this dilemma because most powered subwoofers and most receivers have crossover filters. When you have two different filters wrestling over the same signal, you can end up with some very bad bass. You might be able to adjust the filters so they don't interfere with each other. This will require some experimentation.
But wouldn't it be great if you could just shut off one of the filters? You may be able to do just that — many subs come with either an LFE/normal switch or separate LFE and normal inputs. Just set your sub to LFE (or use the separate LFE input) and presto, the subwoofer filter is defeated, and your receiver's filter is flying solo. Everything's great, right? Well, kind of.
There's a very good chance that your subwoofer filter is better than your receiver filter and here's why: subwoofer filters are usually "continuously variable," meaning you can adjust the crossover point by single frequency units. You can get an ideal blend between your stereo speakers and sub. By shutting it off, you're losing one of the really cool features of your sub.
Receiver crossovers are often not variable; you're stuck with a crossover frequency preset by the manufacturer, and it might not work well with your sub and stereo speakers. And even if your receiver filter is variable, you usually can only choose between something like two and six different frequency settings certainly inferior to the fine-tuning you can do with a continuously variable subwoofer filter.
If you shut off your subwoofer filter and discover that your receiver filter is set just right for great bass performance with your system, you're good to go. If not (and if your receiver doesn't allow for adjustments that work for your gear), you're probably in trouble, because most receivers don't allow you to shut off their built-in crossover filter.
So, now what do you do?
 Most subwoofer back panels give you a lot of options — make the most of them! |
1. Does your receiver even send a signal to the subwoofer output when in stereo mode?
Most do, but some receivers' subwoofer outputs work exclusively with multichannel sources. So, in stereo mode, your subwoofer's functionality would be reduced to that of a silent footstool. The only thing worse than bad bass is no bass, and that's what you'd get. If you're unfortunate enough to own a receiver that falls into this category, skip down to question #4.
2. If your receiver's subwoofer output does send a signal in stereo mode, is it a full-frequency signal or a filtered, low-frequency signal?
As you know, your subwoofer is only designed to produce low-frequency sounds. Making your sub produce midrange or high frequencies is a recipe for disaster. So, how does your subwoofer know to only play the low frequencies? Well, it doesn't — it will try to play whatever signal reaches the driver. To prevent your sub from trying to play a searing Van Halen guitar solo or Tiny Tim's quavering vocals, a crossover filter blocks frequencies above a certain level (usually somewhere between 80Hz and 150Hz).
This crossover filter can live in your receiver or in the subwoofer unit. It's important to know if your receiver's sub output sends a full-frequency signal or a filtered low-frequency signal (check your receiver manual for details). Most are filtered, but if it happens to be a full-frequency signal, you'll have to count on your subwoofer's crossover filter to edit out the higher frequencies, which is just fine. But wait a minute, I know what you're thinking
3. What if both your subwoofer and your receiver have a crossover filter? Couldn't that cause some problems?
The answer is yes. And, the fact is, most people will probably end up with this dilemma because most powered subwoofers and most receivers have crossover filters. When you have two different filters wrestling over the same signal, you can end up with some very bad bass. You might be able to adjust the filters so they don't interfere with each other. This will require some experimentation.
But wouldn't it be great if you could just shut off one of the filters? You may be able to do just that — many subs come with either an LFE/normal switch or separate LFE and normal inputs. Just set your sub to LFE (or use the separate LFE input) and presto, the subwoofer filter is defeated, and your receiver's filter is flying solo. Everything's great, right? Well, kind of.
There's a very good chance that your subwoofer filter is better than your receiver filter and here's why: subwoofer filters are usually "continuously variable," meaning you can adjust the crossover point by single frequency units. You can get an ideal blend between your stereo speakers and sub. By shutting it off, you're losing one of the really cool features of your sub.
Receiver crossovers are often not variable; you're stuck with a crossover frequency preset by the manufacturer, and it might not work well with your sub and stereo speakers. And even if your receiver filter is variable, you usually can only choose between something like two and six different frequency settings certainly inferior to the fine-tuning you can do with a continuously variable subwoofer filter.
If you shut off your subwoofer filter and discover that your receiver filter is set just right for great bass performance with your system, you're good to go. If not (and if your receiver doesn't allow for adjustments that work for your gear), you're probably in trouble, because most receivers don't allow you to shut off their built-in crossover filter.
So, now what do you do?
