Speaker Crossover Calculator + Crossover Building Tips

Ready to design and build your own speaker crossover? You’re in the right place!

Here’s a very easy-to-use speaker crossover calculator along with great info to help you.

Note: Javascript must be enabled in your browser to see or use the tool.


speaker crossover calculator section image

You can use my speaker crossover calculator to generate parts values to build your own capacitor, experiment with different values, and more.

How to use the calculator

  1. Select the crossover type:
    • 4 types are available: 2-way 2nd order Linkwitz-Riley (12dB/octave), high or low-pass 1st order Butterworth (6dB/octave), 1st order 2-way Butterworth (6dB/oct.), and 1st & 2nd order 3-way crossovers.
    • A speaker crossover schematic matching the type you chose will be shown.
  2. Enter the speaker impedance (Ohms) as needed. This can be whole numbers, fractions, or both. (Ex.: 4 ohms, 3.6 ohms, etc.)
  3. Enter the crossover frequency desired. For 3-way crossovers, enter the bandpass upper (tweeter/midrange) and lower (midrange/woofer) cutoff frequencies. (*See my notes below regarding 3-way crossovers below.)

The calculator will output capacitor and inductor part values as needed. Parts are labeled to match the the example schematic shown for each type you select.

Reversing out of phase speakers for even-order designs

diagram of reversing out of phase speaker on speaker crossover

When building your own speaker crossover and using a 2nd order or other even-order designs, it’s important to remember to reverse one speaker driver to correct the 180 degree out of phase condition.

Crossover capacitors and inductors each add a 90° phase difference, giving even-order (2nd order, 4th order) crossovers a resulting 180° out of phase condition that will affect the sound.

It can result in destructive interference (sound wave cancellation) that occurs in the overlapping range of sound between the two speakers (three speakers in the case of a 3 way system) near the crossover frequency. It will also sound “weird” because the timing of the audio waves you hear conflicts with each other.

180 degrees out of phase speaker signal graph

Image showing 180 degree out of phase audio waves and the resulting in-phase (0° difference) condition after reversing the speaker.

Fortunately, there’s an easy fix: 

  • For 2-way crossovers, reverse the tweeter connection polarity.
  • For 3-way crossovers, reverse the bandpass speaker (midrange speaker) polarity.

You can do this by reversing the wiring at the speaker terminals in the crossover building stage or reversing the connection polarity label once it’s completed.

This is almost never a problem for ready-made crossovers you buy as this is usually already taken into account when they’re designed.

Why use a Linkwitz-Riley crossover for 2-way crossovers?

Linkwitz-Riley designs are hands-down one of the most commonly used for a number of reasons, one of which is their flat response where the woofer and tweeter crossover points overlap. While it’s true that plenty of other designs exist (Butterworth, Chebychev, Bessel, and others) they do not offer the same frequency response.

They certainly have useful applications but the Linkwitz-Riley (L-R) crossover is generally a great choice for standard speaker systems with a -12dB per octave slope.

The second-order L-R crossover is an all-pass configuration which sums to a flat magnitude…

The flat magnitude response, low sensitivity to offset, and in-band driver resonances have made the L-R a popular choice among manufacturers.Vance Dickason, The Loudspeaker Design Cookbook (7th ed.)

It’s also not sensitive to speaker driver resonance like some others. If you’re interested in the technical aspects of the different crossover designs available, I’d encourage you to read more.

I highly recommend Vance Dickason’s The Loudspeaker Design Cookbook for more detailed information as it shows examples and covers the topic in good detail. You’ll also learn tons of other speaker design info!

3-way crossover details for the calculator

To get the best results (3-way crossovers are NOT simply an extension of 2-way designs), the calculator uses a 3-way all pass crossover (APC) design with a sufficient frequency range between the high pass frequency and the low pass frequency.

You can also use a general rule based on the ratio of the high pass cutoff (Fh) and low pass cutoff (Fl):

Good 3-way crossover ratio: Fh/Fl = 8 or above.

Some great example 3 way frequencies to use are:

  • 3kHz/375Hz
  • 5kHz/625Hz
  • 6kHz/750Hz

Or, simply pick the upper frequency and divide by 8 to get the 2nd. Likewise, you can pick a lower frequency and multiply by 8 to get a good upper frequency.

However, do be aware that 3-way designs have a midrange output with a higher or lower dB level – in this case, the 3-way design provided has a 2.45 dB gain vs the tweeter and woofer. (This is a pretty minor difference however)

Generally speaking, the further apart the two crosspoints are, the better the combined response of the drivers will be (three octaves is a good starting point).

Crosspoints closer together than the three-octave ideal will suffer from complicated undesirable interference patterns.Vance Dickason

How precise do crossover capacitor and inductor part values need to be?

examples of speaker crossover capacitor and inductorI recommend trying to get fairly close to the calculated parts values; exact values are not practical or needed. For example, if the calculator recommends a 10.56mH (milliHenry) inductor, you’d try to get close to 10.5 mH, not 10.56mH. If you found a 10.2mH for example, that would usually be close enough.

Similarly, for the parts themselves, standard tolerance parts are fine for most designs. You don’t need to spend additional money on better tolerance components.

Of course, that doesn’t mean you shouldn’t use better quality or higher performance parts if you’d like – just that for most cases standard (20% – 15% tolerance) is fine.

Typical inductor and capacitor tolerances

The truth is that picking super-precise part values is kind of useless anyway because the components have as much as a 20% tolerance. For example, a 4.7 µF (4.7 microFarad) non-polarized capacitor, 20% tolerance, could have an actual capacitance as low or high as:

  • Low end: 3.76 µf
  • High end: 5.64 µF

As you can see, trying to pick the perfect parts values doesn’t make sense because they won’t be exactly that value anyway. That’s out of your control. Just try to get it pretty close if possible.

Most inductors are similar as well – especially air core wire wound inductors.

Affordable ways to get better sound performance

examples of film capacitors

Electrolytic capacitors are extremely common in speaker crossovers and filters..but did you know? There’s another little-known way to get better sound and better parts quality without spending a lot: polypropylene, polyester, and film capacitors.

They offer some nice benefits for only a little bit more money:

  • Longer life/don’t leak over time like electrolytic capacitors
  • Higher voltage handling (great for vacuum tube designs!)
  • Better audio performance (better for carrying the audio signal)
  • Vertical solder leads may make them easier to use in printed circuit boards or DIY projects
  • Some film capacitors are more compact than their counterparts

Film capacitors are generally bipolar (non-polarized) so they’re great for audio designs, but it’s important to always check the specs to be sure.

Also, be sure to verify their voltage rating – you’ll want a rating that’s at least equal to or higher than your amp or stereo’s output voltage generally.

Inductor options

solid core inductor example

They’re not mandatory, but you can also consider using iron core or metal-core inductors. These types have a more dense magnetic field characteristic, meaning they can be a bit smaller than air core models in some cases.

What voltage audio capacitors do I need?

how to calculate audio amplifier output voltage diagram

There’s an easy way to find the voltage you’ll need for audio capacitors in crossovers: you can find the approximate stereo amplifier or radio output voltage if you know the power per channel (RMS or continuous) and speaker Ohms.

Simply use this formula: V = square root(Ohms x Power)

This will give you the approximate voltage at maximum output power. Once you know that, I recommend using capacitors with a voltage rating at least the same if not higher voltage rating.

Otherwise, for standard power levels (not using maximum power out), you can use those up to the next closest value you can find.

Capacitors tend to be rated with standard values such as 16V, 25V, 48V, 50V, and so forth. Using a lower voltage rating part than needed can lead to the capacitor becoming damaged or exploding, leaking electrolyte which can corrode parts and materials.

Off-the-shelf bipolar capacitors sold for audio applications are normally of a sufficient working voltage, but it pays to always check Lower voltage bipolar parts (5V, 16V, etc.) are usually used for low-voltage (line level) electronics.

TIP: adjusting the crossover frequency to match parts on hand

Here’s a helpful tip I’ve picked up after building my own crossovers. If you’ve got parts on hand you’d like to use you might be able to do so by slightly changing the crossover frequency.

For example, let’s say you use the calculator for a 2-way 2nd order design at 3,000Hz, 4Ω:

  • C1, C2 = 6.63uF
  • L1, L2 = 0.42mH

Let’s also say you have some capacitors on hand that are below 6uF. By changing the crossover frequency slightly you can sometimes make use of parts you already have.

Example: changing the cutoff frequency to 3,500 would put the capacitor values needed close to 5.7uF. 

Obviously this won’t always work, and not all speakers are suited for it, but it’s a helpful strategy in some cases. Using a calculator, you can play around with values in seconds and see what works.

Your comments are welcome.
  1. I want to build a speaker box which has 16 speakers total which are 4 Subwoofers with 40 Hz to 3kHz, four Woofers are 50 Hz to 5kHz, 4 midranges 60 Hz to 7kHz, and four Tweeters 1kHz to 18kHz. I want them to go a combination of Series-Parallel from crossover
    Where string 1 are the Subs of A, B, C, D. and A and C get positive power and B and D get negative power, and negative of A is connected to positive of B, and negative of C is connected to positive D.
    String 2 is woofers, string 3 is midranges and string 4 is tweeters all wired series-parallel to crossover.
    Plus I want to add 3 more 1/4 jacks for daisy chaining more speakers which incoming power goes in the series-parallel of 1/4 jacks with speaker crossover leaving 3 outputs for daisy chaining. Currently using 500 watt amplifier at 8 ohm looking to upgrade that

    • Hello James it would be better to just contact me by email with a thorough drawing of what you’re trying to accomplish, the specs & driver impedances you have on hand, what you have or don’t have already, etc. It’s a bit too complex I think to help you here in a comment.

      Best regards.

  2. Dear Marty,
    i want to build 3-way speakers with passive crossovers.
    amp is 2 times 300watt 4ohm.
    Crossover is rated same watt.
    woofer and mid both 4ohm, tweeter i am not sure yet…
    My problem and i cant seem to find any clear info online.
    how do i know how much power will go to the mid and tweeter ?? i mean how to select them without having to worry about blowing them up.
    I saw a calculator on the side here where you can add powers ect, but all this changes when adding a crossover between ?? No ?

    • Hello Ronnie. For full-range crossovers like two or 3-way, the power to each speaker can be whatever the maximum is available from the amp. There’s very little, if any, power loss at the crossover.

      So you can treat it as if the crossover does not matter with regard to the power used.

      • Dear Marty,
        ok, so i get this now, but say you have following in a two-way passive speaker.
        Amp is 500 watt.
        woofer 500 watt
        tweeter 100 watt.
        So if the crossover is letting even power to both how can you protect this tweeter from this 500 watt ?
        i mean finding a woofer off 500 watt is easy, but i dont think a 500 watt tweeter even exist…
        So my big question is how to select a matching (watts) woofer and tweeter in a passive speaker (DIY project)
        I did find some info about matching the driver sensitivity to make the drivers about the same sensitivity output to let’s say linear the drivers…
        I really cannot find any info about this on the internet


        • Hi Ronnie. Well, for one thing that assumes the amplifier is actually 500W RMS or continuous per channel. Most aren’t, or perhaps the power ratings are confusing. However, let’s say it was the case:

          – The weakest speaker (the tweeter) will limit the power you can use.
          – You will either have to use tweeter protection components (tweeter protectors/fuses) or be sure to never exceed 100W power output. (Most likely the tweeter may hit its limit before 100W I’d bet.)

          You other option is the bi-amp the woofer and tweeters, meaning you can drive the woofers at a different power level than the tweeters safely by decreasing the level out from the tweeter channels.

          • Dear Marty,
            i actually want to build speakers like the JBL L100 classic, unfortunately i don’t find the jbl original parts for it.
            They are passive speakers with build in crossover, but i dont think the tweeter for example is rated as high power as the woofer…? i read online that crossovers can be build with this in mind to lower the output to mid and tweeter…correct ??
            So far my interest goes to Dayton Audio drivers, but again my big question is how to calculate all this ? do you know any calculator that calculate all of this things ?
            i find many smaller speakers kits from Dayton audio with parts and all clearly mentioned, but i am looking for the bigger, witch i don’ find…
            would be cool if someone tells me “use this and this ones”
            website i am looking for the parts is https://www.soundimports.eu/en/

            Many thx and regards,

          • Hello/hola Ronnie. Yes, you’re not going to find much information, if any, about this. That’s because it’s very unusual and not normally required for crossover design. If you want to do it, it will require some technical math (Ohms law, power/voltage/current type math).

            If you’re wanting to reduce the power to mids or tweeters there are two ways: 1. reduce the power output from an amp by bi-amping drivers, or 2. reduce the power to a driver by using one or more power resistors. The wasted power will be lost as heat. Power reduction is not normally done in a crossover, aside from a minimal amount of reduction to tweeters usually.

            You can also use multiple drivers as they’ll share the power load as they’ll receive less power each versus a single driver.

            The calculation(s) depends on how you’re wanting to accomplish this. When using series power resistors to a driver you can just use the old power formula P_driver = Pin x R_driver/(R_driver+R_resistor) where P = Power, R = Ohms. However if you want to maintain the same total Ohms load as the speaker it is a little more complicated.

            If you can to play around with power and resistance values, you can do this with my calculator here: https://soundcertified.com/speaker-ohms-calculator/
            …and use the “Series” or “Series-Parallel” options. My calculator can calculate the power division(s) and total Ohms load for various driver configurations.

            Que tengas un buen dia/have a good day.

  3. Hi, thanks for the explanation! I want to build a second order high pass filter for my car tweeters. Can I just take the L-R design and only use L1 and C1 and ignore the rest for the woofer and not use L2 and C2? Thanks again.

    • Hi Peter. I clearly remember responding to your comment/question some time back but oddly enough I don’t see it here. Sorry about that!

      Anyway, to answer your question: yes you can just leave off L2 & C2. That’s actually something I should make a note about so thanks for bringing it up. Best regards.

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