Today’s question is about those dreaded crossover points.
“Your audio reference CD is great. It helped me find a hot spot in my KRK monitors. It was 2.5khz -the crossover point. Is it normal for monitors to be hot (louder) at the crossover frequency?”
Frankly lots of bad stuff can happen at the crossover frequency in most systems, though the specific problems will vary from product to product. Ideally there would be no boost at any frequency and I’m sure a product of that quality is carefully designed to avoid such an irregularity. You didn’t say how much hotter it is. You may be observing the symptom of another problem. But there’s always going to be some degree of inconsistency at crossover points. Its severity is one of the factors separating the good monitors from the great ones.
Three key problems associated with crossover points are:
1) No matter how steep the filters there is still a frequency range that is being covered by two dissimilar drivers. This makes it very difficult to get linear frequency response and dispersion characteristics at those frequencies.
2) The filter circuitry that makes up a crossover produces phase shift. To a great extent this can be compensated for, but the result is never perfect.
3) There is a fundamental difference in the subjective “sound” of woofers as compared to tweeters and compression drivers. Never is this more apparent than when a sound must transition between the two. Vocals are often in this range, which serves to make the problem even more noticeable. There are a variety of design tricks employed to compensate for this, none perfect.
Between these problems (and other issues) there’s enough stuff going on at the crossover frequency that manufacturers pay a lot of attention to how things are sounding there. How a speaker responds to tones or pink noise is good for objective measurements, but how it responds to real world listening tests is often the final deciding factor that determines how things are tweaked to perform. Like much design work it becomes a series of compromises (one of which being cost) that must be weighed against each other. It’s possible the engineers at KRK decided to live with a slight boost at the crossover point in order to make the monitor “sound” better. It’s also likely that there is no boost from the speaker, but something is happening acoustically at your listening position to produce a peak.