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

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 both the high-pass and low-pass cutoff frequency. (*See my notes below regarding 3-way crossovers below.)

The wire calculator will output capacitor and inductor part values as needed.

Parts are labeled to match their place in the example schematic shown.

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 (milliHendrie) 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.

More helpful speaker crossover articles

Your comments are welcome!

  1. Question; if I have an 8 ohm tweeter and an 8 ohm woofer, how do I wire them together inside the cabinet? If I wire them in parallel they are 4 ohms which is fine for the amp but isn’t that changing the crossover frequency? What am I missing here? Thanks!

    Reply
    • Hi Lars. Actually, if you’re using a crossover, that should take care of it for you and the amp will only see 8 ohms, not 4.

      Typically there will be a 2-way crossover connected to the 8 ohm tweeter and woofer, either as a single 2-way crossover assembly or one or two components connected to each speaker inline.

      What happens is that for lower frequencies, the total Ohms load the amp sees is about 8 as only the woofer is driven (the tweeter crossover will block bass and have a very high impedance). Likewise, for high frequencies, the woofer’s crossover will have a very high impedance and the tweeter is the only speaker the amp will see.

      The end result is the amp is fine and the total Ohms load will be safe for your amp. NOTE: if you do not use a crossover, that’s very different. Just connecting two speakers in parallel without any type of crossover means that’s it’s simply the two speakers/Ohms in parallel.

      Hopefully that helps explain it a bit! :)

      Reply
  2. Yes that helps! I’m used to using full range speaker drivers so before when I tried two of those in one enclosure I would get 4 ohms which was fine. Now I’m trying 2 way speakers… I’ve heard about inexpensive speaker manufacturers using a simple capacitor to protect the tweeter and that was my plan. Can I not do that too?
    I thought 8 + 8 ohms in parallel = 4 ohms is ok but then what about the crossover frequency for the tweeter? Would I look for a capacitor targeting a 4 or 8 ohm impedance to get the correct frequency? Thanks so much!

    Reply
    • Hi Lars. Yes, speaker manufacturers sometimes use only a capacitor for the tweeter but often an inductor for the woofer as well. It depends on the design.

      You’ll pick the crossover components based on the impedance of the speaker. If they’re 8 ohms each, use that in each Ohms box in the speaker calculator. A speaker crossover works based on the speaker Ohms it’s connected to, not the total of the speakers.

      If you use a crossover (capacitor in this case) only for the tweeter, it will probably be fine, but it’s usually better to at least use a 2-way 1st order design for both speakers. Woofers usually sound pretty poor with highs sent to them.

      Reply

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