Bassonomy - our methodologies

Bassonomy is our structured approach to measurement and testing - the science and raw data behind every score. While we aim to keep things engaging and practical, our methods need to stay sustainable, and repeatable. This section bridges scientific rigor with clear, accessible explanations of our measurement process. More so - at the same time, our intuitive scores are designed to help you quickly evaluate and understand the results without deep dive to the technicalities.

Why do we test bass and midbass drivers:

Behind the seemingly simple design of a speaker driver lies a complex world of physics that can easily compromise performance. Turning all that into clear, useful insights is no small feat. Traditionally, the Thiele & Small parameter set tried to fill that gap - but it only describes driver behavior under small signals, where everything stays linear. That’s not how we use speakers - especially not subwoofers.

It became clear that large-signal measurements were needed to truly evaluate performance. Fortunately, teams of talented engineers stepped up. Systems like DUMAX, Klippel, and more recently Dayton Audio’s test gear, were developed to dig deeper—offering a peek under the hood of each driver. But even then, there's a disconnect: the raw data doesn’t always translate into practical, user-friendly terms.

That’s where Bassometry comes in - diving into the scientific deep end and resurfacing with insights and metrics that actually describe how a driver behaves and what it means for real-world use. At least, that’s the plan.

How do we test our reviewed the drivers.

Designing a meaningful, non-arbitrary testing process is always a challenge leaving certain gaps. But over time, it’s became clear that subwoofers and woofers rather behave more like electro-mechanical systems than purely acoustical ones. Yes, they produce sound - but often, that sound is more of a byproduct of pure mechanics than the core function of the driver itself.

Instead of just listening to the output (though we do that too), we focus on what’s happening inside the driver. As long as the cone and suspension aren’t physically falling apart - which we measure as well, analyzing electromechanical behavior reveals more than sound measurements, which are less stressful on the driver than our rigorous tests.

We can even assess significant aspects of total harmonic distortion (THD) mechanically, in ways that microphones often can’t capture.

What set of parameters did we choose to test?

Impedance shift and resonant frequency shift at driver´s Xmax: All dynamic speakers naturally show shifts in impedance and resonant frequency at their maximum excursion (Xmax). However, by observing how these parameters change, we can evaluate a driver’s mechanical stability and control over cone movement. These shifts are part of a broader balance of design choices, so a specific value isn’t always “right or wrong” within reasonable limits. But when those limits are exceeded, it indicates compromises that can affect the driver's usability and overall performance.
DC offset of the cone assembly during Xmax stimulus: When a speaker driver is pushed with a high-level signal, the cone’s center position can drift off from its neutral resting point. This offset can happen for several underlying reasons and usually signals trouble. Such drift introduces nonlinear distortion and effectively reduces usable excursion, as the driver hits its mechanical limits earlier than expected. It’s a clear warning sign—one that points to a loss of performance across the board.
Power draw at 15Hz, 40Hz/50Hz/70Hz at Xmax: This seemingly subtle test reveals key traits of a driver’s suspension, motor strength and efficiency. At 15Hz, we check how efficiently the driver converts power into motion—and how much of that power it absorbs. In high-end drivers, it’s possible for the suspension to consume nearly all input power, leaving little for actual sound output. That’s not ideal, but sometimes close to inevitable for best cone control. We also watch for weak motors that can’t drive the cone to its rated Xmax, leading to underperformance or even heat damage. At 50/70Hz, we test how well the cone assembly holds up under rapid, repeated full-stroke movement - something Xmax specs don’t tell you, but we do.
Mechanical THD: At 15Hz—where suspension behavior is often at its most nonlinear—and at 50Hz for subwoofers (75Hz for mid-woofers), we measure the distortion produced when the driver operates at its full rated linear excursion (Xmax). This reveals how cleanly the driver performs under stress, based purely on its mechanical behavior.
Output compression: Starting from -12dB below Xmax and pushing up to +3dB beyond (if the driver can handle it), we measure how much output is lost due to compression. This is assessed by comparing the actual cone displacement to what it should be, if no compression were occurring. It’s a key indicator of real-world performance limits.
Xmax class: Additional calculated marker from above, providing unidimensional information about real displacement capabilities of a driver. Either above or below specified Xmax, the unit evaluation will be expressed in levels from 0 to 4, from failing its Xmax range, to accepting +3dB punishment above Xmax gracefully.

For the best user experience, new test methods will always be considered - but only if their value to the community outweighs added complexity and resource demands. Practicality has its place in shaping our standard procedures.

For a full specification of our testing methods, please download the following methodology paper: