3 Way Crossover Design Example

1. Stereo Crossover
2. Stereo Crossover Definition
3. Passive Crossover Car Audio
4. Stereo Crossover Rackmount
5. Stereo Crossover With Subwoofer Output

• A crossover is essential to split the audio signal into separate frequency bands and feed the correct driver. Full-range car speaker usually have built-in crossovers to filter out frequencies but if you’re into further customizing your sound system, installing a separate outboard crossover is a smart choice that will give you total control.
• Speaker Crossovers, Parts, L-Pads, Repair Accessories - We stock high quality 2 Way Crossovers, 3 Way Crossovers, L-Pads, and Protection Fuse Bulbs fo.

Note, this sample crossover makes use of many of the calculators found onthe menu on the left. You should also review the Crossover Guidefor help with this example.

For the mid/woofer crossover there are 4 octaves between 200-3.2k Hz, 200-400-800-1600-3200. 800 Hz is the middle frequency, with 2 octaves flat in either direction. For the tweeter/mid crossover, there are only 1 octaves, 2000-4000. 3k Hz is the crossover point with 1/2 octave stable in either direction. Clarion MCD360 – Best Overall Audio Crossover. The first unit on this roundup is a first-rate product.

For this example, I picked 3 ScanSpeak drivers for a 3-way speaker(the same 3 used on the Speaker Box Example.Note: This example old and the characteristics of these drivers have since changed.These drivers were not picked because of how well they worked together, but ratherbecause they have problems that can be solved with the proper circuit.The drivers I chose were:

All of the drivers are 8 ohms. There are no differences in output caused bydifferent impedances with the drivers. The tweeter has 2db sensitivity over the mid,and the woofer has 1db sensitivity over the mid. Resistors will be used to balanceout the sensitivity/load problems. An L-Pad / Driver Attenuation Circuit will be usedto lower the tweeter output by 1db and the woofer output by 2db.

The Fs (free air resonance) of the tweeter is at 1000Hz. This is thefrequency at which the tweeter will resonate, and produce a large positive spikein the frequency response. A series-notch filter will be used to remove this spike.

You want to pick crossover points between the two drivers.Remember that it is a base 2 logarithmic scale. For the mid/woofer crossover there are4 octaves between 200-3.2k Hz, 200-400-800-1600-3200. 800 Hz is the middle frequency,with 2 octaves flat in either direction. For the tweeter/mid crossover, there areonly 1 octaves, 2000-4000. 3k Hz is the crossover point with 1/2 octave stable ineither direction. These two drivers have little overlap, and normally would not beused together.

In the mid/woofer combo, the frequency range / response is stable2 octaves beyond the crossover point, and for the tweeter/mid, only 1/2 octave.Therefore, a higher order crossover must be used with the tweeter/mid than with themid/woofer. A 2nd order, maybe even a 1st order crossover can be used with themid/woofer combo, while a minimum 3rd order crossover should be used with the mid/tweeter.

Some people believe that it is best to use a low order crossovers when possible,preferably only 1st order. This does have some benefits. With the greater frequencyoverlap, voices will not seem to jump from one driver to another as quickly as theywould with a steep crossover. It also follows the minimalist approach where the simplerthe circuit, the less distortion and modification of the signal is introduced.The problem with 1st order crossovers is that the frequency overlap in the driverswould have to always be at least 2 octaves (or more) in each direction from thecrossover point. It would probably require at least 4 drivers.

Another belief is that even order (2, 4, 6...) order crossovers should beavoided. Even order crossovers tend to have spikes or dips in the frequency responsearound the crossover point. These spikes can be as bad as -30db, but can easily besolved by reversing the polarity of only one of the speakers, limiting the spike toabout +- 3db.

For this example, a 3rd order crossovers at 3000Hz and a 1st order crossover at800Hz will be used.The Crossover Calculator was usedto determine the crossover components. These are the results of the 2 crossovercalculations:

Now, these two diagrams must be combined into a 3-way diagram. When working with3 or more speakers, at least one speaker must be bandpass. Bandpass means that thespeaker has a high pass filter (HPF) that filters out low frequencies and letshigh frequencies pass through, and a low pass filter (LPF) that filters out highfrequencies and lets low frequencies pass through. In this system, only the midwill be bandpass. When wiring multiple speakers, you usually start with the largestspeaker. All speakers above that one are run through the HPF. In our 3-waysystem, both the mid and tweeter are run though the HPF from the woofer/mid crossover.

This diagram has been simplified, and only the positive (+) lead is shown, butyou get the idea. The reason for going woofer to tweeter is so that the HPF is beforethe LPF for each bandpass speaker. The inductors (coils) in a LPF have resistance.This resistance affects the impedance of the entire circuit.If you put the LPF before the HPF, the amp will not have a stable load to work with.

Although the diagrams in this document show each of the high speakers being run throughmultiple high pass filters, this is not necessary. In the above diagram, the inputfor the second and third crossover could be directly tied to the main input insteadof the high output from another crossover.

Stereo Crossover

The next step in designing the crossover circuit is to design the l-pads toequalize the different driver sensitivities. 2db needs to be removed from the tweeter,and 1db from the woofer. The L-Pad / Driver Attenuation Calculatorwas used to determine the L-Pad components.

The last design step is the series notch filter. The Fs is at 1000Hz, and thecrossover point is at 3000Hz with a 3rd order crossover. The resonance spike is over oneoctave from the crossover point, and may be damped enough that it will not be noticed,but it will be added to the circuit anyway. TheSeries Notch Filter Calculatorwas used to determine the necessary components.

Now, the crossovers, l-pads, and series notch filter must be combined into onecircuit. There is no standard as to which parts come first, but the common method iscrossover then l-pad then series notch filter.

This is the complete circuit for the 3-way system. Note: A bi-amp/bi-wiredsystem would look something likethis.

With the crossover designed the next step is to procure the parts: the capacitors,resistors, and inductors. See the Crossover Guide for explanationson the different types of these components (Mylar vs. polypropylene capacitors...). In the end,it is about how much money you want to spend, which should be no more than half the cost of thedrivers.

When you buy inductors, capacitors, and resistors there are usually only certain valuesavailable. These values are referred to the E ranges are discussed inResistor Colors.That is why the values in the crossover tables for1st,2nd,3rd order Butterworth crossovers haveslightly different values than what the Crossover Calculator produces. The tables usecommonly available inductors and capacitors. A 16.58uF Capacitor (as required for the first crossover)is not something you can find in a store but you should be able to find something close.You can also use multiple differentcapacitors, inductors, and resistors in series or parallelto achieve the desired value.

With the crossover designed and parts in hand, the next step is to build the crossover.For this step, you will need a piece of wood to mount the parts to, a hot glue gun and some glue sticks,a soldering iron and solder, and finally some wire. Any piece of wood will work as a mounting board.You can even use the MDF for the speaker itself. First, layout the components on the board accordingto the crossover diagram that you have made. Try to place the components close enough to each otherso that jumper wires are not required to connect the different components together.Cut the board to size once you have decided on the layout.

Once the components are in place, use your hot glue gun to mount them to the board. Be sure that theinductor coils are not near each other and that each one is on a different axis to eliminate'inductive coupling' (See the Crossover Guide for more info).

Now solder the different components together. If possible, solder the components directly to each other.Otherwise, use short jumper wires to connect them. I prefer using 12AWG for the crossover but it is not required.

Finally, mount the crossover in your speaker, connect the crossover leads to the back of your binding post,and connect the speakers to the crossover. Positive (+) to Red. Negative (-) to Black.When testing your speaker, pay attention to possible Phase Shift problems(See the Crossover Guide)where the sound volume dips significantly at one of the crossover points. If you suspect you have a Phase Shiftproblem, reverse the leads (+/-) on one of the speakers to see if the system gets louder. If so, then youhave found and solved your problem.

The final step in any design is experimentation. Remember that every component(capacitors, inductors, and resistors) each exhibit all 3 properties (capacitance, inductance, and resistance).This is why thicker copper wire is desired for inductors - to lower its resistance.No design is perfect, and improvements can be made by making small changes to the crossover.This may not be possible if you don't have an electronics shop filled with parts.Ordering foil inductors one at a time can get expensive. The best alternative may be towind your own inductor coils using the Inductor Calculator.Start large and then unwind (but don't cut) the inductor to experiment with different values.

Bass management is a necessary process when configuring your home theater because it affects your entire sound system. Getting the perfect blend of audio depends on your subwoofer’s crossover setting. If you fail to get it right, every speaker in your sound system won’t work in harmony, and we don’t want that to happen, right?

When setting the subwoofer crossover, you want the right amount of overlap with the speakers. Subwoofers can take your system to a whole new level, but you never want to know that it’s there. Too much overlap creates a peak, too little creates discontinuity, but the right amount creates harmony.

Finding the right blend when setting a subwoofer crossover can be tricky because, in a lot of cases, you have to do it by ear. However, there are a couple of things about bass management that can help you configure your sound system. Stick around as we cover each of them in great detail to help you achieve the best possible audio experience.

The Importance of Subwoofers for Your Sound System

Regardless of your current setup, you need a subwoofer. It can bring new life to your sound systems that you can never achieve, even with the best speakers.

You can find speakers that take pride in their sophisticated bass management. However, there’s no speaker right now—even the ones that have a built-in subwoofer—that has the range close to what a dedicated sub can produce. If you want to take your movie-watching and music-listening experience to a whole new level, you need a subwoofer!

Some might argue that their speakers can produce deep bass and heart-pounding effects they want for their media room.

So, they don’t want to deal with another hassle of configuring a subwoofer. That’s true to some extent, but if you want to experience the depth of true high definition audio, then a subwoofer with the right crossover setting is a must!

Also read: Which Way Should A Subwoofer Face In Home Theater?

What Is a Subwoofer Crossover?

Before we proceed, let’s clear some terms that we’ll use in this post, which may not be familiar to you. Here are some essentials that you need to know about subwoofer crossover settings:

• LFE or Low-Frequency Effect is the part of your sound system that produces deep sounds when listening to music or heart-pounding effects when watching movies. It’s the “.1” in a 3.1, 5.1 or 7.1 surround sound setup.
• LFE + Main is a crossover mode that we find in sound systems where it sends deep sounds lower than the crossover point to both the subwoofer and speakers. It’s configurable, and you can try setting it up for your sound system, but it’s often unstable, and it would be best to leave this setting to default.

• Low-Pass Crossover is the frequency where your subwoofers will start working to reach deep notes that aren’t possible for the speakers that we have today. Typically, a low-pass crossover is anywhere from 40Hz and could go up to 60Hz to 100Hz.
• High-Pass Crossover is the frequency above the low-pass crossover where your speakers will start working and take over from a subwoofer. If you’re using a subwoofer that features a high-pass crossover, it’ll be fixed and will remain the same regardless of your set up.
• Large speakers are capable of producing full-range audio. If you have this type of speaker in your setup, you’ll be able to produce sounds as low as 20Hz. You need a dedicated sub because there’s no speaker now that is capable of reaching it.
• Small speakers are the ones that create the mix for crossover. It can produce sounds at frequencies lower than your main speakers but higher than your subwoofer. It’s mostly responsible for the transition that happens when your system gets into the crossover.

So now, what’s a subwoofer crossover?

Well, it’s the frequency where your subwoofer and speakers work together to cross a higher or lower range. When listening to music, and your system sends out a signal to produce deep sounds, your main speakers will gradually roll off to give way to your subwoofer.

When you need higher notes, your sub will slowly roll off to give way to your main speakers. This seamless transition is responsible for producing audio that acts as if it’s coming from one entity.

This process may sound too simple, but in reality, a subwoofer crossover is a vital configuration that you have to make to ensure that every speaker in your system works in harmony. That’s why it’s crucial to understand how a properly configured sound system should sound before you start setting your subwoofer crossover.

Configuring the Sound System: How Should It Sound?

When you connect your sub to an amp speaker post, you can set the subwoofer crossover below, close, or above your speaker ratings.

Many people get overwhelmed with this process because when you look at the back of large speakers, you’ll see several control knobs that you can use to configure the crossover. Unfortunately, there’s no exact formula to set your subwoofer, and you’ll have to do most of it by ear.

As a general rule, you want your large, small, and main speakers to overlap. However, you can’t just go at the back of your sub to configure because it needs to have the right amount of overlap. Your audio will create a peak in transition if you set it with too much overlap; too little creates depth or discontinuity in harmony. You don’t want both of these effects when configuring your sub to work with your sound system.

Part of the reason is that you want your subwoofer to be a part of a well-synchronized system that creates harmony. If you’re using a subwoofer, and someone tells you that you have a beautiful, distinctive subwoofer, your setup fails. A properly configured sub won’t stand out from the rest of your sound system, and it shouldn’t produce audio that makes it sound like it’s coming from a separate entity.

Deep bass sounds good, especially if you’re using a full-range subwoofer. But without the right amount of overlap, you’ll either hear a sudden drop in notes that sound like an amplifier just went awry, or a very short—but noticeable—cut in your audio. A proper crossover setting creates a smooth transition from the low-pass to high-pass crossover without any noticeable interference.

How to Set Up Your Subwoofer Crossover

Most of the systems that we use today include an equalization feature that handles the output for audio. As technology improves, so does this feature. Nowadays, the speakers that we use for our sound system can scan our set up and then automatically set the right crossover, using the specifications of the speakers that are in our system.

However, this equalization feature is still far from being perfect. You still have to make some manual adjustments to achieve the right amount of overlap that you want your sound system to have.

Look at the back of your subwoofer, then set the low-pass crossover at least 10Hz higher than your main speakers’ range. This range is the starting point when configuring your crossover. If your center speaker can produce 80Hz to 120Hz, then you want your low-pass crossover to be anywhere close to 90Hz.

This configuration means that both your center speaker and subwoofer will produce output once audio reaches 90Hz. Your center speaker will roll off when it gets lower than 80Hz, and your subwoofer will roll off when it gets higher than 90Hz. With this setup, you’re telling your system to start the crossover at 90Hz and end at 80Hz.

Finding the range of your main speakers is easy, but in case you’re not sure about it, you can use a subwoofer matching tool to configure your crossover accurately. This process may sound simple, but creating a 10Hz overlap is just a starting point when setting your sound system.

Since different speakers have different ranges, you may have to do several trial and errors to find that sweet spot—a smooth, seamless transition that works in harmony.

How to Test the Subwoofer Crossover

After setting up the starting point for the crossover, you’ll want to test your system to see if it works smoothly. Testing your subwoofer crossover can be tedious, and it’ll be even harder if you’re working on it using an unfamiliar sound. So, you must use a familiar sound that you’ll recognize with a clear picture in your mind.

If you’re noticing even the slightest peaks in frequencies, you should start reducing your overlap until it becomes smooth and unnoticeable. If there’s a noticeable discontinuity, slowly increase it to get the transition you want.

There’s a chance that during your tests, you’ll hear bass bumps while your speakers and sub are overlapping. It’s not an issue with your crossover, but rather with the output volume.

You can fix these bumps by adjusting your subwoofer volume to match your main speaker output volume. Both output volume should match because it’ll affect the smooth transition that you’re trying to create.

Remember, when setting the crossover manually, you will, almost, always have to do it by your ear. However, there’s always an exception, or in this case, a tool that you can use to check your subwoofer’s crossover.

You can use a bass frequency sweep whenever you don’t feel like getting down to the specifics of configuring sound systems, or you’re not comfortable in making the adjustments on your own.

A bass frequency sweep is a tool that uses a tone that starts at the highest frequency, then ends at the lowest possible for any setup. The best thing about this tool is that you, most likely, already have this in your possession. You’ll find tones like this embedded in any THX-certified movie!

Any movie that you have in your arsenal with a THX logo has a THX Optimizer app that you’ll find in the Extras section on the menu. This app will produce the tone that is similar to a bass frequency sweep, which will help you determine whether you’re experiencing drops, peaks, or bumps in your sound system.

When you run this app and hear a distinct sound that shouldn’t be in your system’s audio output, reconfigure it accordingly. Reduce the overlap when you have a peak, increase it if you have a drop, or adjust the volume output when you have a bump.

However, there are times when, despite several adjustments, you’re still getting inconsistencies with your output. When it happens, then maybe, the position of your subwoofer is a bit off for your sound system.

How to Position Your Subwoofer Properly

You may have heard this advice before: place your subwoofer in the corner or close to the wall to get more bass. That’s true, but it may not be the kind of bass that you expect. It could be one of the reasons you’re getting peaks or drops with your sound system, despite configuring it according to the results you’re getting.

Stereo Crossover Definition

Unfortunately, carte blanche doesn’t work when looking for a spot that you can use for your subwoofer. What you can do is to use a simple test on where you should put your subwoofer:

1. Put your subwoofers at the center of your room
2. Play a sound that uses deep bass, anything that is familiar to you.
3. Move around the room to see where you’re getting the best sounding LFE, and remember these spots.
4. Keep moving around until you have 3 to 4 spots where the bass sounds best.
5. Place your subwoofer on each of these locations, then do a bass frequency sweep.
6. Leave it where you’re getting the best result, then configure the crossover, both low-pass and high-pass, according to the test results.

This method may be unpredictable, and you might end up having your subwoofer in the least ideal locations. However, if you want to get the right amount of overlap, you’ll have to redesign, sometimes even reconstruct, your media room.

If you don’t like the idea of reconfiguring your media room, then you may want to try the Rule of Thirds when placing a subwoofer. This rule means that if you measure your room’s size from the door to the adjacent wall, then use a third of its size as the space between your wall and subwoofer; you’ll get better bass output.

Passive Crossover Car Audio

The Rule of Thirds doesn’t always produce the best bass, but it reduces the occurrence of standing waves and nulls. It also saves you from the trouble that you may have to go through when redesigning or rebuilding your media room.

You can also try the corner to see if it can help you produce better test results. No, we’re not contradicting ourselves here, it’s just that sometimes, the corner is the best location for a subwoofer.

However, you can’t just stick it in there and hope to get the best bass output. You may have to place anywhere from 6 to 8 inches out from the corner, then slightly move it after each test to find the sweet spot for your subwoofer.

Stereo Crossover Rackmount

Also read:Pros and Cons of 2 or More Subwoofers in Home Theaters

Two Common Mistakes When Positioning a Subwoofer

When trying to position your subwoofer, you can try every spot in your media room aside from these two: inside another cabinet and in-wall. First is a no-brainer, but the second is getting more and more popular these days. Let us explain why.

Sometimes, there’s just not enough space in your room to house a gigantic subwoofer, other than the cabinet, right?

Unfortunately, anywhere in your room is a better place for a subwoofer than leaving it crammed inside a cabinet. That’s because subwoofers are non-directional low-frequency speakers that need some breathing room. So keeping it inside a cabinet will create a hard cap with the output that they can produce.

Installing a subwoofer inside the wall is becoming popular because it’s sleek and reduces the clutter in your room. Although there are high-quality in-wall subwoofers you can buy, you’ll need a special box to keep it performing well without distortion.

Remember, subwoofers need enough breathing room to produce high-quality audio, and placing it inside the wall limits its output.

Let’s say you’ve been to a friend’s house and found out that he’s using an in-wall subwoofer. It sounds nice, perhaps, better than yours. There are only two possible reasons for it: either he specializes in installing and configuring sound systems or went through a lot of effort to set it up and spent way more for it to work!

Final Thoughts on Subwoofer Crossover Settings

Every sound system needs a full-range subwoofer. It has the power to take your music-listening experience to the next level, but you have to configure it correctly. The subwoofer crossover is a crucial part of setting your speakers to work harmoniously and avoid inconsistencies with the output.

Three things can affect the output of your sound system when testing your subwoofer crossover:

• Overlap of your large, small, and main speakers
• The volume output of your subwoofer and speakers
• Position of your subwoofer within the media room.

You must consider all of these when setting your subwoofer crossover because it can make a huge difference with the output that you produce.

Check out my recommended subwoofers.

Stereo Crossover With Subwoofer Output

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