This article explores some of the myths and facts about crossoverdesign. It also discusses some of the mistakes often made by loudspeakermanufacturers done either as cost savings or design incompetence. It is ourhope that the reader will gain a better understanding of the mechanics ofloudspeaker crossovers so they can make a more informed purchasingdecision.

The loudspeaker crossover can be considered thebrain of the loudspeaker. It directs thebandwidth of frequencies each driver is optimized to reproduce while it alsolevel matches each driver and can help to stabilize the load impedance theamplifier will see. Without theloudspeaker crossover, a loudspeaker driver such as a tweeter can be overdrivenwhich can lead to distortion and eventual failure. A loudspeaker system without a properlydesigned crossover (or none at all) can cause too much frequency overlapbetween drivers which can increase distortion and degrade overall soundquality.

For example graphically traced or downloaded manufacturer's response data is okay for preliminary studies, but not for final crossover design. Read Measurement with ARTA or REW or SoundEasy. This is mandatory document to read and follow to enable fast and controlled speaker simulation producing accurate off-axis simulation and reliable power.

LEAP Software - Analysis & Design of Loudspeakers, Enclosures, and Crossovers audiofox posts on July 18, 2013 13:58 I always wanted to splurge and get a copy of this software for my speaker building hobby-this is the SW that Madisound uses for their custom crossover and speaker design services. Unfortunately it seems there's a dearth of people who use Macs, design speakers, and program. We have probably the best measurement software out there (FuzzMeasure) but that's it. Too bad, because someone could capture the market with a decent crossover sim program. Mac users generally are willing to pay for apps, too.

Properly designing a loudspeaker crossover requiresengineering talent and sufficient budgeting to fit it into the total systemcost. There are often times manufacturerswill downplay the crossover’s importance, either because they lack theknowledge to truly understand its role, or they are simply attempting yetanother cost cutting tactic, assuming the buyer will never know since it’s outof sight, thus out of mind.

Let us briefly define some basic crossoverterminology which will help in the discussions later in this article. A High Pass Filter (HPF) bandwidth limitsfrequencies below where the driver is inefficient at (ormechanically incapable of) producing those frequencies. A Low Pass Filter (LPF) bandwidth limitsfrequencies above where the driver is inefficient at (ormechanically incapable of) producing those frequencies. Traditional filter theory deals with -3dB points where power is cut in half. However, since we are dealing with actual sound pressure (SPL) and not sound power, loudspeaker engineers typically deal with -6dB points when working with crossover networks.

Think of a tweeter trying to produce bassfrequencies. It can’t do so efficiently(or mechanically!) so we employ a HPF to block those frequencies. Conversely think of a woofer trying toproduce very high frequencies. We employa LPF to effectively filter the frequencies above which the woofer is capable ofproducing. The diagram pictured hereshows basic schematics of each filter type along with a generic theoreticalslope response. The squiggly lookingdevice is an inductor while the dual parallel adjacent lines represent acapacitor. This diagram is courtesy ofWilliamson-labs.com.

For more information on this topic, we recommendreading our article: Filter & Crossover Types for Loudspeakers

Myth #1: The SimplerCrossover is ALWAYS Better

We'veseen numerous loudspeaker companies defend their 2- or 3-element crossover (ie.Resistor/capacitor network only) as being preferred to a more complex crossovernetwork that their competitors employ on their designs. They argue that they custom designed theirdrivers to better integrate with each other, thus not needing a crossover withsteep slopes or an elaborate design to improve overall system impedance.

Tabulatedbelow is a list of filter slopes based on order for the readers reference:

First-order = 6 dB/Oct
Second-order = 12 dB/Oct
Third-order = 18 dB/Oct
Fourth-order = 24 dB/Oct

Thereality here is sometimes the exact opposite. A two- or three-element crossover on a two-way bookshelf speakertypically has no element at all on the midbass driver, allowing it to run fullrange. Unless the driver has beenmeticulously custom-designed and custom-manufactured to have a natural,precise, controlled rolloff at the upper end of its operating range (which istheoretically doable, but is often a very expensive proposition), the endresult would be break up distortion at higher frequencies which becomes audibleas the speaker is driven harder and why at least a second-order crossovernetwork is required to filter such distortion below audibility. This is especially true with stiff conedrivers that have a more prominent audible break up mode. Higher-order networks are typically neededin such cases. Having no network at allis NOT a viable solution if high fidelity reproduction is the primary goal ofthe speaker system.

First-orderfilters aren’t good at preventing distortion, particularly at or below thetweeter’s resonance frequency. They alsodon’t provide enough isolation of the bandwidths in multi driver systems. Theresult is too much of an opportunity for destructive interference, andtherefore a loss of uniformity across the crossover region with the wooferdoing most of the damage at high frequencies. It’s important to note that a tweeter still remains pistonic above andbelow Fc while a woofer does not. This is why second-order or higher filternetworks are typically employed but they are most costly to employ and complexto produce. The bigger parts are moreexpensive and more likely to cause insertion loss or burn out understress. This requires a tighter set oftolerances than a lower order network for the same amount of networkvariability.

Editorial Note About Directivity, Crossover Points & Driver Selection by Dr. Floyd Toole

A good sounding loudspeaker needs to have smoothand flat on-axis frequency response and similar performance as we movefar off axis. We describe this in terms of directivity as a function offrequency, and although absolutely constant directivity is notnecessary, smooth and gradually-changing directivity is a goodobjective. In deciding on the drivers to be used in a speaker system itis necessary to ensure that at crossover frequencies the drivers haveclosely matching directivities. This means that when the acoustictransition is made between, say, a woofer and a midrange, or a midrangeand a tweeter, there is continuity in the directional sound radiationpattern. It is not sufficientjust to have a good looking on-axis response. So, in addition toselecting drivers for their useable bandwidths and power handlingcapabilities, we need to pay attention to their directional radiationpatterns. The most difficult transitions occur when the transducersinvolved are very different in size.

EditorialNote by Steve Feinstein on Crossover Frequency Selection

A basic, ages-old but still true, rule ofthumb states that a designer is usually safe when he crosses a driver over atdouble its resonant frequency. If a tweeter has an Fs of 1500 Hz, use a 3000 Hzcrossover, minimum. If a midrange is 300 Hz, use 600 Hz.

Another good rule of thumb says, “18 dB downat resonance.” If a tweeter’s resonance is 1500 Hz, the voltage curve of thecrossover should show the tweeter section being down 18 dB from “0 dB.” Thatkind of conservatism all but assures no tweeter burn-out.

This was the “rule” at a major speakercompany I used to work at, and the engineers all hated it, because it was soconservative and resulted in very high tweeter crossover points. But we almostnever lost a tweeter and our warranty costs were vanishingly low. ‘Real world’vs. ‘theory.’

Aproperly designed filter network will always present a stable load impedance tothe amplifier. It will also properly bandwidth limit the loudspeaker drivers tolower their distortion and better integrate their response resulting in a moreeven on- and off-axis frequency response and power response. The power resp

Speaker Crossover Design Software Mac