Taking Your Own Measurements for Crossover Design

I have recently noticed a lot of DIYers designing crossovers using manufacturer-provided measurements. Designing a crossover with manufacturer data might seem like the easier, simpler route, but it will almost always lead to disappointing results.

Let’s explore why taking your own measurements enables much better outcomes in crossover design.

For this example, we’ll be designing a crossover for a simple 2-way prototype of a 3D-printed speaker I've been working on. The drivers we’re using are the Dayton RST28F-4 and RS125P-8.

Image 1. Measurement of the 3D-printed prototype featuring the RST28F-4 tweeter and RS125P-8 woofer.

Manufacturer's Measurements: The Easy but Flawed Option

Some manufacturers, like Dayton Audio, have frequency response and impedance data available for download on their website, which can be useful for driver comparisons, but it's not ideal for designing a high-quality crossover. These measurements are typically taken on large, flat, open baffles like the one pictured.

Image 2. Example of a manufacturer’s measurement setup, featuring a large flat baffle that doesn't reflect the design of any real speaker.

 

They don’t account for the unique design of your speaker. Critical factors like baffle step (how sound radiates around your baffle), edge diffraction (how high frequencies interact with speaker edges), and enclosure tuning are completely ignored. As a result, relying on this data for crossover design will result in misleading crossover simulations and poor results.

Here’s an example of a crossover I designed using only manufacturer-provided measurements.

Image 3. Screenshot of VituixCAD simulation of crossover using manufacturer measurements.

Note the seemingly flat response despite using very simple filters, it seems a bit too good to be true. There is also a distinct lack of directivity information, as Dayton only provides off-axis data up to ± 45 degrees, most manufacturers only provide on-axis data.

Taking Your Own Measurements

This is why taking your own measurements is essential. By using a cheap measurement microphone and software like Room EQ Wizard (REW), you can gather data specific to your speaker design. You'll be able to account for all the factors the manufacturer’s data ignores.

I start by measuring impedance using a DATS. Next, I measure each driver’s frequency response on and off-axis, both vertically and horizontally in 10-degree increments, 360 degrees, using the quasi-anechoic method described by Napilopez over at Audio Science Review (check out their guide here). This gives me a clear picture of the speaker's on-axis response, directivity, and other critical aspects.

Here is an example of a crossover I designed using my own measurements.

Image 4. Screenshot of VituixCAD simulation of crossover using my measurements.

Note that the crossover design and data in every window is very different despite being for the exact same speaker. I also have far more data to work with in the directivity window.

Why Does This Matter?

To understand why this matters, I assembled both crossovers, tested them on my prototype speaker, and took a gated, on-axis measurements.

Image 5. Gated measurement (200-20,000 Hz) comparison of both crossovers: my measurement-based crossover in blue, and the manufacturer’s measurement-based crossover in amber.

While both crossovers still need some work, the crossover designed using manufacturer measurements has a >6 dB dip in the bass caused by baffle step and a >4 dB dip in the upper midrange caused by edge diffraction. These are major issues that will result in a speaker that sounds thin and lacks midrange presence. These issues were completely invisible in the crossover simulation shown in image 3.

The crossover designed using my own measurements has no issues relating to baffle step and only some minor non-linearities in the midrange, which can be easily fixed with some minor component value tweaks.

The difference in response is purely down to the quality of data used in each crossover simulation. Both crossovers looked flat in the VituixCAD simulations; however, the final results of the crossover designed using manufacturer measurements are not even close to the simulation. The one designed using my measurements isn’t far off.

Why Don’t Manufacturers Provide More Accurate Data?

It’s not that they don’t want to—it’s just not feasible. Manufacturers can’t predict the unique design of your speaker cabinet or how you’ll use their drivers. That’s why they measure on standardised baffles, which provide useful comparisons between drivers but are not a substitute for real-world data.

Take Control of Your Crossover Design

If you’re serious about speaker design, relying solely on manufacturer measurements is not enough. Taking your own measurements gives you the data you need to design a crossover that accounts for the unique characteristics of your speaker, resulting in superior results.

So, next time you’re building a speaker, grab a measurement mic and start collecting your own data. It’s a bit more effort upfront, but the improvement in sound quality will be worth it.

Have you tried designing a crossover with your own measurements or with manufacturer measurements? Let me know how it went in the comments!