1. Xsim Crossover Machine
2. Is Crossover Safe For Mac

Generally speaking crossover design software combines loudspeaker SPL responses (that we have previously measured) with filter circuit data (also defined by us, the designers). This allows for the prediction (simulation) of overall speaker SPL responses which -in turn- verify whether design targets have been achieved or not.

The designer is expected to change filter component values in a repetitive manner and in a way that gets simulated responses closer to design targets. Obviously it is an exhaustive process.

In this video I get very technical and move quickly showing how to use this excellent software. Don't be discouraged if it's over your head. Take some time t. XSim is a freeware software solution that can come in handy if you’re struggling as a crossover designer, as it can lift a great deal of the burden by providing you with a complete environment to perform simulations, and schematics, without having to touch any of the actual equipment. Crossover simulation: Crossover topologies: Formal ladder, parallel or series: Free form: Response data: Single direction: Few directions: Quasi full space with responses in two planes.

Most crossover network software include an automatic optimization procedure which delivers the 'best' set of component values for a given set of design targets and circuit topology. In that sense no differences are expected to exist between different software implementations. However this optimization process may easily fail either if our design targets are impossible to fulfil or our circuit topology is too simple to realize them. In most cases we have to change our circuitry by adding extra components. This usually helps the optimization procedure find the proper components' 'solution'. Therefore successful crossover design often depends on human factor only. A detailed discussion of this issue is given in one of our tutorial articles on crossover design.

On the other hand we must be aware of the fact that crossover design is subject to one major flaw which is elaborated below:

Most woofers with low-to-medium sized diameters, exhibit a significant SPL step in the 100-500Hz frequency range due to baffle diffraction. Passive crossover filters can not 'adjust' the woofer's SPL response below 200-300 Hz. What they can do is to manipulate its mid-frequency range above 200-300Hz. A speaker to sound well must have a sort of balance between its 100Hz and 400Hz sound pressure levels. If the sound pressure dB level at 400Hz is 5 or 6 dB above the sound pressure level at 100Hz the speaker will sound 'empty'; music 'body' will be absent. So what crossover filters are expected to do is to suppress the sound pressure level above 400Hz so that it maintains a relatively small (or none at all) difference with respect to the 100Hz level.

For this task a designer must have an accurate woofer SPL response illustrating the baffle diffraction step in order to import it into the crossover design software. As we have already explained in the tutorials' section, reflections in our lab environment make SPL response measurement inaccurate below approximately 300Hz-400Hz. Typical measurement software removes SPL response values below this limit. As a consequence crossover design becomes 'blind' at very low frequencies and our speaker's sound balance gets compromised. Only sound engineers have access to large spaces (or anechoic chambers) for measuring purposes.

From a DIYer point of view crossover design software should be combined to a 'Baffle Diffraction Step' module. Capable of accepting enclosure data and woofer parameters, this module would simulate (predict) the missing low frequency SPL response up to 500-600Hz.

The crossoverdesign can make or break any multi-way loudspeaker. Having the world’s best drivers with a poorcrossover design will yield poor results. It is important to approach crossoverdesign with humility because it truly is an art that requires experience toperfect. Yes, it is possible to get decentsound by sending driver data sheets off for a generic crossover design. However, without proper analysis of thedrivers in the intended cabinet it is a game of roulette. This design overview neglects many designconsiderations a professional designer may consider such as time alignment,distortion and polar response but provides a starting point.

Before designing acrossover, the cabinet must be fully assembled including ports anddrivers. I typically run a separatespeaker wire from each driver out of the port and label each wire. For sealed loudspeakers, connect the wooferto the binding post as this is the first driver measured in the cabinet. Using SoundEasy, each driver is measured inthe cabinet to obtain frequency response and electrical impedance. These parameters are obtained following thetest methodology outlined in our LoudspeakerMeasurement Standard. Pleasenote that any measurements taken near field must factor in the effects ofbaffle diffraction. SoundEasy allowsmodeling and application of baffle diffraction estimates to any frequencyresponse data. Getting good measurementdata is one of the hardest parts of loudspeaker design. It is crucial to validate your results bytaking measurements using both near field and quasi-anechoic gated techniquesand compare the measurements before proceeding. The measurement data is subsequently used in SoundEasy’s crossoverdesign tool.

DIY Crossover Installed in Cabinet

Although CAD hascome a long way, designing a loudspeaker crossover benefits from somebackground in electronics. SoundEasy has2-way to 5-way crossover templates covering 1^st order to 4^thorder crossover topologies. Additionally, there are templates for a wide array of typical filtersand compensation circuits. The CADframework allows implementation of any circuit or filter topology imaginable solong as it uses inductors, resistors, capacitors, operational amplifiers,potentiometers or logic gates. If youhave not ever studied filter design or do not know what the previously-mentionedelements are, you may want to consider studying up to improve your chances ofpulling off a working and affordable solution.

The first step Itake when designing a crossover in SoundEasy is to determine workable crossoverfrequencies and filter orders. Thisrequires careful inspection of the driver data sheets, frequency responsemeasurement and driver impedance. It isimperative to make sure that response anomalies, such as the breakup of a metalcone driver, are sufficiently attenuated by the crossover so that they are notaudible. It is generally a good idea tokeep the crossover frequencies low enough to prevent driver beaming but highenough to prevent driver failure. Forexample, crossing over most tweeters below 1.5kHz is a bad idea if it is meantto play program material at 110dB or has a resonant frequency above 750Hz. Crossing an 8 inch bass driver at 5kHz willresult in poor dispersion and transient response at higher frequencies. As a rule of thumb, the max frequency for agiven driver diameter can be equated by taking 13560 and dividing it by thedrivers effective diameter. For an 8”driver with an effective cone diameter of 7”, this means that the maximumcrossover frequency should not exceed 1937Hz.

A 4^thorder crossover rolls off frequencies at 24dB per octave where as a 1^storder crossover rolls off frequencies at 6dB per octave. Lower order crossovers have less phase shiftbut tradeoff power handling and masking out of band response anomalies. The designer has to determine the best set oftradeoffs for an intended design goal. SoundEasy has built-in filter templates for delay networks if a designerdesires to design a time aligned loudspeaker for higher order filters. It is also important to note that the filterorder does not have to match for each driver in a system but it does simplifythe design.

Once approximatecrossover frequencies and filter orders are determined, a filter can be developedin CAD. For the purposes of this designanalysis, a 2^nd order crossover was designed which approximatelymatches a Butterworth filter target. Additional response shaping elements were added where needed to meet thedesign requirements. This circuit wasdetermined based on using a 2^nd order low-pass for the woofer,band-pass for the midrange and high-pass for the tweeter. Due to the response anomalies and differencesin sensitivity, additional elements were added. The final circuit design is shown below.

Crossover Circuit inCAD

The componentvalues for the circuit design are determined using SoundEasy’s ingeniousoptimization technique. It is as simpleas setting a target response for a single driver and selecting the componentsSoundEasy should manipulate to attempt to meet the target response. In this example, a 2^nd orderButterworth band-pass filter target was setup in the optimization dialog asshown in black in the figure below. SoundEasy will modify the selected crossover components and employ trialand error to arrive at the optimum component values required to meet thefrequency response target. Theoptimization technique will attempt thousands of combinations and may be runmultiple times to determine the best component values. While running optimization, it is important topay attention to the component values set by SoundEasy because it may setvalues that are very high inductances or capacitances and therefore expensive. This may take some playing around to getright. If you are unable to get close tothe target curve you might consider changing the filter topology. The midrange for the sample project tracksthe target curve pretty well but is not perfect at the high frequency knee dueto response problems with the driver itself. It is possible to shape the response further but more crossovercomponents equate to a more expensive crossover. It is easy to spend hundreds or eventhousands of dollars on crossover components. It is often better to solve extensive frequency response problems withbetter drivers or a more in-depth diffraction analysis.

Midrange CrossoverOptimization

The optimizationprocess is applied to the low-pass, band-pass and high-pass filters and acombined response is generated. Due toresponse issues, it may be necessary to attenuate a target or move thecrossover frequency slightly to obtain a flatter response. Ultimately, it may take several rounds ofmoving crossover frequencies and even filter orders to get to an acceptablesystem response. The combined systemresponse after optimization for this design is shown below.

3-Way CrossoverSummed Response

During the designprocess, it is important to pay close attention to system impedance graphs. It is no fun perfecting frequency when yourdesign has a minimum impedance of 1.5 Ohms. SoundEasy has an option to set the minimum acceptable impedance duringoptimization to help reduce the risk of developing a network that dips too lowfor the amplifier you are using.

As a final step,it is absolutely necessary to set the values of capacitors, resistors andinductors in the CAD editor to values you can actually purchase. This usually involves rounding up or down tovalues you can purchase. If thecrossover parts are expensive, you can attempt to reduce component values andsubsequently plot their effect on the final response. This is time consuming but can save you a tonof money. A 3-way crossover of thiscomplexity is not cheap. Using cheapelectrolytic capacitors this crossover costs close to $150 for componentsalone.

3-Way Crossover Billof Materials

Conclusion

Unfortunately, the tweeter used in this design did not measure close tothe data sheet at all and required pushing the crossover frequency up. Ultimately the dip at 4kHz is fixable but thecost required outweighs the benefit.

Personally, Iprefer loudspeakers that have a frequency response that tilts slightly downwardso I find the response of this speaker pleasing. It did not ultimately meet the design goal of+/-3dB frequency response deviation but it plays low bass with authority andsounds very good overall. Even though itis a ton of work, there is something very rewarding about designing aloudspeaker from the ground up and the owner of the speakers discussed in articleis extremely happy with his one of a kind creation.

DIY speaker Finished Product